{
  "$schema_version": "5.3",
  "review_mode": "fresh",
  "claim_restatement": {
    "index_wording": "Xist Smart-Scaffold Hypothesis",
    "entry_form": "phenomenon",
    "gradeable_restatement": "Xist RNA directly binds and structurally tethers PRC1 and PRC2 across the inactive X chromosome, and this continuous Polycomb scaffold establishes X-linked silencing.",
    "restatement_required": true,
    "split_into": [],
    "parent_claim": null,
    "scope_qualifiers": [
      {
        "qualifier": "Species, cell lineage, developmental stage, native or ectopic expression and initiation versus maintenance",
        "determinable_before_outcome": true,
        "determined_from": "Enrollment and experimental design, before results; no responder-defined scope.",
        "action": "retained"
      }
    ]
  },
  "hypothesis": {
    "name": "Xist Smart-Scaffold Hypothesis",
    "central_claim": "Xist RNA directly binds and structurally tethers PRC1 and PRC2 across the inactive X chromosome, and this continuous Polycomb scaffold establishes X-linked silencing.",
    "proposed_mechanism": "Xist RNA directly binds and structurally tethers PRC1 and PRC2 across the inactive X chromosome, and this continuous Polycomb scaffold establishes X-linked silencing.",
    "claimed_scope": "Female mammalian XCI; species, differentiation stage, initiation versus maintenance, RNA abundance and gene classes are specified before outcomes.",
    "claimed_level": [
      "initiation",
      "maintenance"
    ],
    "is_conjunctive": true,
    "conjunctive_note": "The scaffold mechanism SC2 sets the nominal level, with SC3/SC4 necessity and continuous coating reported separately. Xist necessity and ectopic sufficiency SC1 cannot substitute for direct Polycomb tethering. Repeat modules, species, stage and cell lineage are fixed before outcomes."
  },
  "rubric_routing": {
    "primary_rubric": "03-epigenetics-gene-regulation.md",
    "secondary_rubrics": [],
    "index_notes_applied": [
      "The scaffold mechanism SC2 sets the nominal level, with SC3/SC4 necessity and continuous coating reported separately. Xist necessity and ectopic sufficiency SC1 cannot substitute for direct Polycomb tethering. Repeat modules, species, stage and cell lineage are fixed before outcomes."
    ],
    "rubric_fit_note": "Exact archived v5.3 framework. Any stale index empirical framing is rechecked against primary results."
  },
  "subclaim_matrix": {
    "subclaims": [
      {
        "id": "SC1",
        "statement": "Xist expression is necessary in cis and sufficient from an ectopic locus to establish chromosome-wide silencing.",
        "subclaim_type": "necessity",
        "scope": "mouse and human lineage, initiation and maintenance separately",
        "claimed_scope": "mouse and human lineage, initiation and maintenance separately",
        "governing_rubric": "03-epigenetics-gene-regulation.md",
        "key_evidence_anchor": "Allelic deletion and induction with chromosome-wide functional readout",
        "hsef_level": "Η",
        "confidence": "Moderate",
        "governing_cap_or_threshold": "Quoted boundary and upward audit below.",
        "rationale": "Native Xist deletions with dosage controls, induction sufficiency in defined competent cells and independently identified endogenous SPEN pathways converge on a causal initiating RNA. Human naive dampening and lineage-specific maintenance restrict scope; this is not universal silencing sufficiency in any cell."
      },
      {
        "id": "SC2",
        "statement": "Xist directly physically tethers PRC1 and PRC2 as a structural scaffold.",
        "subclaim_type": "mechanism",
        "scope": "native RNA abundance, PRC identity and stage",
        "claimed_scope": "native RNA abundance, PRC identity and stage",
        "governing_rubric": "03-epigenetics-gene-regulation.md",
        "key_evidence_anchor": "Direct interaction and separation-of-function endogenous perturbation",
        "hsef_level": "Γ",
        "confidence": "Moderate",
        "governing_cap_or_threshold": "Quoted boundary and upward audit below.",
        "rationale": "Direct PRC2 contact has biochemical and native UV-RIP support, but neither direct binding to both PRCs nor continuous structural tethering is isolated as the silencing mechanism. hnRNPK bridging, PRC1-first catalysis and dynamic release remain better supported. In-vitro contact cannot carry the registered conjunction above Γ."
      },
      {
        "id": "SC3",
        "statement": "Polycomb scaffolding is necessary to initiate X-linked transcriptional silencing.",
        "subclaim_type": "necessity",
        "scope": "initiation stage and gene set prespecified",
        "claimed_scope": "initiation stage and gene set prespecified",
        "governing_rubric": "03-epigenetics-gene-regulation.md",
        "key_evidence_anchor": "Polycomb-specific loss/rescue with nascent allele-specific output",
        "hsef_level": "Γ",
        "confidence": "Moderate",
        "governing_cap_or_threshold": "Quoted boundary and upward audit below.",
        "rationale": "Polycomb has causal, gene- and stage-dependent contributions, yet B/C deletion retains substantial initial silencing and matched SPEN/Polycomb loss supports parallel contributions. No positive experiment establishes necessity of a continuous direct scaffold for initiation."
      },
      {
        "id": "SC4",
        "statement": "Xist coats silenced Xi loci as a continuous physical scaffold.",
        "subclaim_type": "mechanism",
        "scope": "native Xi territory and molecule abundance",
        "claimed_scope": "native Xi territory and molecule abundance",
        "governing_rubric": "03-epigenetics-gene-regulation.md",
        "key_evidence_anchor": "Quantitative spatial/occupancy tests with finite-resolution controls",
        "hsef_level": "Β",
        "confidence": "Moderate",
        "governing_cap_or_threshold": "Quoted boundary and upward audit below.",
        "rationale": "Population coating and colocalization support broad association only. Sparse calibrated foci, protein amplification and accessible RNAPII argue against reifying a uniform continuous coat. This positive mechanistic subclaim stays at Β; that grade is not a denial of Xist localization."
      }
    ],
    "aggregation_rule": "primary-subclaim",
    "aggregation_preregistered": true,
    "aggregation_rationale": "The scaffold mechanism SC2 sets the nominal level, with SC3/SC4 necessity and continuous coating reported separately. Xist necessity and ectopic sufficiency SC1 cannot substitute for direct Polycomb tethering. Repeat modules, species, stage and cell lineage are fixed before outcomes.",
    "primary_subclaim_id": "SC2",
    "aggregation_derivation": "The preregistered primary-subclaim rule uses SC2, giving Γ for direct continuous Polycomb scaffolding. SC1 is Η within initiation-competent mammalian contexts, while SC3 is Γ and SC4 Β for their stronger mechanism claims. Weakest-link sensitivity is Β. Evidence for Xist necessity and modular Polycomb causality is retained and cannot replace the nominal structural claim.",
    "aggregation_alternatives": {
      "weakest_link_would_return": "Β",
      "primary_subclaim_would_return": "Γ",
      "scope_matched_would_return": "Γ",
      "note": "Separate narrow successes do not replace the preregistered gate."
    },
    "index_rule_deviation": ""
  },
  "competing_models": {
    "models_evaluated": [
      {
        "rank_in_tournament": 1,
        "model_id": "M2",
        "is_nominal": false,
        "name": "Modular effector pathways with a PRC1-first Polycomb cascade",
        "core_claim": "SPEN and Polycomb can contribute in parallel; hnRNPK bridges Xist to PCGF3/5, followed by catalytic chromatin recruitment.",
        "explains_what_nominal_does_not": "SPEN and Polycomb can contribute in parallel; hnRNPK bridges Xist to PCGF3/5, followed by catalytic chromatin recruitment.",
        "strongest_supporting_evidence": [
          "Recombinant KI-dependent bridging, native B/C perturbation and SPEN-SPOC/PCGF combined depletion resolve alternatives."
        ],
        "strongest_contradictory_evidence": [
          "Human domain independence and direct PRC2 UV contacts prevent a universal single-cascade claim."
        ],
        "hsef_level_for_this_model": "Ζ",
        "rationale": "Recombinant KI-dependent bridging, native B/C perturbation and SPEN-SPOC/PCGF combined depletion resolve alternatives. Human domain independence and direct PRC2 UV contacts prevent a universal single-cascade claim."
      },
      {
        "rank_in_tournament": 2,
        "model_id": "M5",
        "is_nominal": false,
        "name": "Xist-seeded protein assembly and spatial amplification",
        "core_claim": "Sparse RNA nucleates enriched effectors; compaction improves access to genes.",
        "explains_what_nominal_does_not": "Sparse RNA nucleates enriched effectors; compaction improves access to genes.",
        "strongest_supporting_evidence": [
          "Calibrated imaging, SPEN assembly perturbations and B-repeat effects support this defined mouse setting."
        ],
        "strongest_contradictory_evidence": [
          "Assembly is not proof of LLPS, and quantitative labeling plus lineage transfer remain limitations."
        ],
        "hsef_level_for_this_model": "Ε",
        "rationale": "Calibrated imaging, SPEN assembly perturbations and B-repeat effects support this defined mouse setting. Assembly is not proof of LLPS, and quantitative labeling plus lineage transfer remain limitations."
      },
      {
        "rank_in_tournament": 3,
        "model_id": "M3",
        "is_nominal": false,
        "name": "Dynamic RNA contact and catalytic release",
        "core_claim": "PRC2 contacts RNA transiently while folding/release regulates catalytic access.",
        "explains_what_nominal_does_not": "PRC2 contacts RNA transiently while folding/release regulates catalytic access.",
        "strongest_supporting_evidence": [
          "Native rG4 mutations preserve contact but deregulate marks and repression."
        ],
        "strongest_contradictory_evidence": [
          "Recruitment preservation and one main platform do not establish that this is the sole route."
        ],
        "hsef_level_for_this_model": "Ε",
        "rationale": "Native rG4 mutations preserve contact but deregulate marks and repression. Recruitment preservation and one main platform do not establish that this is the sole route."
      },
      {
        "rank_in_tournament": 4,
        "model_id": "M4",
        "is_nominal": false,
        "name": "Chromatin feedback and redundant maintenance",
        "core_claim": "Marks, architecture and RNA spreading reinforce one another with lineage-dependent memory.",
        "explains_what_nominal_does_not": "Marks, architecture and RNA spreading reinforce one another with lineage-dependent memory.",
        "strongest_supporting_evidence": [
          "Repeat B reciprocity, EED differentiation effects and somatic XIST deletion support defined feedback."
        ],
        "strongest_contradictory_evidence": [
          "Feedback alone does not explain initial SPEN-dependent repression or all human B-cell maintenance."
        ],
        "hsef_level_for_this_model": "Ε",
        "rationale": "Repeat B reciprocity, EED differentiation effects and somatic XIST deletion support defined feedback. Feedback alone does not explain initial SPEN-dependent repression or all human B-cell maintenance."
      },
      {
        "rank_in_tournament": 5,
        "model_id": "M1",
        "is_nominal": true,
        "name": "Direct continuous Polycomb smart scaffold",
        "core_claim": "Xist directly and continuously tethers both PRCs as the initiating silencing structure.",
        "explains_what_nominal_does_not": "Xist directly and continuously tethers both PRCs as the initiating silencing structure.",
        "strongest_supporting_evidence": [
          "RepA affinity, RNA association and direct PRC2 contact provide a plausible molecular foothold."
        ],
        "strongest_contradictory_evidence": [
          "Bridged recruitment, sparse RNA and retained initial repression without B/C-dependent marks oppose the full conjunction."
        ],
        "hsef_level_for_this_model": "Γ",
        "rationale": "RepA affinity, RNA association and direct PRC2 contact provide a plausible molecular foothold. Bridged recruitment, sparse RNA and retained initial repression without B/C-dependent marks oppose the full conjunction."
      }
    ],
    "tournament_summary": "Descriptive comparison; does not modify the nominal score. Pintacuda KI-domain tether controls identify adapter recruitment, while Bowness separation-of-function plus acute PCGF depletion distinguishes parallel effector causality from a generic RNA cloud. Markaki and Jachowicz add spatial amplification without establishing a continuous direct PRC tether.",
    "study_separating_rank1_from_rank2": "Pintacuda KI-domain tether controls identify adapter recruitment, while Bowness separation-of-function plus acute PCGF depletion distinguishes parallel effector causality from a generic RNA cloud. Markaki and Jachowicz add spatial amplification without establishing a continuous direct PRC tether.",
    "nominal_wins_only_by_funding_artifact": false,
    "level_unchanged_by_tournament": true
  },
  "evidence_inventory": [
    {
      "n": 1,
      "pmid": "38181737",
      "title": "XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells.",
      "citation": "Dror I, Chitiashvili T, Tan SYX et al. XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells. Cell. 2024.",
      "doi": "10.1016/j.cell.2023.11.033",
      "pmcid": "PMC10783549",
      "url": "https://pubmed.ncbi.nlm.nih.gov/38181737/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/38181737/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID38181737",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "human naive stem cells",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "XIST perturbation supports X-linked dampening and some autosomal targeting in naive cells.",
      "what_it_does_not_show": "Dampening and dispersed localization differ from complete cis silencing; no continuous Polycomb scaffold is isolated.",
      "confounders_present": [
        "Dampening and dispersed localization differ from complete cis silencing; no continuous Polycomb scaffold is isolated."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
        "supporting_count": 0,
        "mentioning_count": 0,
        "contrasting_count": 0,
        "notable_contrasting_statements": []
      },
      "shared_components": []
    },
    {
      "n": 2,
      "pmid": "25843628",
      "title": "Systematic discovery of Xist RNA binding proteins.",
      "citation": "Chu C, Zhang QC, da Rocha ST et al. Systematic discovery of Xist RNA binding proteins. Cell. 2015.",
      "doi": "10.1016/j.cell.2015.03.025",
      "pmcid": "PMC4425988",
      "url": "https://pubmed.ncbi.nlm.nih.gov/25843628/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/25843628/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID25843628",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse stem cells ChIRP-MS",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Interactome and knockdowns identify modular SPEN and hnRNPK functions coupled to differentiation.",
      "what_it_does_not_show": "Crosslinked association does not establish every interactor as a direct RNA binder or continuous tether.",
      "confounders_present": [
        "Crosslinked association does not establish every interactor as a direct RNA binder or continuous tether."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
        "supporting_count": 0,
        "mentioning_count": 0,
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        "notable_contrasting_statements": []
      },
      "shared_components": []
    },
    {
      "n": 3,
      "pmid": "25915022",
      "title": "The Xist lncRNA interacts directly with SHARP to silence transcription through HDAC3.",
      "citation": "McHugh CA, Chen CK, Chow A et al. The Xist lncRNA interacts directly with SHARP to silence transcription through HDAC3. Nature. 2015.",
      "doi": "10.1038/nature14443",
      "pmcid": "PMC4516396",
      "url": "https://pubmed.ncbi.nlm.nih.gov/25915022/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/25915022/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID25915022",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse stem cells RAP-MS",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Direct SHARP association and HDAC3/SMRT perturbation connect Xist to transcriptional repression and Pol II loss.",
      "what_it_does_not_show": "PRC2 recruitment dependence on this pathway does not itself prove direct Xist-PRC2 contact or a single serial cascade.",
      "confounders_present": [
        "PRC2 recruitment dependence on this pathway does not itself prove direct Xist-PRC2 contact or a single serial cascade."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
        "supporting_count": 0,
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      },
      "shared_components": []
    },
    {
      "n": 4,
      "pmid": "26177152",
      "title": "Cryptic RNA-binding by PRC2 components EZH2 and SUZ12.",
      "citation": "Betancur JG, Tomari Y. Cryptic RNA-binding by PRC2 components EZH2 and SUZ12. RNA biology. 2015.",
      "doi": "10.1080/15476286.2015.1069463",
      "pmcid": "PMC4615636",
      "url": "https://pubmed.ncbi.nlm.nih.gov/26177152/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/26177152/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID26177152",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "purified PRC2 subunits",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "EZH2 and SUZ12 bind RNA directly with length and substrate preferences.",
      "what_it_does_not_show": "Biochemical binding is not native selective tethering of both Polycomb complexes.",
      "confounders_present": [
        "Biochemical binding is not native selective tethering of both Polycomb complexes."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
        "supporting_count": 0,
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      },
      "shared_components": []
    },
    {
      "n": 5,
      "pmid": "32379046",
      "title": "Spen links RNA-mediated endogenous retrovirus silencing and X chromosome inactivation.",
      "citation": "Carter AC, Xu J, Nakamoto MY et al. Spen links RNA-mediated endogenous retrovirus silencing and X chromosome inactivation. eLife. 2020.",
      "doi": "10.7554/eLife.54508",
      "pmcid": "PMC7282817",
      "url": "https://pubmed.ncbi.nlm.nih.gov/32379046/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/32379046/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID32379046",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse stem cells chimeric RNA",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "An ERV element replaces A-repeat binding to SPEN and supports strictly local cis repression.",
      "what_it_does_not_show": "Local rescue cannot establish full chromosome silencing or Polycomb as the initiating scaffold.",
      "confounders_present": [
        "Local rescue cannot establish full chromosome silencing or Polycomb as the initiating scaffold."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
        "supporting_count": 0,
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      },
      "shared_components": []
    },
    {
      "n": 6,
      "pmid": "31175153",
      "title": "Kinetics of Xist-induced gene silencing can be predicted from combinations of epigenetic and genomic features.",
      "citation": "Barros de Andrade E Sousa L, Jonkers I, Syx L et al. Kinetics of Xist-induced gene silencing can be predicted from combinations of epigenetic and genomic features. Genome research. 2019.",
      "doi": "10.1101/gr.245027.118",
      "pmcid": "PMC6633258",
      "url": "https://pubmed.ncbi.nlm.nih.gov/31175153/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/31175153/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID31175153",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse allele-specific PRO-seq",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Repeat perturbations distinguish SPEN-dependent and pre-Polycomb-marked gene classes with different kinetics.",
      "what_it_does_not_show": "Predictive genomic features remain correlates; classes do not imply universal Polycomb necessity.",
      "confounders_present": [
        "Predictive genomic features remain correlates; classes do not imply universal Polycomb necessity."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
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        "supporting_count": 0,
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      },
      "shared_components": []
    },
    {
      "n": 7,
      "pmid": "12649488",
      "title": "Role of histone H3 lysine 27 methylation in X inactivation.",
      "citation": "Plath K, Fang J, Mlynarczyk-Evans SK et al. Role of histone H3 lysine 27 methylation in X inactivation. Science (New York, N.Y.). 2003.",
      "doi": "10.1126/science.1084274",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/12649488/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/12649488/",
      "tier": "A",
      "source_tier": "A",
      "kind": "primary",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID12649488",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse embryonic and extraembryonic cells",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Xist-dependent EED/EZH2 and H3K27 methylation can occur independently of Xist silencing function.",
      "what_it_does_not_show": "Recruitment and methylation are not sufficient for silencing; no continuous tether measured.",
      "confounders_present": [
        "Recruitment and methylation are not sufficient for silencing; no continuous tether measured."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
        "supporting_count": 0,
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      },
      "shared_components": []
    },
    {
      "n": 8,
      "pmid": "34813726",
      "title": "Xist nucleates local protein gradients to propagate silencing across the X chromosome.",
      "citation": "Markaki Y, Gan Chong J, Wang Y et al. Xist nucleates local protein gradients to propagate silencing across the X chromosome. Cell. 2021.",
      "doi": "10.1016/j.cell.2021.10.022",
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      "what_it_shows": "Calibrated sparse Xist foci nucleate many SPEN molecules; B-repeat loss impairs compaction and especially late silencing.",
      "what_it_does_not_show": "Molecule estimates depend on labeling calibration; local assemblies and protein gradients are not a continuous RNA coat.",
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      "title": "lncRNA-Induced Spread of Polycomb Controlled by Genome Architecture, RNA Abundance, and CpG Island DNA.",
      "citation": "Schertzer MD, Braceros KCA, Starmer J et al. lncRNA-Induced Spread of Polycomb Controlled by Genome Architecture, RNA Abundance, and CpG Island DNA. Molecular cell. 2019.",
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      "what_it_does_not_show": "Other lncRNAs and correlated domain patterns cannot alone identify the Xist recruitment mechanism.",
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        "Other lncRNAs and correlated domain patterns cannot alone identify the Xist recruitment mechanism."
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      "pmid": "11006266",
      "title": "XIST RNA associates with specific regions of the inactive X chromatin.",
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      "doi": "10.1074/jbc.C000409200",
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      "system": "human chromatin immunoprecipitation",
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      "what_it_shows": "XIST coprecipitates with macroH2A and hypoacetylated chromatin.",
      "what_it_does_not_show": "Chromatin association can be indirect and does not resolve a uniform RNA-Polycomb tether.",
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        "Chromatin association can be indirect and does not resolve a uniform RNA-Polycomb tether."
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      "title": "Deletion of the XIST promoter from the human inactive X chromosome compromises polycomb heterochromatin maintenance.",
      "citation": "Westervelt N, Yoest A, Sayed S et al. Deletion of the XIST promoter from the human inactive X chromosome compromises polycomb heterochromatin maintenance. Chromosoma. 2021.",
      "doi": "10.1007/s00412-021-00754-z",
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      "system": "diploid human somatic cells",
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      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "XIST promoter deletion reduces Polycomb marks without appreciable gene reactivation in the tested cells.",
      "what_it_does_not_show": "Maintenance redundancy is lineage-specific; it does not erase XIST initiation necessity.",
      "confounders_present": [
        "Maintenance redundancy is lineage-specific; it does not erase XIST initiation necessity."
      ],
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      "pmid": "28596365",
      "title": "PCGF3/5-PRC1 initiates Polycomb recruitment in X chromosome inactivation.",
      "citation": "Almeida M, Pintacuda G, Masui O et al. PCGF3/5-PRC1 initiates Polycomb recruitment in X chromosome inactivation. Science (New York, N.Y.). 2017.",
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      "what_it_shows": "PCGF3/5 double loss abolishes Xi Polycomb marks and compromises silencing; single-loss controls and embryos support a PRC1-first route.",
      "what_it_does_not_show": "Global PCGF loss and transgenic induction are not a direct RNA interface-specific test; phenotype does not prove PRC2-first scaffolding.",
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    {
      "n": 13,
      "pmid": "30595450",
      "title": "The Implication of Early Chromatin Changes in X Chromosome Inactivation.",
      "citation": "Żylicz JJ, Bousard A, Žumer K et al. The Implication of Early Chromatin Changes in X Chromosome Inactivation. Cell. 2019.",
      "doi": "10.1016/j.cell.2018.11.041",
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      "what_it_shows": "HDAC3 activity and early deacetylation accompany silencing before Polycomb spreads into genes.",
      "what_it_does_not_show": "Temporal order and HDAC3 perturbation do not require that all Polycomb activity lies downstream of SPEN.",
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      "pmid": "32025035",
      "title": "SPEN integrates transcriptional and epigenetic control of X-inactivation.",
      "citation": "Dossin F, Pinheiro I, Żylicz JJ et al. SPEN integrates transcriptional and epigenetic control of X-inactivation. Nature. 2020.",
      "doi": "10.1038/s41586-020-1974-9",
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      "pmid": "16415857",
      "title": "The Polycomb group protein Eed protects the inactive X-chromosome from differentiation-induced reactivation.",
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      "what_it_does_not_show": "A differentiation-dependent memory role is not general Polycomb dispensability at initiation.",
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      "title": "SPEN is required for Xist upregulation during initiation of X chromosome inactivation.",
      "citation": "Robert-Finestra T, Tan BF, Mira-Bontenbal H et al. SPEN is required for Xist upregulation during initiation of X chromosome inactivation. Nature communications. 2021.",
      "doi": "10.1038/s41467-021-27294-5",
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    {
      "n": 17,
      "pmid": "39256583",
      "title": "Stepwise de novo establishment of inactive X chromosome architecture in early development.",
      "citation": "Du Z, Hu L, Zou Z et al. Stepwise de novo establishment of inactive X chromosome architecture in early development. Nature genetics. 2024.",
      "doi": "10.1038/s41588-024-01897-2",
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      "what_it_shows": "Xist regulatory-region disruption and cohesin degradation link stage-specific megadomains to local regulation.",
      "what_it_does_not_show": "Chromosome folding boundaries are not direct Polycomb tethers and may be strain-specific.",
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      "pmid": "30783652",
      "title": "En bloc and segmental deletions of human XIST reveal X chromosome inactivation-involving RNA elements.",
      "citation": "Lee HJ, Gopalappa R, Sunwoo H et al. En bloc and segmental deletions of human XIST reveal X chromosome inactivation-involving RNA elements. Nucleic acids research. 2019.",
      "doi": "10.1093/nar/gkz109",
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        "A cancer cell line and maintenance context cannot fix all human developmental domains or the direct PRC binding interface."
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      "title": "RNA polymerase II depletion from the inactive X chromosome territory is not mediated by physical compartmentalization.",
      "citation": "Collombet S, Rall I, Dugast-Darzacq C et al. RNA polymerase II depletion from the inactive X chromosome territory is not mediated by physical compartmentalization. Nature structural & molecular biology. 2023.",
      "doi": "10.1038/s41594-023-01008-5",
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      "what_it_does_not_show": "Accessible diffusion does not exclude all local protein assemblies or every mature Xi physical effect.",
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      "pmid": "21613321",
      "title": "Incomplete X-inactivation initiated by a hypomorphic Xist allele in the mouse.",
      "citation": "Hoki Y, Ikeda R, Mise N et al. Incomplete X-inactivation initiated by a hypomorphic Xist allele in the mouse. Development (Cambridge, England). 2011.",
      "doi": "10.1242/dev.061226",
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      "study_id": "PMID21613321",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse hypomorphic Xist allele",
      "decisive_perturbation": true,
      "endogenous": true,
      "direction": "contradicting",
      "what_it_shows": "Mutant Xist coats the X yet establishes incomplete and unstable silencing.",
      "what_it_does_not_show": "Coating is insufficient; the allele perturbs more than a selective Polycomb interface.",
      "confounders_present": [
        "Coating is insufficient; the allele perturbs more than a selective Polycomb interface."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 21,
      "pmid": "30428357",
      "title": "Smchd1 Targeting to the Inactive X Is Dependent on the Xist-HnrnpK-PRC1 Pathway.",
      "citation": "Jansz N, Nesterova T, Keniry A et al. Smchd1 Targeting to the Inactive X Is Dependent on the Xist-HnrnpK-PRC1 Pathway. Cell reports. 2018.",
      "doi": "10.1016/j.celrep.2018.10.044",
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      "url": "https://pubmed.ncbi.nlm.nih.gov/30428357/",
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      "opened_on": "2026-10-09",
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      "study_id": "PMID30428357",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse Smchd1 recruitment perturbations",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "SMCHD1 recruitment depends on the Xist-hnRNPK-PRC1/H2AK119ub pathway and lacks specific RNA binding in assays.",
      "what_it_does_not_show": "This supports indirect downstream recruitment rather than proving PRC2 never contacts Xist.",
      "confounders_present": [
        "This supports indirect downstream recruitment rather than proving PRC2 never contacts Xist."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 22,
      "pmid": "1423610",
      "title": "The product of the mouse Xist gene is a 15 kb inactive X-specific transcript containing no conserved ORF and located in the nucleus.",
      "citation": "Brockdorff N, Ashworth A, Kay GF et al. The product of the mouse Xist gene is a 15 kb inactive X-specific transcript containing no conserved ORF and located in the nucleus. Cell. 1992.",
      "doi": "10.1016/0092-8674(92)90519-i",
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID1423610",
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      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Weak",
      "system": "mouse and human transcript characterization",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Xist is a conserved nuclear untranslated repeat-containing transcript expressed from Xi.",
      "what_it_does_not_show": "Localization and sequence conservation are discovery evidence, not silencing causality or scaffold necessity.",
      "confounders_present": [
        "Localization and sequence conservation are discovery evidence, not silencing causality or scaffold necessity."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 23,
      "pmid": "23828888",
      "title": "The Xist lncRNA exploits three-dimensional genome architecture to spread across the X chromosome.",
      "citation": "Engreitz JM, Pandya-Jones A, McDonel P et al. The Xist lncRNA exploits three-dimensional genome architecture to spread across the X chromosome. Science (New York, N.Y.). 2013.",
      "doi": "10.1126/science.1237973",
      "pmcid": "PMC3778663",
      "url": "https://pubmed.ncbi.nlm.nih.gov/23828888/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/23828888/",
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      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID23828888",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse RNA antisense purification and induction",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Xist spreading exploits pre-existing 3D proximity and its silencing domain to access active regions.",
      "what_it_does_not_show": "Population occupancy maps do not show simultaneous uniform coverage in individual cells.",
      "confounders_present": [
        "Population occupancy maps do not show simultaneous uniform coverage in individual cells."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 24,
      "pmid": "26739568",
      "title": "Sex-specific silencing of X-linked genes by Xist RNA.",
      "citation": "Gayen S, Maclary E, Hinten M et al. Sex-specific silencing of X-linked genes by Xist RNA. Proceedings of the National Academy of Sciences of the United States of America. 2016.",
      "doi": "10.1073/pnas.1515971113",
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      "url": "https://pubmed.ncbi.nlm.nih.gov/26739568/",
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      "opened_on": "2026-10-09",
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      "study_id": "PMID26739568",
      "access_depth": "abstract_metadata",
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      "relates_to_subclaims": [
        "SC1",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse Tsix ablation embryos and stem cells",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Comparable Xist induction/coating yields sex- and X-dose-dependent differences in silencing.",
      "what_it_does_not_show": "Coating alone is insufficient; ectopic Tsix-driven expression does not represent every normal initiation condition.",
      "confounders_present": [
        "Coating alone is insufficient; ectopic Tsix-driven expression does not represent every normal initiation condition."
      ],
      "verification": "verified",
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    {
      "n": 25,
      "pmid": "20657585",
      "title": "The A-repeat links ASF/SF2-dependent Xist RNA processing with random choice during X inactivation.",
      "citation": "Royce-Tolland ME, Andersen AA, Koyfman HR et al. The A-repeat links ASF/SF2-dependent Xist RNA processing with random choice during X inactivation. Nature structural & molecular biology. 2010.",
      "doi": "10.1038/nsmb.1877",
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      "relates_to_subclaims": [
        "SC1",
        "SC3"
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      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse A-repeat processing mutants",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "A-repeat regulates spliced Xist accumulation and random choice.",
      "what_it_does_not_show": "A-repeat deletion has an RNA-processing confound and cannot be read solely as selective PRC2 binding loss.",
      "confounders_present": [
        "A-repeat deletion has an RNA-processing confound and cannot be read solely as selective PRC2 binding loss."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 26,
      "pmid": "33605056",
      "title": "H4K20me1 and H3K27me3 are concurrently loaded onto the inactive X chromosome but dispensable for inducing gene silencing.",
      "citation": "Tjalsma SJD, Hori M, Sato Y et al. H4K20me1 and H3K27me3 are concurrently loaded onto the inactive X chromosome but dispensable for inducing gene silencing. EMBO reports. 2021.",
      "doi": "10.15252/embr.202051989",
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      "url": "https://pubmed.ncbi.nlm.nih.gov/33605056/",
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID33605056",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC3",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse live mark imaging and Xist mutants",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "B/C-deficient Xist retains silencing despite loss of H3K27me3 and H4K20me1 accumulation.",
      "what_it_does_not_show": "Retained initiation does not exclude stabilization or gene-specific Polycomb dependence.",
      "confounders_present": [
        "Retained initiation does not exclude stabilization or gene-specific Polycomb dependence."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 27,
      "pmid": "29220657",
      "title": "hnRNPK Recruits PCGF3/5-PRC1 to the Xist RNA B-Repeat to Establish Polycomb-Mediated Chromosomal Silencing.",
      "citation": "Pintacuda G, Wei G, Roustan C et al. hnRNPK Recruits PCGF3/5-PRC1 to the Xist RNA B-Repeat to Establish Polycomb-Mediated Chromosomal Silencing. Molecular cell. 2017.",
      "doi": "10.1016/j.molcel.2017.11.013",
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      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "Oxford-PCGF-Xist-platform",
      "access_depth": "full_text_partial",
      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph44, 1:Results:paragraph49, 1:Results:paragraph50, 1:Results:paragraph51, 1:Results:paragraph60, 1:Results:paragraph61, 1:Results:paragraph62. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [
        "M2"
      ],
      "evidence_class": "Strong",
      "system": "mouse RNA domains recombinant proteins and tether rescue",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "hnRNPK directly bridges B-repeat to PCGF3-PRC1; KI-deficient and GFP tether controls fail while hnRNPK restores marks and silencing.",
      "what_it_does_not_show": "Synthetic tethering is a mechanistic rescue within engineered cells, not proof of a direct continuous RNA interaction with both PRCs.",
      "confounders_present": [
        "Synthetic tethering is a mechanistic rescue within engineered cells, not proof of a direct continuous RNA interaction with both PRCs."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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        "note": "Provider-indexed aggregate citation counts and selected outgoing references, not an incoming contradiction-body audit or quality score."
      },
      "shared_components": [
        "Related Oxford inducible transgenes and PCGF pathway work; rescue and recombinant biochemistry exclude different errors."
      ]
    },
    {
      "n": 28,
      "pmid": "33268787",
      "title": "Structural modularity of the XIST ribonucleoprotein complex.",
      "citation": "Lu Z, Guo JK, Wei Y et al. Structural modularity of the XIST ribonucleoprotein complex. Nature communications. 2020.",
      "doi": "10.1038/s41467-020-20040-3",
      "pmcid": "PMC7710737",
      "url": "https://pubmed.ncbi.nlm.nih.gov/33268787/",
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      "tier": "A",
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      "opened_on": "2026-10-09",
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      "study_id": "PMID33268787",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "human and mouse RNA structure interaction mapping",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Orthogonal RNA structure and interaction methods plus A-repeat relocation show modular RNP architecture.",
      "what_it_does_not_show": "A structured modular RNA is not automatically a chromosome-wide Polycomb scaffold.",
      "confounders_present": [
        "A structured modular RNA is not automatically a chromosome-wide Polycomb scaffold."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 29,
      "pmid": "31456285",
      "title": "The role of Xist-mediated Polycomb recruitment in the initiation of X-chromosome inactivation.",
      "citation": "Bousard A, Raposo AC, Żylicz JJ et al. The role of Xist-mediated Polycomb recruitment in the initiation of X-chromosome inactivation. EMBO reports. 2019.",
      "doi": "10.15252/embr.201948019",
      "pmcid": "PMC6776897",
      "url": "https://pubmed.ncbi.nlm.nih.gov/31456285/",
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      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph0, 1:Results:paragraph15, 1:Results:paragraph26, 1:Results:paragraph28, 1:Results:paragraph42, 1:Results:paragraph52, 1:Results:paragraph63. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "endogenous mouse Xist inducible B/C deletions",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "B/C loss removes PCGF3/5 association and global marks while most initial silencing persists; RNA stability/coating and A-repeat controls distinguish effects.",
      "what_it_does_not_show": "Induced XY expression exceeds native maintenance signal and residual promoter marks remain; modest silencing deficits cannot be described as zero Polycomb function.",
      "confounders_present": [
        "Induced XY expression exceeds native maintenance signal and residual promoter marks remain; modest silencing deficits cannot be described as zero Polycomb function."
      ],
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    {
      "n": 30,
      "pmid": "28546514",
      "title": "The nuclear matrix protein CIZ1 facilitates localization of Xist RNA to the inactive X-chromosome territory.",
      "citation": "Ridings-Figueroa R, Stewart ER, Nesterova TB et al. The nuclear matrix protein CIZ1 facilitates localization of Xist RNA to the inactive X-chromosome territory. Genes & development. 2017.",
      "doi": "10.1101/gad.295907.117",
      "pmcid": "PMC5458755",
      "url": "https://pubmed.ncbi.nlm.nih.gov/28546514/",
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      "study_id": "PMID28546514",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse Ciz1 knockout and human localization",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "CIZ1 loss disperses Xist in somatic lineages and re-expression restores focal localization.",
      "what_it_does_not_show": "Anchoring to a matrix is not direct binding of Xist to both PRCs; viable mutants restrict universality.",
      "confounders_present": [
        "Anchoring to a matrix is not direct binding of Xist to both PRCs; viable mutants restrict universality."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 31,
      "pmid": "33725485",
      "title": "Balancing cohesin eviction and retention prevents aberrant chromosomal interactions, Polycomb-mediated repression, and X-inactivation.",
      "citation": "Kriz AJ, Colognori D, Sunwoo H et al. Balancing cohesin eviction and retention prevents aberrant chromosomal interactions, Polycomb-mediated repression, and X-inactivation. Molecular cell. 2021.",
      "doi": "10.1016/j.molcel.2021.02.031",
      "pmcid": "PMC8106664",
      "url": "https://pubmed.ncbi.nlm.nih.gov/33725485/",
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      "tier": "A",
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        "none_found"
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      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID33725485",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC3",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse endogenous RAD21/WAPL degrons",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Cohesin loss greatly changes Xi structure with little repression change, whereas retention disrupts Xist spreading and silencing.",
      "what_it_does_not_show": "Structure-function dependence is asymmetric and cannot be reduced to all structural perturbations causing transcription loss.",
      "confounders_present": [
        "Structure-function dependence is asymmetric and cannot be reduced to all structural perturbations causing transcription loss."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 32,
      "pmid": "28923964",
      "title": "Repeat E anchors Xist RNA to the inactive X chromosomal compartment through CDKN1A-interacting protein (CIZ1).",
      "citation": "Sunwoo H, Colognori D, Froberg JE et al. Repeat E anchors Xist RNA to the inactive X chromosomal compartment through CDKN1A-interacting protein (CIZ1). Proceedings of the National Academy of Sciences of the United States of America. 2017.",
      "doi": "10.1073/pnas.1711206114",
      "pmcid": "PMC5635913",
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      "relates_to_subclaims": [
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      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse Repeat E and CIZ1 genetics",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Repeat E/CIZ1 loss and CIZ1 overexpression disperse Xist with reduced H3K27me3.",
      "what_it_does_not_show": "Dose-sensitive local anchoring does not establish continuous chromosome-wide RNA occupancy.",
      "confounders_present": [
        "Dose-sensitive local anchoring does not establish continuous chromosome-wide RNA occupancy."
      ],
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    {
      "n": 33,
      "pmid": "26089354",
      "title": "Chromosomes. A comprehensive Xist interactome reveals cohesin repulsion and an RNA-directed chromosome conformation.",
      "citation": "Minajigi A, Froberg J, Wei C et al. Chromosomes. A comprehensive Xist interactome reveals cohesin repulsion and an RNA-directed chromosome conformation. Science (New York, N.Y.). 2015.",
      "doi": "10.1126/science.aab2276",
      "pmcid": "PMC4845908",
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        "SC2",
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        "SC4"
      ],
      "favors_models": [],
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      "system": "mouse iDRiP and combinatorial inhibition",
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      "direction": "supporting",
      "what_it_shows": "Broad Xist interactome and multi-factor inhibition reveal layered repression and cohesin eviction.",
      "what_it_does_not_show": "Association/proteomic sensitivity and multi-target intervention do not identify a unique direct PRC scaffold.",
      "confounders_present": [
        "Association/proteomic sensitivity and multi-target intervention do not identify a unique direct PRC scaffold."
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    {
      "n": 34,
      "pmid": "29887375",
      "title": "SMCHD1 Merges Chromosome Compartments and Assists Formation of Super-Structures on the Inactive X.",
      "citation": "Wang CY, Jégu T, Chu HP et al. SMCHD1 Merges Chromosome Compartments and Assists Formation of Super-Structures on the Inactive X. Cell. 2018.",
      "doi": "10.1016/j.cell.2018.05.007",
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      "relates_to_subclaims": [
        "SC3",
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      "evidence_class": "Strong",
      "system": "mouse SMCHD1 ablation and conformation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "SMCHD1 loss preserves intermediate compartments, impairs regional Xist spread and silencing.",
      "what_it_does_not_show": "Architectural contribution is downstream or cooperative, not continuous direct Xist-PRC tethering.",
      "confounders_present": [
        "Architectural contribution is downstream or cooperative, not continuous direct Xist-PRC tethering."
      ],
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      "n": 35,
      "pmid": "26190105",
      "title": "A Pooled shRNA Screen Identifies Rbm15, Spen, and Wtap as Factors Required for Xist RNA-Mediated Silencing.",
      "citation": "Moindrot B, Cerase A, Coker H et al. A Pooled shRNA Screen Identifies Rbm15, Spen, and Wtap as Factors Required for Xist RNA-Mediated Silencing. Cell reports. 2015.",
      "doi": "10.1016/j.celrep.2015.06.053",
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      "access_depth": "abstract_metadata",
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      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse pooled shRNA screen and validation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "SPEN RBM15 and WTAP perturbations impair establishment and factors colocalize with Xist.",
      "what_it_does_not_show": "shRNA and colocalization can involve RNA abundance or indirect effects; later acute m6A tests revise necessity.",
      "confounders_present": [
        "shRNA and colocalization can involve RNA abundance or indirect effects; later acute m6A tests revise necessity."
      ],
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    {
      "n": 36,
      "pmid": "32813011",
      "title": "hnRNPK recognition of the B motif of Xist and other biological RNAs.",
      "citation": "Nakamoto MY, Lammer NC, Batey RT et al. hnRNPK recognition of the B motif of Xist and other biological RNAs. Nucleic acids research. 2020.",
      "doi": "10.1093/nar/gkaa677",
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      "status_checked_on": "2026-10-09",
      "study_id": "PMID32813011",
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      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "hnRNPK biochemistry and in-cell crosslink comparison",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Multiple hnRNPK domains and RNA conformation determine B-motif binding affinity.",
      "what_it_does_not_show": "C-patch preference is not sufficient to predict every cellular binding site; isolated affinity does not establish continuous occupancy.",
      "confounders_present": [
        "C-patch preference is not sufficient to predict every cellular binding site; isolated affinity does not establish continuous occupancy."
      ],
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    {
      "n": 37,
      "pmid": "27602518",
      "title": "m(6)A RNA methylation promotes XIST-mediated transcriptional repression.",
      "citation": "Patil DP, Chen CK, Pickering BF et al. m(6)A RNA methylation promotes XIST-mediated transcriptional repression. Nature. 2016.",
      "doi": "10.1038/nature19342",
      "pmcid": "PMC5509218",
      "url": "https://pubmed.ncbi.nlm.nih.gov/27602518/",
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      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "human methylation knockdown and YTHDC1 tethering",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "m6A machinery knockdown impairs XIST repression and synthetic YTHDC1 tethering rescues it.",
      "what_it_does_not_show": "Transcript-wide effects and engineered rescue do not establish native m6A necessity; acute METTL3 depletion produces a different result.",
      "confounders_present": [
        "Transcript-wide effects and engineered rescue do not establish native m6A necessity; acute METTL3 depletion produces a different result."
      ],
      "verification": "verified",
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    {
      "n": 38,
      "pmid": "33735607",
      "title": "B cell-specific XIST complex enforces X-inactivation and restrains atypical B cells.",
      "citation": "Yu B, Qi Y, Li R et al. B cell-specific XIST complex enforces X-inactivation and restrains atypical B cells. Cell. 2021.",
      "doi": "10.1016/j.cell.2021.02.015",
      "pmcid": "PMC9196326",
      "url": "https://pubmed.ncbi.nlm.nih.gov/33735607/",
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      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC3"
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      "favors_models": [],
      "evidence_class": "Strong",
      "system": "adult human B-cell proteomics CRISPRi and perturbation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "XIST continuously restrains a subset of immune genes through lineage-specific repression with TRIM28.",
      "what_it_does_not_show": "B-cell maintenance differs from diploid somatic redundancy; continual XIST requirement is not a continuous Polycomb scaffold.",
      "confounders_present": [
        "B-cell maintenance differs from diploid somatic redundancy; continual XIST requirement is not a continuous Polycomb scaffold."
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    {
      "n": 39,
      "pmid": "9009199",
      "title": "Xist-deficient mice are defective in dosage compensation but not spermatogenesis.",
      "citation": "Marahrens Y, Panning B, Dausman J et al. Xist-deficient mice are defective in dosage compensation but not spermatogenesis. Genes & development. 1997.",
      "doi": "10.1101/gad.11.2.156",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/9009199/",
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      "study_id": "PMID9009199",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse Xist structural deletion",
      "decisive_perturbation": true,
      "endogenous": true,
      "direction": "supporting",
      "what_it_shows": "Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects.",
      "what_it_does_not_show": "These controls establish Xist function without distinguishing direct PRC tethering from modular recruitment.",
      "confounders_present": [
        "These controls establish Xist function without distinguishing direct PRC tethering from modular recruitment."
      ],
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    {
      "n": 40,
      "pmid": "8425217",
      "title": "Expression of Xist during mouse development suggests a role in the initiation of X chromosome inactivation.",
      "citation": "Kay GF, Penny GD, Patel D et al. Expression of Xist during mouse development suggests a role in the initiation of X chromosome inactivation. Cell. 1993.",
      "doi": "10.1016/0092-8674(93)90658-d",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/8425217/",
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      "study_id": "PMID8425217",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1"
      ],
      "favors_models": [],
      "evidence_class": "Weak",
      "system": "mouse developmental expression",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Xist expression precedes XCI and shows developmental imprinting.",
      "what_it_does_not_show": "Temporal precedence without perturbation cannot establish necessary scaffold action.",
      "confounders_present": [
        "Temporal precedence without perturbation cannot establish necessary scaffold action."
      ],
      "verification": "verified",
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    {
      "n": 41,
      "pmid": "2034279",
      "title": "Conservation of position and exclusive expression of mouse Xist from the inactive X chromosome.",
      "citation": "Brockdorff N, Ashworth A, Kay GF et al. Conservation of position and exclusive expression of mouse Xist from the inactive X chromosome. Nature. 1991.",
      "doi": "10.1038/351329a0",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/2034279/",
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      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1"
      ],
      "favors_models": [],
      "evidence_class": "Weak",
      "system": "mouse interspecific hybrid mapping",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Conserved locus and exclusive Xi expression identify a candidate dosage-compensation RNA.",
      "what_it_does_not_show": "Mapping and association alone do not show causality.",
      "confounders_present": [
        "Mapping and association alone do not show causality."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 42,
      "pmid": "10882105",
      "title": "A shift from reversible to irreversible X inactivation is triggered during ES cell differentiation.",
      "citation": "Wutz A, Jaenisch R. A shift from reversible to irreversible X inactivation is triggered during ES cell differentiation. Molecular cell. 2000.",
      "doi": "10.1016/s1097-2765(00)80248-8",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/10882105/",
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      "study_id": "PMID10882105",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse inducible Xist transgene",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent.",
      "what_it_does_not_show": "Ectopic sufficiency is context-limited; irreversible maintenance does not require continuous RNA scaffold persistence.",
      "confounders_present": [
        "Ectopic sufficiency is context-limited; irreversible maintenance does not require continuous RNA scaffold persistence."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 43,
      "pmid": "11780141",
      "title": "Chromosomal silencing and localization are mediated by different domains of Xist RNA.",
      "citation": "Wutz A, Rasmussen TP, Jaenisch R. Chromosomal silencing and localization are mediated by different domains of Xist RNA. Nature genetics. 2002.",
      "doi": "10.1038/ng820",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/11780141/",
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      "study_id": "PMID11780141",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC3",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse inducible RNA-domain deletions",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "A-repeat loss preserves localization/spreading but abolishes silencing, separating functions.",
      "what_it_does_not_show": "Engineered cDNA-domain behavior cannot alone identify native PRC recruitment interfaces.",
      "confounders_present": [
        "Engineered cDNA-domain behavior cannot alone identify native PRC recruitment interfaces."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 44,
      "pmid": "8538762",
      "title": "Requirement for Xist in X chromosome inactivation.",
      "citation": "Penny GD, Kay GF, Sheardown SA et al. Requirement for Xist in X chromosome inactivation. Nature. 1996.",
      "doi": "10.1038/379131a0",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/8538762/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/8538762/",
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      "study_id": "PMID8538762",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse gene-targeted Xist deletion",
      "decisive_perturbation": true,
      "endogenous": true,
      "direction": "supporting",
      "what_it_shows": "Xist gene targeting demonstrates requirement for normal XCI.",
      "what_it_does_not_show": "The abstract is brief and gives no direct Polycomb-scaffold test; no complete body audit here.",
      "confounders_present": [
        "The abstract is brief and gives no direct Polycomb-scaffold test; no complete body audit here."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 45,
      "pmid": "35584662",
      "title": "Xist-mediated silencing requires additive functions of SPEN and Polycomb together with differentiation-dependent recruitment of SmcHD1.",
      "citation": "Bowness JS, Nesterova TB, Wei G et al. Xist-mediated silencing requires additive functions of SPEN and Polycomb together with differentiation-dependent recruitment of SmcHD1. Cell reports. 2022.",
      "doi": "10.1016/j.celrep.2022.110830",
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      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "Oxford-allelic-Xist-platform",
      "access_depth": "full_text_partial",
      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph0, 1:Results:paragraph18, 1:Results:paragraph19, 1:Results:paragraph20, 1:Results:paragraph21, 1:Results:paragraph26. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [
        "M2"
      ],
      "evidence_class": "Strong",
      "system": "female mouse SPEN-SPOC mutation and PCGF degrons",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Parallel SPEN and Polycomb contributions are separated; combined loss abolishes repression with comparable Xist abundance and RNA-domain controls.",
      "what_it_does_not_show": "Residual localization defects and chromosome-loss selection constrain late endpoints; Polycomb causality does not identify a continuous scaffold.",
      "confounders_present": [
        "Residual localization defects and chromosome-loss selection constrain late endpoints; Polycomb causality does not identify a continuous scaffold."
      ],
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      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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      },
      "shared_components": [
        "Reuses iXist parental platform described in PMID31311937; new SPOC/degron combinations, not a fully independent system."
      ]
    },
    {
      "n": 46,
      "pmid": "40926104",
      "title": "m6A and the NEXT complex direct Xist RNA turnover and X-inactivation dynamics.",
      "citation": "Wei G, Coker H, Rodermund L et al. m6A and the NEXT complex direct Xist RNA turnover and X-inactivation dynamics. Nature structural & molecular biology. 2025.",
      "doi": "10.1038/s41594-025-01663-w",
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      "study_id": "PMID40926104",
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      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse acute METTL3 degron and NEXT perturbation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Acute m6A loss accelerates XCI with increased Xist stability; NEXT-mediated turnover is YTHDC1-independent.",
      "what_it_does_not_show": "This revises m6A-necessity interpretation, not the need for Xist itself or all RNA modifications.",
      "confounders_present": [
        "This revises m6A-necessity interpretation, not the need for Xist itself or all RNA modifications."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 47,
      "pmid": "35301492",
      "title": "Xist spatially amplifies SHARP/SPEN recruitment to balance chromosome-wide silencing and specificity to the X chromosome.",
      "citation": "Jachowicz JW, Strehle M, Banerjee AK et al. Xist spatially amplifies SHARP/SPEN recruitment to balance chromosome-wide silencing and specificity to the X chromosome. Nature structural & molecular biology. 2022.",
      "doi": "10.1038/s41594-022-00739-1",
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        "none_found"
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID35301492",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse SHARP assembly and Xist expression perturbation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Non-stoichiometric SHARP amplification represses regions without direct Xist occupancy; increased RNA also spreads to autosomes.",
      "what_it_does_not_show": "Protein self-assembly need not constitute phase separation or a uniform RNA coat; high expression changes specificity.",
      "confounders_present": [
        "Protein self-assembly need not constitute phase separation or a uniform RNA coat; high expression changes specificity."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 48,
      "pmid": "30787302",
      "title": "Identification of a Xist silencing domain by Tiling CRISPR.",
      "citation": "Wang Y, Zhong Y, Zhou Y et al. Identification of a Xist silencing domain by Tiling CRISPR. Scientific reports. 2019.",
      "doi": "10.1038/s41598-018-36750-0",
      "pmcid": "PMC6382781",
      "url": "https://pubmed.ncbi.nlm.nih.gov/30787302/",
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      "source_tier": "A",
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        "none_found"
      ],
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID30787302",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC1",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse tiling CRISPR",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "A-repeat screening identifies silencing function and effects on Xist transcription.",
      "what_it_does_not_show": "Regulatory DNA/RNA-production effects complicate reading deletions as isolated scaffold lesions.",
      "confounders_present": [
        "Regulatory DNA/RNA-production effects complicate reading deletions as isolated scaffold lesions."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 49,
      "pmid": "34112668",
      "title": "Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading.",
      "citation": "Rodermund L, Coker H, Oldenkamp R et al. Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading. Science (New York, N.Y.). 2021.",
      "doi": "10.1126/science.abe7500",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/34112668/",
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      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "Oxford-allelic-Xist-platform",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse sequential RNA labeling and SPEN perturbation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Old and new RNA couple physically and SPEN affects localization stability and synthesis-degradation feedback.",
      "what_it_does_not_show": "Tagging and optical resolution constrain individual trajectories; dynamics alone cannot define a causal continuous scaffold.",
      "confounders_present": [
        "Tagging and optical resolution constrain individual trajectories; dynamics alone cannot define a causal continuous scaffold."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 50,
      "pmid": "31548724",
      "title": "G-tract RNA removes Polycomb repressive complex 2 from genes.",
      "citation": "Beltran M, Tavares M, Justin N et al. G-tract RNA removes Polycomb repressive complex 2 from genes. Nature structural & molecular biology. 2019.",
      "doi": "10.1038/s41594-019-0293-z",
      "pmcid": "PMC6778522",
      "url": "https://pubmed.ncbi.nlm.nih.gov/31548724/",
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      "tier": "A",
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      "status_flags": [
        "ErratumIn: PMID31695189"
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      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID31548724",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "human mouse RNA targeting and PRC2 biochemistry",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "G-tract RNA competes PRC2 off nucleosomes and targeted CDKN2A RNA releases repression.",
      "what_it_does_not_show": "Other genes and tumor contexts do not imply every Xist interaction is inhibitory; linked correction metadata is retained.",
      "confounders_present": [
        "Other genes and tumor contexts do not imply every Xist interaction is inhibitory; linked correction metadata is retained."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 51,
      "pmid": "28306504",
      "title": "Targeting of Polycomb Repressive Complex 2 to RNA by Short Repeats of Consecutive Guanines.",
      "citation": "Wang X, Goodrich KJ, Gooding AR et al. Targeting of Polycomb Repressive Complex 2 to RNA by Short Repeats of Consecutive Guanines. Molecular cell. 2017.",
      "doi": "10.1016/j.molcel.2017.02.003",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/28306504/",
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      "tier": "A",
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        "none_found"
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID28306504",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "purified human PRC2 and RNA motifs",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "PRC2 preferentially recognizes G tracts and folded quadruplex RNA.",
      "what_it_does_not_show": "Affinity and enrichment cannot establish a native selective Xist tether or causal output.",
      "confounders_present": [
        "Affinity and enrichment cannot establish a native selective Xist tether or causal output."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 52,
      "pmid": "24077223",
      "title": "Promiscuous RNA binding by Polycomb repressive complex 2.",
      "citation": "Davidovich C, Zheng L, Goodrich KJ et al. Promiscuous RNA binding by Polycomb repressive complex 2. Nature structural & molecular biology. 2013.",
      "doi": "10.1038/nsmb.2679",
      "pmcid": "PMC3823624",
      "url": "https://pubmed.ncbi.nlm.nih.gov/24077223/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/24077223/",
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      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID24077223",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "PRC2 affinity assays and genome profiling",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "PRC2 binds relevant and irrelevant RNA with comparable length-dependent affinity.",
      "what_it_does_not_show": "Promiscuity limits specificity inference without excluding regulated contacts in native cells.",
      "confounders_present": [
        "Promiscuity limits specificity inference without excluding regulated contacts in native cells."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 53,
      "pmid": "27197219",
      "title": "The interaction of PRC2 with RNA or chromatin is mutually antagonistic.",
      "citation": "Beltran M, Yates CM, Skalska L et al. The interaction of PRC2 with RNA or chromatin is mutually antagonistic. Genome research. 2016.",
      "doi": "10.1101/gr.197632.115",
      "pmcid": "PMC4937559",
      "url": "https://pubmed.ncbi.nlm.nih.gov/27197219/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/27197219/",
      "tier": "A",
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      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID27197219",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "PRC2 iCLIP cells and competition biochemistry",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "RNA and chromatin/nucleosomes compete for PRC2 and RNA loss alters recruitment patterns.",
      "what_it_does_not_show": "RNase-based chromatin inference requires later normalization controls; competition does not forbid transient RNA-mediated regulation.",
      "confounders_present": [
        "RNase-based chromatin inference requires later normalization controls; competition does not forbid transient RNA-mediated regulation."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 54,
      "pmid": "25601759",
      "title": "Toward a consensus on the binding specificity and promiscuity of PRC2 for RNA.",
      "citation": "Davidovich C, Wang X, Cifuentes-Rojas C et al. Toward a consensus on the binding specificity and promiscuity of PRC2 for RNA. Molecular cell. 2015.",
      "doi": "10.1016/j.molcel.2014.12.017",
      "pmcid": "PMC4320675",
      "url": "https://pubmed.ncbi.nlm.nih.gov/25601759/",
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      "study_id": "PMID25601759",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "human and mouse PRC2 biochemical comparison",
      "decisive_perturbation": false,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "RepA binding and nonspecific RNA binding coexist; assay conditions alter affinities and an examined recruitment interpretation was PRC2-independent.",
      "what_it_does_not_show": "The paper contains experimental binding work despite its title; it does not demonstrate in-vivo motif-specific tethering.",
      "confounders_present": [
        "The paper contains experimental binding work despite its title; it does not demonstrate in-vivo motif-specific tethering."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 55,
      "pmid": "38416645",
      "title": "The apparent loss of PRC2 chromatin occupancy as an artifact of RNA depletion.",
      "citation": "Healy E, Zhang Q, Gail EH et al. The apparent loss of PRC2 chromatin occupancy as an artifact of RNA depletion. Cell reports. 2024.",
      "doi": "10.1016/j.celrep.2024.113858",
      "pmcid": "",
      "url": "https://pubmed.ncbi.nlm.nih.gov/38416645/",
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      "tier": "A",
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      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID38416645",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "RNase-ChIP methodological experiments",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "RNase-induced background DNA redistribution can artifactually reduce PRC2 and H3K27me3 ChIP occupancy.",
      "what_it_does_not_show": "The artifact applies to this assay, not all RNA-binding or recruitment experiments.",
      "confounders_present": [
        "The artifact applies to this assay, not all RNA-binding or recruitment experiments."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 56,
      "pmid": "29185984",
      "title": "Conserved RNA-binding specificity of polycomb repressive complex 2 is achieved by dispersed amino acid patches in EZH2.",
      "citation": "Long Y, Bolanos B, Gong L et al. Conserved RNA-binding specificity of polycomb repressive complex 2 is achieved by dispersed amino acid patches in EZH2. eLife. 2017.",
      "doi": "10.7554/eLife.31558",
      "pmcid": "PMC5706960",
      "url": "https://pubmed.ncbi.nlm.nih.gov/29185984/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/29185984/",
      "tier": "A",
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        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID29185984",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "human fungal PRC2 mutagenesis and HDX-MS",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Dispersed EZH2 residues mediate RNA recognition with conserved quadruplex preference.",
      "what_it_does_not_show": "In-vitro separation of binding does not alone prove Xist-specific silencing and both-complex structural tethering.",
      "confounders_present": [
        "In-vitro separation of binding does not alone prove Xist-specific silencing and both-complex structural tethering."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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      "shared_components": []
    },
    {
      "n": 57,
      "pmid": "29058709",
      "title": "Molecular analysis of PRC2 recruitment to DNA in chromatin and its inhibition by RNA.",
      "citation": "Wang X, Paucek RD, Gooding AR et al. Molecular analysis of PRC2 recruitment to DNA in chromatin and its inhibition by RNA. Nature structural & molecular biology. 2017.",
      "doi": "10.1038/nsmb.3487",
      "pmcid": "PMC5771497",
      "url": "https://pubmed.ncbi.nlm.nih.gov/29058709/",
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      "relates_to_subclaims": [
        "SC2"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "reconstituted human PRC2 nucleosomes DNA RNA",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Linker DNA dominates substrate binding and RNA competitively sequesters PRC2 from nucleosomes.",
      "what_it_does_not_show": "A purified competition model cannot alone settle the full native Xi recruitment cascade.",
      "confounders_present": [
        "A purified competition model cannot alone settle the full native Xi recruitment cascade."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
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    {
      "n": 58,
      "pmid": "18974356",
      "title": "Polycomb proteins targeted by a short repeat RNA to the mouse X chromosome.",
      "citation": "Zhao J, Sun BK, Erwin JA et al. Polycomb proteins targeted by a short repeat RNA to the mouse X chromosome. Science (New York, N.Y.). 2008.",
      "doi": "10.1126/science.1163045",
      "pmcid": "PMC2748911",
      "url": "https://pubmed.ncbi.nlm.nih.gov/18974356/",
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      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse RepA knockdown and recombinant PRC2",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Structured RepA binds recombinant PRC2; knockdown also severely impairs full-length Xist induction, and PRC2-deficient Xist-positive cells can retain silencing.",
      "what_it_does_not_show": "Expression confounding and indirect cellular associations prevent the knockdown from isolating a direct necessary continuous scaffold.",
      "confounders_present": [
        "Expression confounding and indirect cellular associations prevent the knockdown from isolating a direct necessary continuous scaffold."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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        "note": "Provider-indexed aggregate citation counts and selected outgoing references, not an incoming contradiction-body audit or quality score."
      },
      "shared_components": []
    },
    {
      "n": 59,
      "pmid": "16763550",
      "title": "Recruitment of PRC1 function at the initiation of X inactivation independent of PRC2 and silencing.",
      "citation": "Schoeftner S, Sengupta AK, Kubicek S et al. Recruitment of PRC1 function at the initiation of X inactivation independent of PRC2 and silencing. The EMBO journal. 2006.",
      "doi": "10.1038/sj.emboj.7601187",
      "pmcid": "PMC1500994",
      "url": "https://pubmed.ncbi.nlm.nih.gov/16763550/",
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      "opened_on": "2026-10-09",
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      "access_depth": "abstract_metadata",
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      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse Eed-deficient inducible Xist",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "RING1B-dependent H2A ubiquitination persists without EED/H3K27me3 and is independent of silencing.",
      "what_it_does_not_show": "Independent PRC1 recruitment in this context does not imply all PRC complexes act independently in every lineage.",
      "confounders_present": [
        "Independent PRC1 recruitment in this context does not imply all PRC complexes act independently in every lineage."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
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    },
    {
      "n": 60,
      "pmid": "33750950",
      "title": "Independent domains for recruitment of PRC1 and PRC2 by human XIST.",
      "citation": "Dixon-McDougall T, Brown CJ. Independent domains for recruitment of PRC1 and PRC2 by human XIST. PLoS genetics. 2021.",
      "doi": "10.1371/journal.pgen.1009123",
      "pmcid": "PMC8016261",
      "url": "https://pubmed.ncbi.nlm.nih.gov/33750950/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/33750950/",
      "tier": "A",
      "source_tier": "A",
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID33750950",
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      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph0, 1:Results:paragraph7, 1:Results:paragraph10, 1:Results:paragraph13, 1:Results:paragraph14, 1:Results:paragraph16, 1:Results:paragraph18. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "human HT1080 inducible XIST domain deletion",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Different RNA regions and enzymatic inhibitors separate human PRC1/SMCHD1 and PRC2/macroH2A pathways at autosomal and X-linked integration sites.",
      "what_it_does_not_show": "Cancer cells ectopic induction and incomplete global inhibition limit species-general transfer; independence does not demonstrate direct binding.",
      "confounders_present": [
        "Cancer cells ectopic induction and incomplete global inhibition limit species-general transfer; independence does not demonstrate direct binding."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
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    {
      "n": 61,
      "pmid": "40118040",
      "title": "Isogenic comparison of Airn and Xist reveals core principles of Polycomb recruitment by lncRNAs.",
      "citation": "Trotman JB, Abrash EW, Murvin MM et al. Isogenic comparison of Airn and Xist reveals core principles of Polycomb recruitment by lncRNAs. Molecular cell. 2025.",
      "doi": "10.1016/j.molcel.2025.02.014",
      "pmcid": "PMC11932450",
      "url": "https://pubmed.ncbi.nlm.nih.gov/40118040/",
      "source_pointer": "https://pubmed.ncbi.nlm.nih.gov/40118040/",
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID40118040",
      "access_depth": "full_text_partial",
      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph5, 1:Results:paragraph12, 1:Results:paragraph15, 1:Results:paragraph17, 1:Results:paragraph29, 1:Results:paragraph30. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [
        "M2",
        "M4"
      ],
      "evidence_class": "Strong",
      "system": "isogenic mouse ectopic Airn/Xist and native TSC RIP",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Airn deposits Polycomb marks without repression; adding Xist A-repeat restores repression, and native RIP favors hnRNPK-bridged PRC1 association.",
      "what_it_does_not_show": "Formaldehyde RIP detects direct and indirect interactions; weak PRC2 signals do not negate UV-supported contact in a different lineage.",
      "confounders_present": [
        "Formaldehyde RIP detects direct and indirect interactions; weak PRC2 signals do not negate UV-supported contact in a different lineage."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
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    },
    {
      "n": 62,
      "pmid": "38759625",
      "title": "G-quadruplex folding in Xist RNA antagonizes PRC2 activity for stepwise regulation of X chromosome inactivation.",
      "citation": "Lee YW, Weissbein U, Blum R et al. G-quadruplex folding in Xist RNA antagonizes PRC2 activity for stepwise regulation of X chromosome inactivation. Molecular cell. 2024.",
      "doi": "10.1016/j.molcel.2024.04.015",
      "pmcid": "PMC11505738",
      "url": "https://pubmed.ncbi.nlm.nih.gov/38759625/",
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      "tier": "A",
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        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "Lee-Xist-rG4-platform",
      "access_depth": "full_text_partial",
      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:RESULTS:paragraph7, 1:RESULTS:paragraph8, 1:RESULTS:paragraph10, 1:RESULTS:paragraph11, 1:RESULTS:paragraph14, 1:RESULTS:paragraph16. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [
        "M3"
      ],
      "evidence_class": "Strong",
      "system": "mouse native Xist rG4 mutations and UV-RIP",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "rG4 loss preserves direct UV-supported PRC2 association but deregulates marks and silencing; mutants preserving RNA expression avoid the AF confound.",
      "what_it_does_not_show": "A regulated direct contact supports dynamic catalysis, not direct binding to both complexes or continuous structural tethering; assays need independent replication.",
      "confounders_present": [
        "A regulated direct contact supports dynamic catalysis, not direct binding to both complexes or continuous structural tethering; assays need independent replication."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
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      },
      "shared_components": [
        "Lee-laboratory Xist platform; direct-contact assay and mutant evidence need independent replication."
      ]
    },
    {
      "n": 63,
      "pmid": "26195790",
      "title": "The Xist RNA-PRC2 complex at 20-nm resolution reveals a low Xist stoichiometry and suggests a hit-and-run mechanism in mouse cells.",
      "citation": "Sunwoo H, Wu JY, Lee JT. The Xist RNA-PRC2 complex at 20-nm resolution reveals a low Xist stoichiometry and suggests a hit-and-run mechanism in mouse cells. Proceedings of the National Academy of Sciences of the United States of America. 2015.",
      "doi": "10.1073/pnas.1503690112",
      "pmcid": "PMC4534268",
      "url": "https://pubmed.ncbi.nlm.nih.gov/26195790/",
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      "opened_on": "2026-10-09",
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      "study_id": "Lee-Xist-spatial-platform",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Moderate",
      "system": "mouse single-cell STORM and knock-off",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "Sparse Xist/PRC2 hubs and reassociation support a dynamic spatial interaction and hit-and-run model.",
      "what_it_does_not_show": "Nonrandom nanoscale proximity is not itself direct molecular binding; finite detection cannot rule out all undetected RNA.",
      "confounders_present": [
        "Nonrandom nanoscale proximity is not itself direct molecular binding; finite detection cannot rule out all undetected RNA."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    },
    {
      "n": 64,
      "pmid": "31311937",
      "title": "Systematic allelic analysis defines the interplay of key pathways in X chromosome inactivation.",
      "citation": "Nesterova TB, Wei G, Coker H et al. Systematic allelic analysis defines the interplay of key pathways in X chromosome inactivation. Nature communications. 2019.",
      "doi": "10.1038/s41467-019-11171-3",
      "pmcid": "PMC6635394",
      "url": "https://pubmed.ncbi.nlm.nih.gov/31311937/",
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      "study_id": "Oxford-allelic-Xist-platform",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse allelic genetic perturbation models",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "contradicting",
      "what_it_shows": "SPEN dominates many genes while Polycomb supports pre-marked genes; LBR and m6A factors have minor tested contributions.",
      "what_it_does_not_show": "Shared Oxford platforms are not wholly independent replications and gene-class dependence opposes universal scaffold necessity.",
      "confounders_present": [
        "Shared Oxford platforms are not wholly independent replications and gene-class dependence opposes universal scaffold necessity."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
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    {
      "n": 65,
      "pmid": "30827740",
      "title": "Xist Deletional Analysis Reveals an Interdependency between Xist RNA and Polycomb Complexes for Spreading along the Inactive X.",
      "citation": "Colognori D, Sunwoo H, Kriz AJ et al. Xist Deletional Analysis Reveals an Interdependency between Xist RNA and Polycomb Complexes for Spreading along the Inactive X. Molecular cell. 2019.",
      "doi": "10.1016/j.molcel.2019.01.015",
      "pmcid": "PMC6469964",
      "url": "https://pubmed.ncbi.nlm.nih.gov/30827740/",
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      ],
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "Lee-Xist-deletion-platform",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "relates_to_subclaims": [
        "SC2",
        "SC3",
        "SC4"
      ],
      "favors_models": [],
      "evidence_class": "Strong",
      "system": "mouse endogenous repeat deletion and Polycomb ablation",
      "decisive_perturbation": true,
      "endogenous": false,
      "direction": "supporting",
      "what_it_shows": "Repeat B/HNRNPK and Polycomb reciprocally support RNA spreading, silencing and Xi topology.",
      "what_it_does_not_show": "Feedback dependence supports cooperation but does not discriminate a direct continuous tether from adapter recruitment or compaction.",
      "confounders_present": [
        "Feedback dependence supports cooperation but does not discriminate a direct continuous tether from adapter recruitment or compaction."
      ],
      "verification": "verified",
      "verification_note": "Bounded source attribution; not proof of the nominal mechanism.",
      "citation_context": {
        "retrieved": false,
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      "shared_components": []
    }
  ],
  "verification_summary": {
    "load_bearing_claims_checked": 70,
    "verified": 70,
    "unverified": 0,
    "contradicted": 0,
    "note": "Verified attribution is distinct from mechanism truth or complete body access."
  },
  "factual_issues_found": [],
  "cap_rules_applied": [
    {
      "subclaim_id": "SC2",
      "cap": "Γ",
      "cap_source": "rubric",
      "triggered": true,
      "trigger_text_quoted": "Mechanistic plausibility plus in vitro reconstitution or simplified cellular support caps at Γ.",
      "specific_trigger": "Direct PRC2 contact has biochemical and native UV-RIP support, but neither direct binding to both PRCs nor continuous structural tethering is isolated as the silencing mechanism. hnRNPK bridging, PRC1-first catalysis and dynamic release remain better supported. In-vitro contact cannot carry the registered conjunction above Γ.",
      "resulting_ceiling": "Γ"
    },
    {
      "subclaim_id": "SC3",
      "cap": "Γ",
      "cap_source": "rubric",
      "triggered": true,
      "trigger_text_quoted": "Mechanistic plausibility plus in vitro reconstitution or simplified cellular support caps at Γ.",
      "specific_trigger": "Polycomb has causal, gene- and stage-dependent contributions, yet B/C deletion retains substantial initial silencing and matched SPEN/Polycomb loss supports parallel contributions. No positive experiment establishes necessity of a continuous direct scaffold for initiation.",
      "resulting_ceiling": "Γ"
    },
    {
      "subclaim_id": "SC4",
      "cap": "Β",
      "cap_source": "rubric",
      "triggered": true,
      "trigger_text_quoted": "Genome-wide association and colocalization without direct perturbation cap at Β.",
      "specific_trigger": "Population coating and colocalization support broad association only. Sparse calibrated foci, protein amplification and accessible RNAPII argue against reifying a uniform continuous coat. This positive mechanistic subclaim stays at Β; that grade is not a denial of Xist localization.",
      "resulting_ceiling": "Β"
    }
  ],
  "cap_precedence_resolutions": [
    {
      "collision": "Perturbation in a defined setting versus broader inference",
      "subclaim_scope_cap_binds_on": "Xist RNA directly binds and structurally tethers PRC1 and PRC2 across the inactive X chromosome, and this continuous Polycomb scaffold establishes X-linked silencing.",
      "subclaim_scope_threshold_binds_on": "The precise experimentally tested subclaim scope",
      "resolution": "Endogenous deletions/degrons and functional output cross high thresholds for Xist and modular effector subclaims. The simplified-system Γ cap binds transfer from purified PRC2 affinity to the registered direct continuous dual-PRC scaffold. Native opposing results do not become positive Δ evidence merely because the experiment was decisive.",
      "note": "Convergent lines are assessed as a set; one weak leg is not re-capped over the assembled case."
    }
  ],
  "boundary_check_BGD": [
    {
      "subclaim_id": "SC1",
      "field_valid_perturbation_quote": "\n- Endogenous degron of a condensate component with matched rescue, AND evidence that the specific condensate state (not generic protein loss) drives the phenotype\n- Locus-specific disruption of looping with locus-specific effect\n- Combinatorial histone-mark perturbation showing direct output dependence\n- Critically: specificity against cell-cycle collapse, global transcriptional collapse, and replication stress must be demonstrated",
      "qualifying_evidence_present": "yes",
      "qualifying_evidence_citation": "PMID32025035, PMID9009199, PMID10882105, PMID8538762",
      "gamma_hard_rules_triggered": [
        "Direct RNA binding, chromatin marks and a visible RNA cloud are distinct measurements; none alone identifies a continuous causal scaffold.",
        "Native functional perturbations of Xist, SPEN and Polycomb cross thresholds for those narrower pathways; no positive scaffold-specific perturbation crosses SC2/SC3."
      ],
      "disease_phenotype_relevance": "yes",
      "perturbation_result_positive": "yes",
      "perturbation_result_note": "Native Xist deletions with dosage controls, induction sufficiency in defined competent cells and independently identified endogenous SPEN pathways converge on a causal initiating RNA. Human naive dampening and lineage-specific maintenance restrict scope; this is not universal silencing sufficiency in any cell.",
      "ceiling_from_boundary_check": "Δ or higher"
    },
    {
      "subclaim_id": "SC2",
      "field_valid_perturbation_quote": "\n- Endogenous degron of a condensate component with matched rescue, AND evidence that the specific condensate state (not generic protein loss) drives the phenotype\n- Locus-specific disruption of looping with locus-specific effect\n- Combinatorial histone-mark perturbation showing direct output dependence\n- Critically: specificity against cell-cycle collapse, global transcriptional collapse, and replication stress must be demonstrated",
      "qualifying_evidence_present": "no",
      "qualifying_evidence_citation": "",
      "gamma_hard_rules_triggered": [
        "Direct RNA binding, chromatin marks and a visible RNA cloud are distinct measurements; none alone identifies a continuous causal scaffold.",
        "Native functional perturbations of Xist, SPEN and Polycomb cross thresholds for those narrower pathways; no positive scaffold-specific perturbation crosses SC2/SC3."
      ],
      "disease_phenotype_relevance": "yes",
      "perturbation_result_positive": "no",
      "perturbation_result_note": "Direct PRC2 contact has biochemical and native UV-RIP support, but neither direct binding to both PRCs nor continuous structural tethering is isolated as the silencing mechanism. hnRNPK bridging, PRC1-first catalysis and dynamic release remain better supported. In-vitro contact cannot carry the registered conjunction above Γ.",
      "ceiling_from_boundary_check": "Γ"
    },
    {
      "subclaim_id": "SC3",
      "field_valid_perturbation_quote": "\n- Endogenous degron of a condensate component with matched rescue, AND evidence that the specific condensate state (not generic protein loss) drives the phenotype\n- Locus-specific disruption of looping with locus-specific effect\n- Combinatorial histone-mark perturbation showing direct output dependence\n- Critically: specificity against cell-cycle collapse, global transcriptional collapse, and replication stress must be demonstrated",
      "qualifying_evidence_present": "no",
      "qualifying_evidence_citation": "",
      "gamma_hard_rules_triggered": [
        "Direct RNA binding, chromatin marks and a visible RNA cloud are distinct measurements; none alone identifies a continuous causal scaffold.",
        "Native functional perturbations of Xist, SPEN and Polycomb cross thresholds for those narrower pathways; no positive scaffold-specific perturbation crosses SC2/SC3."
      ],
      "disease_phenotype_relevance": "yes",
      "perturbation_result_positive": "no",
      "perturbation_result_note": "Polycomb has causal, gene- and stage-dependent contributions, yet B/C deletion retains substantial initial silencing and matched SPEN/Polycomb loss supports parallel contributions. No positive experiment establishes necessity of a continuous direct scaffold for initiation.",
      "ceiling_from_boundary_check": "Γ"
    },
    {
      "subclaim_id": "SC4",
      "field_valid_perturbation_quote": "\n- Endogenous degron of a condensate component with matched rescue, AND evidence that the specific condensate state (not generic protein loss) drives the phenotype\n- Locus-specific disruption of looping with locus-specific effect\n- Combinatorial histone-mark perturbation showing direct output dependence\n- Critically: specificity against cell-cycle collapse, global transcriptional collapse, and replication stress must be demonstrated",
      "qualifying_evidence_present": "no",
      "qualifying_evidence_citation": "",
      "gamma_hard_rules_triggered": [
        "Direct RNA binding, chromatin marks and a visible RNA cloud are distinct measurements; none alone identifies a continuous causal scaffold.",
        "Native functional perturbations of Xist, SPEN and Polycomb cross thresholds for those narrower pathways; no positive scaffold-specific perturbation crosses SC2/SC3."
      ],
      "disease_phenotype_relevance": "yes",
      "perturbation_result_positive": "no",
      "perturbation_result_note": "Population coating and colocalization support broad association only. Sparse calibrated foci, protein amplification and accessible RNAPII argue against reifying a uniform continuous coat. This positive mechanistic subclaim stays at Β; that grade is not a denial of Xist localization.",
      "ceiling_from_boundary_check": "Γ"
    }
  ],
  "thresholds_tested": [
    {
      "subclaim_id": "SC1",
      "threshold": "Δ",
      "requirement_quoted": "Requires at least one endogenous perturbation showing the proposed feature contributes causally to the claimed output.",
      "satisfied": "yes",
      "supporting_evidence": [
        "[14] SPEN is required for embryonic initiation, disengages after silencing, and SPOC tethering supports repression.",
        "[39] Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects.",
        "[42] Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent.",
        "[44] Xist gene targeting demonstrates requirement for normal XCI."
      ],
      "what_would_cross_it": ""
    },
    {
      "subclaim_id": "SC1",
      "threshold": "Ε",
      "requirement_quoted": "Requires context-specific causality with clear scope restriction. Many enhancer, condensate, or accessibility claims belong here.",
      "satisfied": "yes",
      "supporting_evidence": [
        "[14] SPEN is required for embryonic initiation, disengages after silencing, and SPOC tethering supports repression.",
        "[39] Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects.",
        "[42] Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent.",
        "[44] Xist gene targeting demonstrates requirement for normal XCI."
      ],
      "what_would_cross_it": ""
    },
    {
      "subclaim_id": "SC1",
      "threshold": "Ζ",
      "requirement_quoted": "Requires:\n- Independent causal tests across loci or systems\n- Specificity beyond global transcriptional collapse\n- Narrowing of key alternatives",
      "satisfied": "yes",
      "supporting_evidence": [
        "[14] SPEN is required for embryonic initiation, disengages after silencing, and SPOC tethering supports repression.",
        "[39] Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects.",
        "[42] Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent.",
        "[44] Xist gene targeting demonstrates requirement for normal XCI."
      ],
      "what_would_cross_it": ""
    },
    {
      "subclaim_id": "SC1",
      "threshold": "Η",
      "requirement_quoted": "Requires:\n- Robust endogenous causality\n- Reproducibility across loci/cell states within scope\n- Strong evidence that the proposed mechanism is not a downstream correlate",
      "satisfied": "yes",
      "supporting_evidence": [
        "[14] SPEN is required for embryonic initiation, disengages after silencing, and SPOC tethering supports repression.",
        "[39] Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects.",
        "[42] Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent.",
        "[44] Xist gene targeting demonstrates requirement for normal XCI."
      ],
      "what_would_cross_it": ""
    },
    {
      "subclaim_id": "SC1",
      "threshold": "Θ",
      "requirement_quoted": "Requires broad explanatory power with minimal contradictions.",
      "satisfied": "no",
      "supporting_evidence": [
        "[14] SPEN is required for embryonic initiation, disengages after silencing, and SPOC tethering supports repression.",
        "[39] Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects.",
        "[42] Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent.",
        "[44] Xist gene targeting demonstrates requirement for normal XCI."
      ],
      "what_would_cross_it": "Native graded Xist induction with separation from regulatory-DNA effects and reproducible necessity/sufficiency across the defined lineages would reach Θ/Ω only if major boundaries were explained."
    },
    {
      "subclaim_id": "SC2",
      "threshold": "Δ",
      "requirement_quoted": "Requires at least one endogenous perturbation showing the proposed feature contributes causally to the claimed output.",
      "satisfied": "no",
      "supporting_evidence": [],
      "what_would_cross_it": "Selective endogenous disruption of a direct RNA-PRC1/PRC2 tether while preserving Xist abundance, localization, SPEN and adapter functions, with matched rescue and allele-specific nascent repression."
    },
    {
      "subclaim_id": "SC3",
      "threshold": "Δ",
      "requirement_quoted": "Requires at least one endogenous perturbation showing the proposed feature contributes causally to the claimed output.",
      "satisfied": "no",
      "supporting_evidence": [],
      "what_would_cross_it": "An endogenous scaffold-only lesion must prevent initiation despite intact parallel effectors and restore it upon mechanism-specific rescue."
    },
    {
      "subclaim_id": "SC4",
      "threshold": "Δ",
      "requirement_quoted": "Requires at least one endogenous perturbation showing the proposed feature contributes causally to the claimed output.",
      "satisfied": "no",
      "supporting_evidence": [],
      "what_would_cross_it": "Quantitative single-cell coverage at native expression plus a selective continuity perturbation must connect continuous physical occupancy to functional repression."
    }
  ],
  "generalization_check": {
    "generalization_tested": "yes",
    "context_boundary_mapped": "yes",
    "internal_negative_controls": [
      "Xist ΔA can coat chromatin without silencing; B/C mutations retain RNA while losing Polycomb marks.",
      "GFP-only and hnRNPK ΔKI tethers fail recruitment rescue.",
      "SPEN-SPOC plus targeted RNA PID deletion controls for global PCGF depletion effects.",
      "rG4 AF mutations alter expression and were not used as clean separation-of-function evidence; 3-prime mutations preserve expression."
    ],
    "note": "Initiation/maintenance, gene classes, female XX versus induced XY cells, mouse/human domains and RNA dose are observed boundaries. They are defined from design and not retrospectively by responders. Human somatic redundancy and B-cell continuous XIST dependence cannot be collapsed into one maintenance rule."
  },
  "falsification_patterns_met": [
    {
      "pattern": "Perturbing the proposed feature leaves substantial output intact",
      "evidence": "PMID31456285 B/C loss removes global Polycomb deposition while retaining most early repression; PMID35584662 restricts interpretation to parallel and partial contributions.",
      "downgrade_applied": false
    },
    {
      "pattern": "Spatial continuous-coat inference fails quantitative testing",
      "evidence": "PMIDs34813726,35301492,26195790 show sparse RNA and amplified protein action. Finite imaging cannot exclude every undetected RNA.",
      "downgrade_applied": false
    }
  ],
  "pitfalls_flagged": [
    {
      "pitfall": "Binding treated as regulation",
      "where": "RepA EMSA and UV-RIP contact cannot independently identify a necessary continuous scaffold."
    },
    {
      "pitfall": "Puncta and mark enrichment treated as mechanism",
      "where": "Low-resolution Xist clouds and H3K27me3 do not establish simultaneous chromosome-wide tethering."
    },
    {
      "pitfall": "A simplified rival is overclaimed",
      "where": "A pure serial SPEN-to-PRC cascade is revised by PMID35584662; a categorical no-direct-PRC2-contact conclusion conflicts with PMID38759625."
    }
  ],
  "causal_tally_audit": {
    "tally_claimed_by_document": 56,
    "tally_after_audit": 56,
    "items_rejected": [
      "Null and negative contrasts are discriminators, not positive threshold crossings. Reports and replications are not independent causal lines.",
      "Shared cohorts, experimental platforms, transgenic lineages and repeated outcomes do not constitute fully independent causal lines."
    ]
  },
  "steelman": {
    "case_one_rung_higher": "One-rung-higher Δ steelman: rG4 mutants are native, preserve expression and change repression, while binding assays show direct PRC2 contact. This establishes a regulatory RNA-contact contribution, but the mutations preserve contact and do not isolate continuous structural tethering of both complexes. The registered SC2 mechanism therefore lacks its positive Δ crossing.",
    "case_one_rung_lower": "One-rung-lower Β steelman: promiscuous binding and sparse foci make the scaffold only descriptive. Direct biochemical and UV-supported contacts plus functional RNA-structure perturbations provide genuine mechanistic support, so Γ remains more informative for SC2 despite rejecting its complete conjunction.",
    "which_rejected": "Retain Γ: neither a narrower dynamic-contact success nor rejection of uniform coating can substitute for the registered dual-PRC scaffold.",
    "blocking_cap_threshold_or_missing_experiment": "Missing experiment: At native female Xist expression, selectively disrupt a mapped direct RNA interface for each PRC while preserving SPEN, hnRNPK, RNA abundance and localization; compare initiation with expression-matched interface rescue and acute nascent allele-specific transcription."
  },
  "final_score": {
    "hsef_level": "Γ",
    "hsef_descriptor": "Mechanistically plausible, partial system support",
    "confidence": "Moderate",
    "confidence_rationale": "Many independent perturbation studies across mouse and human systems, but platform-dependent contradictions on direct PRC2 contact (UV-crosslink RIP versus formaldehyde RIP), model-based labelling assumptions in the quantitative imaging, ectopic cancer-cell systems for the human domain work and unaudited correction bodies limit reproducibility. Access depth is not a determinant. Confidence reflects evidence density and reproducibility, not correctness.",
    "rests_on_non_peer_reviewed_work": false,
    "rationale": "The preregistered primary-subclaim rule uses SC2, giving Γ for direct continuous Polycomb scaffolding. SC1 is Η within initiation-competent mammalian contexts, while SC3 is Γ and SC4 Β for their stronger mechanism claims. Weakest-link sensitivity is Β. Evidence for Xist necessity and modular Polycomb causality is retained and cannot replace the nominal structural claim."
  },
  "role_of_mechanism": {
    "classification": "epiphenomenon",
    "derivation_step_matched": 2,
    "derivation": "Step 1 does not establish that silencing produces a continuous dual-PRC RNA tether. At step 2, the proposed continuous scaffold has no isolated causal dependency in either direction, so the framework labels that descriptive structural claim epiphenomenon. This assignment explicitly does not apply to Xist itself, whose initiating causal role is strongly supported, or to the causal Polycomb effector arm.",
    "tournament_used_as_tiebreaker": false,
    "note": "Derived from causal direction, not tournament rank."
  },
  "extended_scoring_MSD": {
    "momentum": {
      "value": "Mechanistic only",
      "artifact": "Lee 2024 tests rG4 regulation and Trotman 2025 tests adapter recruitment; Wei 2025 tests RNA turnover. No verified ongoing experiment isolates the registered continuous dual-PRC tether.",
      "justification": "Lee 2024 tests rG4 regulation and Trotman 2025 tests adapter recruitment; Wei 2025 tests RNA turnover. No verified ongoing experiment isolates the registered continuous dual-PRC tether."
    },
    "stability": {
      "value": "Stable",
      "trigger": "No named pending result is asserted to be likely to move the registered score imminently.",
      "justification": "No named pending result is asserted to be likely to move the registered score imminently."
    },
    "divergence": {
      "implied_level": null,
      "implied_level_basis": "No single field-implied level is defensible from conflicting framings.",
      "assessed_level": "Γ",
      "gap_in_rungs": null,
      "value": "Contested",
      "justification": "No manufactured field consensus or arithmetic gap."
    },
    "calibration_note": "M/S/D never modify HSEF level or confidence."
  },
  "change_record": {
    "applies": false,
    "prior_level": "Ranking categorical verdict visible; no prior letter used as a target",
    "prior_confidence": null,
    "prior_source": null,
    "derived_before_consulting_prior": false,
    "new_level": "Γ",
    "direction": "newly assigned",
    "what_moved_it": "Fresh primary evidence appraisal; not blinded.",
    "divergence_from_other_reviewers": null
  },
  "proposed_decisive_experiments": [
    {
      "name": "Registered boundary experiment",
      "experiment": "At native female Xist expression, selectively disrupt a mapped direct RNA interface for each PRC while preserving SPEN, hnRNPK, RNA abundance and localization; compare initiation with expression-matched interface rescue and acute nascent allele-specific transcription.",
      "readout": "RNA occupancy, UV-supported contact, PRC catalytic marks and gene-resolved nascent repression measured separately over initiation",
      "critical_control": "Adapter-binding, RNA-processing, cell-cycle, global transcription and viability controls; wild-type and binding-deficient matched rescue; independent mammalian lineage",
      "supporting_result": "Loss of only the direct tether prevents initiation and native matched rescue restores both contact and repression across defined genes",
      "falsifying_result": "Silencing persists without the direct tether, or rescue restores contact without repression while adapter/effector pathways explain the output"
    }
  ],
  "knowledge_gaps": [
    {
      "name": "Gap 1",
      "statement": "The frequency and functional necessity of direct PRC2 contact differ across UV-RIP and formaldehyde-RIP platforms; reconcile methods in isogenic lineages.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 2",
      "statement": "Map human and mouse domain functions under native expression rather than inferring species differences solely from ectopic cancer cells.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 3",
      "statement": "Separate catalytic release from continuous occupancy using RNA-interface lesions that preserve RNA localization and effector recruitment.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 4",
      "statement": "Determine quantitative RNA coverage with labeling-efficiency and false-negative controls across cell cycles.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 5",
      "statement": "Establish gene-class-specific initiation and maintenance requirements using acute interventions before chromosome-loss selection.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 6",
      "statement": "Resolve m6A loss timing, turnover and transcript-wide confounding in independently replicated native systems.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 7",
      "statement": "Audit the linked Markaki and G-tract correction bodies before a publication-grade whole-paper claim.",
      "relevance": "Limits mechanism identification or scope."
    },
    {
      "name": "Gap 8",
      "statement": "Measure model predictions prospectively; provider gap-grid empty cells are retrieval limitations, not proven absent research.",
      "relevance": "Limits mechanism identification or scope."
    }
  ],
  "review_metadata": {
    "review_date": "2026-10-09",
    "reviewer": "Codex",
    "evidence_base_note": "65 primary reports; literature cutoff 2026-10-09; source examination UTC date 2026-10-09; bounded critical review, not exhaustive systematic review.",
    "literature_tools_available": true,
    "literature_tools_note": "Life Sciences Literature PubMed/Entrez; attempted Europe PMC XML and successful public NCBI PMC direct HTTPS access are separately logged. Signed-in Consensus browser discovery and targeted indexed full-text checks are reconciled with original sections; failed matches and source substitutions remain explicit. Zero Consensus API calls. SciSpace discovery was also used; primary leads were resolved to canonical originals before counting. See scispace-discovery.json.",
    "skill_version": "5.3",
    "validator_run": "exact archived v5.3 validator 2.3; see validator.txt",
    "validator_warnings_addressed": "The index entry was restated as the preregistered causal claim. No real phenomenon is labelled refuted; warning is explicitly justified.",
    "consensus_consistency_audit": "2026-10-09; supplementary provenance/source reconciliation; original grading retained; prior grades visible."
  },
  "is_calibration_entry": {
    "value": false,
    "entry_role": "not_calibration",
    "blind_graded": null,
    "completed_blinded_calibration": false,
    "expected_band_sealed_at": "",
    "target_sha256": "",
    "target_authorship": "not applicable",
    "target_author_saw_review": null,
    "future_run_status": "not prepared",
    "unblinded_reason": "Ranking categorical verdict and index guidance were visible. No completed blinded calibration claimed."
  },
  "upper_ladder_check": {
    "final_level_below_zeta": true,
    "equivalents_considered": [
      {
        "kind": "mendelian_randomization",
        "available": false,
        "why_not_sufficient": "Upper rungs are live without an RCT. Native Xist alleles, endogenous SPEN/PCGF interventions, graded induction, allele-resolved output and orthogonal proteomic/spatial assays justify Η for the narrow initiating-RNA claim and Ζ for modular recruitment. They do not demonstrate the continuous dual-PRC tether. The missing evidence is mechanism isolation and positive native functional rescue, not clinical randomization."
      },
      {
        "kind": "natural_experiment",
        "available": true,
        "why_not_sufficient": "Upper rungs are live without an RCT. Native Xist alleles, endogenous SPEN/PCGF interventions, graded induction, allele-resolved output and orthogonal proteomic/spatial assays justify Η for the narrow initiating-RNA claim and Ζ for modular recruitment. They do not demonstrate the continuous dual-PRC tether. The missing evidence is mechanism isolation and positive native functional rescue, not clinical randomization."
      },
      {
        "kind": "dose_response_across_populations",
        "available": false,
        "why_not_sufficient": "Upper rungs are live without an RCT. Native Xist alleles, endogenous SPEN/PCGF interventions, graded induction, allele-resolved output and orthogonal proteomic/spatial assays justify Η for the narrow initiating-RNA claim and Ζ for modular recruitment. They do not demonstrate the continuous dual-PRC tether. The missing evidence is mechanism isolation and positive native functional rescue, not clinical randomization."
      },
      {
        "kind": "withdrawal_rechallenge",
        "available": false,
        "why_not_sufficient": "Upper rungs are live without an RCT. Native Xist alleles, endogenous SPEN/PCGF interventions, graded induction, allele-resolved output and orthogonal proteomic/spatial assays justify Η for the narrow initiating-RNA claim and Ζ for modular recruitment. They do not demonstrate the continuous dual-PRC tether. The missing evidence is mechanism isolation and positive native functional rescue, not clinical randomization."
      },
      {
        "kind": "therapeutic_perturbation_hard_endpoint",
        "available": false,
        "why_not_sufficient": "Upper rungs are live without an RCT. Native Xist alleles, endogenous SPEN/PCGF interventions, graded induction, allele-resolved output and orthogonal proteomic/spatial assays justify Η for the narrow initiating-RNA claim and Ζ for modular recruitment. They do not demonstrate the continuous dual-PRC tether. The missing evidence is mechanism isolation and positive native functional rescue, not clinical randomization."
      }
    ],
    "convergence_present": true,
    "cap_reapplied_to_convergent_set": false
  },
  "provenance_header": {
    "sources_total": 65,
    "claims_total": 70,
    "claims_verified": 70,
    "claims_unverified": 0,
    "claims_contradicted": 0,
    "tier_a_sources": 65,
    "generated_by": "Codex; HSEF v5.3",
    "gate_passed": true
  },
  "claims": [
    {
      "id": "C1",
      "text": "XIST perturbation supports X-linked dampening and some autosomal targeting in naive cells. Dampening and dispersed localization differ from complete cis silencing; no continuous Polycomb scaffold is isolated.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC4"
      ],
      "source_ns": [
        1
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C2",
      "text": "Interactome and knockdowns identify modular SPEN and hnRNPK functions coupled to differentiation. Crosslinked association does not establish every interactor as a direct RNA binder or continuous tether.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        2
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C3",
      "text": "Direct SHARP association and HDAC3/SMRT perturbation connect Xist to transcriptional repression and Pol II loss. PRC2 recruitment dependence on this pathway does not itself prove direct Xist-PRC2 contact or a single serial cascade.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        3
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C4",
      "text": "EZH2 and SUZ12 bind RNA directly with length and substrate preferences. Biochemical binding is not native selective tethering of both Polycomb complexes.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        4
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C5",
      "text": "An ERV element replaces A-repeat binding to SPEN and supports strictly local cis repression. Local rescue cannot establish full chromosome silencing or Polycomb as the initiating scaffold.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        5
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C6",
      "text": "Repeat perturbations distinguish SPEN-dependent and pre-Polycomb-marked gene classes with different kinetics. Predictive genomic features remain correlates; classes do not imply universal Polycomb necessity.",
      "carries_number": false,
      "load_bearing_for": [
        "SC3"
      ],
      "source_ns": [
        6
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C7",
      "text": "Xist-dependent EED/EZH2 and H3K27 methylation can occur independently of Xist silencing function. Recruitment and methylation are not sufficient for silencing; no continuous tether measured.",
      "carries_number": true,
      "load_bearing_for": [
        "SC3"
      ],
      "source_ns": [
        7
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C8",
      "text": "Calibrated sparse Xist foci nucleate many SPEN molecules; B-repeat loss impairs compaction and especially late silencing. Molecule estimates depend on labeling calibration; local assemblies and protein gradients are not a continuous RNA coat.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC3",
        "SC4"
      ],
      "source_ns": [
        8
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph2, 1:Results:paragraph3, 1:Results:paragraph4, 1:Results:paragraph11, 1:Results:paragraph12, 1:Results:paragraph17, 1:Results:paragraph18. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C9",
      "text": "RNA abundance, architecture and autonomously Polycomb-binding CpG islands shape broad modification domains. Other lncRNAs and correlated domain patterns cannot alone identify the Xist recruitment mechanism.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC4"
      ],
      "source_ns": [
        9
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C10",
      "text": "XIST coprecipitates with macroH2A and hypoacetylated chromatin. Chromatin association can be indirect and does not resolve a uniform RNA-Polycomb tether.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC4"
      ],
      "source_ns": [
        10
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C11",
      "text": "XIST promoter deletion reduces Polycomb marks without appreciable gene reactivation in the tested cells. Maintenance redundancy is lineage-specific; it does not erase XIST initiation necessity.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        11
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C12",
      "text": "PCGF3/5 double loss abolishes Xi Polycomb marks and compromises silencing; single-loss controls and embryos support a PRC1-first route. Global PCGF loss and transgenic induction are not a direct RNA interface-specific test; phenotype does not prove PRC2-first scaffolding.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        12
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Main text:paragraph9, 1:Main text:paragraph10, 1:Main text:paragraph11, 1:Main text:paragraph12. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C13",
      "text": "HDAC3 activity and early deacetylation accompany silencing before Polycomb spreads into genes. Temporal order and HDAC3 perturbation do not require that all Polycomb activity lies downstream of SPEN.",
      "carries_number": true,
      "load_bearing_for": [
        "SC3"
      ],
      "source_ns": [
        13
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C14",
      "text": "SPEN is required for embryonic initiation, disengages after silencing, and SPOC tethering supports repression. SPEN is dispensable for much neural maintenance; total SPEN loss also alters RNA localization and does not isolate its effector domain.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC2",
        "SC3"
      ],
      "source_ns": [
        14
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C15",
      "text": "Silent Xi persists without EED in undifferentiated cells but reactivates upon differentiation. A differentiation-dependent memory role is not general Polycomb dispensability at initiation.",
      "carries_number": false,
      "load_bearing_for": [
        "SC3"
      ],
      "source_ns": [
        15
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C16",
      "text": "SPEN loss impairs Xist upregulation and concomitant Tsix removal rescues that defect. Silencing failure after SPEN loss partly reflects altered Xist abundance rather than only downstream repression.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        16
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C17",
      "text": "Xist regulatory-region disruption and cohesin degradation link stage-specific megadomains to local regulation. Chromosome folding boundaries are not direct Polycomb tethers and may be strain-specific.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC4"
      ],
      "source_ns": [
        17
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C18",
      "text": "Whole XIST deletion reactivates genes; segmental deletion maps maintenance functions including exon 5. A cancer cell line and maintenance context cannot fix all human developmental domains or the direct PRC binding interface.",
      "carries_number": true,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        18
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C19",
      "text": "RNAPII can enter the Xist territory; apparent depletion reflects reduced chromatin-bound transcription machinery. Accessible diffusion does not exclude all local protein assemblies or every mature Xi physical effect.",
      "carries_number": false,
      "load_bearing_for": [
        "SC4"
      ],
      "source_ns": [
        19
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C20",
      "text": "Mutant Xist coats the X yet establishes incomplete and unstable silencing. Coating is insufficient; the allele perturbs more than a selective Polycomb interface.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        20
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C21",
      "text": "SMCHD1 recruitment depends on the Xist-hnRNPK-PRC1/H2AK119ub pathway and lacks specific RNA binding in assays. This supports indirect downstream recruitment rather than proving PRC2 never contacts Xist.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        21
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C22",
      "text": "Xist is a conserved nuclear untranslated repeat-containing transcript expressed from Xi. Localization and sequence conservation are discovery evidence, not silencing causality or scaffold necessity.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC4"
      ],
      "source_ns": [
        22
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C23",
      "text": "Xist spreading exploits pre-existing 3D proximity and its silencing domain to access active regions. Population occupancy maps do not show simultaneous uniform coverage in individual cells.",
      "carries_number": true,
      "load_bearing_for": [
        "SC4"
      ],
      "source_ns": [
        23
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C24",
      "text": "Comparable Xist induction/coating yields sex- and X-dose-dependent differences in silencing. Coating alone is insufficient; ectopic Tsix-driven expression does not represent every normal initiation condition.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC4"
      ],
      "source_ns": [
        24
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C25",
      "text": "A-repeat regulates spliced Xist accumulation and random choice. A-repeat deletion has an RNA-processing confound and cannot be read solely as selective PRC2 binding loss.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        25
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C26",
      "text": "B/C-deficient Xist retains silencing despite loss of H3K27me3 and H4K20me1 accumulation. Retained initiation does not exclude stabilization or gene-specific Polycomb dependence.",
      "carries_number": true,
      "load_bearing_for": [
        "SC3",
        "SC4"
      ],
      "source_ns": [
        26
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C27",
      "text": "hnRNPK directly bridges B-repeat to PCGF3-PRC1; KI-deficient and GFP tether controls fail while hnRNPK restores marks and silencing. Synthetic tethering is a mechanistic rescue within engineered cells, not proof of a direct continuous RNA interaction with both PRCs.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        27
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph44, 1:Results:paragraph49, 1:Results:paragraph50, 1:Results:paragraph51, 1:Results:paragraph60, 1:Results:paragraph61, 1:Results:paragraph62. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C28",
      "text": "Orthogonal RNA structure and interaction methods plus A-repeat relocation show modular RNP architecture. A structured modular RNA is not automatically a chromosome-wide Polycomb scaffold.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        28
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C29",
      "text": "B/C loss removes PCGF3/5 association and global marks while most initial silencing persists; RNA stability/coating and A-repeat controls distinguish effects. Induced XY expression exceeds native maintenance signal and residual promoter marks remain; modest silencing deficits cannot be described as zero Polycomb function.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        29
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph0, 1:Results:paragraph15, 1:Results:paragraph26, 1:Results:paragraph28, 1:Results:paragraph42, 1:Results:paragraph52, 1:Results:paragraph63. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C30",
      "text": "CIZ1 loss disperses Xist in somatic lineages and re-expression restores focal localization. Anchoring to a matrix is not direct binding of Xist to both PRCs; viable mutants restrict universality.",
      "carries_number": true,
      "load_bearing_for": [
        "SC4"
      ],
      "source_ns": [
        30
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C31",
      "text": "Cohesin loss greatly changes Xi structure with little repression change, whereas retention disrupts Xist spreading and silencing. Structure-function dependence is asymmetric and cannot be reduced to all structural perturbations causing transcription loss.",
      "carries_number": false,
      "load_bearing_for": [
        "SC3",
        "SC4"
      ],
      "source_ns": [
        31
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C32",
      "text": "Repeat E/CIZ1 loss and CIZ1 overexpression disperse Xist with reduced H3K27me3. Dose-sensitive local anchoring does not establish continuous chromosome-wide RNA occupancy.",
      "carries_number": true,
      "load_bearing_for": [
        "SC4"
      ],
      "source_ns": [
        32
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C33",
      "text": "Broad Xist interactome and multi-factor inhibition reveal layered repression and cohesin eviction. Association/proteomic sensitivity and multi-target intervention do not identify a unique direct PRC scaffold.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC3",
        "SC4"
      ],
      "source_ns": [
        33
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C34",
      "text": "SMCHD1 loss preserves intermediate compartments, impairs regional Xist spread and silencing. Architectural contribution is downstream or cooperative, not continuous direct Xist-PRC tethering.",
      "carries_number": true,
      "load_bearing_for": [
        "SC3",
        "SC4"
      ],
      "source_ns": [
        34
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C35",
      "text": "SPEN RBM15 and WTAP perturbations impair establishment and factors colocalize with Xist. shRNA and colocalization can involve RNA abundance or indirect effects; later acute m6A tests revise necessity.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        35
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C36",
      "text": "Multiple hnRNPK domains and RNA conformation determine B-motif binding affinity. C-patch preference is not sufficient to predict every cellular binding site; isolated affinity does not establish continuous occupancy.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        36
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C37",
      "text": "m6A machinery knockdown impairs XIST repression and synthetic YTHDC1 tethering rescues it. Transcript-wide effects and engineered rescue do not establish native m6A necessity; acute METTL3 depletion produces a different result.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        37
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C38",
      "text": "XIST continuously restrains a subset of immune genes through lineage-specific repression with TRIM28. B-cell maintenance differs from diploid somatic redundancy; continual XIST requirement is not a continuous Polycomb scaffold.",
      "carries_number": true,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        38
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C39",
      "text": "Parent-of-origin deletion gives dosage-compensation failure and female embryonic lethality; XO and male controls resolve dosage effects. These controls establish Xist function without distinguishing direct PRC tethering from modular recruitment.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1"
      ],
      "source_ns": [
        39
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C40",
      "text": "Xist expression precedes XCI and shows developmental imprinting. Temporal precedence without perturbation cannot establish necessary scaffold action.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1"
      ],
      "source_ns": [
        40
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C41",
      "text": "Conserved locus and exclusive Xi expression identify a candidate dosage-compensation RNA. Mapping and association alone do not show causality.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1"
      ],
      "source_ns": [
        41
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C42",
      "text": "Xist initiates long-range cis repression within a developmental window and later repression becomes less Xist-dependent. Ectopic sufficiency is context-limited; irreversible maintenance does not require continuous RNA scaffold persistence.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        42
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C43",
      "text": "A-repeat loss preserves localization/spreading but abolishes silencing, separating functions. Engineered cDNA-domain behavior cannot alone identify native PRC recruitment interfaces.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3",
        "SC4"
      ],
      "source_ns": [
        43
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C44",
      "text": "Xist gene targeting demonstrates requirement for normal XCI. The abstract is brief and gives no direct Polycomb-scaffold test; no complete body audit here.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1"
      ],
      "source_ns": [
        44
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C45",
      "text": "Parallel SPEN and Polycomb contributions are separated; combined loss abolishes repression with comparable Xist abundance and RNA-domain controls. Residual localization defects and chromosome-loss selection constrain late endpoints; Polycomb causality does not identify a continuous scaffold.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        45
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph0, 1:Results:paragraph18, 1:Results:paragraph19, 1:Results:paragraph20, 1:Results:paragraph21, 1:Results:paragraph26. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C46",
      "text": "Acute m6A loss accelerates XCI with increased Xist stability; NEXT-mediated turnover is YTHDC1-independent. This revises m6A-necessity interpretation, not the need for Xist itself or all RNA modifications.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2",
        "SC3"
      ],
      "source_ns": [
        46
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C47",
      "text": "Non-stoichiometric SHARP amplification represses regions without direct Xist occupancy; increased RNA also spreads to autosomes. Protein self-assembly need not constitute phase separation or a uniform RNA coat; high expression changes specificity.",
      "carries_number": false,
      "load_bearing_for": [
        "SC2",
        "SC4"
      ],
      "source_ns": [
        47
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C48",
      "text": "A-repeat screening identifies silencing function and effects on Xist transcription. Regulatory DNA/RNA-production effects complicate reading deletions as isolated scaffold lesions.",
      "carries_number": false,
      "load_bearing_for": [
        "SC1",
        "SC3"
      ],
      "source_ns": [
        48
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C49",
      "text": "Old and new RNA couple physically and SPEN affects localization stability and synthesis-degradation feedback. Tagging and optical resolution constrain individual trajectories; dynamics alone cannot define a causal continuous scaffold.",
      "carries_number": false,
      "load_bearing_for": [
        "SC4"
      ],
      "source_ns": [
        49
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C50",
      "text": "G-tract RNA competes PRC2 off nucleosomes and targeted CDKN2A RNA releases repression. Other genes and tumor contexts do not imply every Xist interaction is inhibitory; linked correction metadata is retained.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        50
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C51",
      "text": "PRC2 preferentially recognizes G tracts and folded quadruplex RNA. Affinity and enrichment cannot establish a native selective Xist tether or causal output.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        51
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C52",
      "text": "PRC2 binds relevant and irrelevant RNA with comparable length-dependent affinity. Promiscuity limits specificity inference without excluding regulated contacts in native cells.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        52
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C53",
      "text": "RNA and chromatin/nucleosomes compete for PRC2 and RNA loss alters recruitment patterns. RNase-based chromatin inference requires later normalization controls; competition does not forbid transient RNA-mediated regulation.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        53
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C54",
      "text": "RepA binding and nonspecific RNA binding coexist; assay conditions alter affinities and an examined recruitment interpretation was PRC2-independent. The paper contains experimental binding work despite its title; it does not demonstrate in-vivo motif-specific tethering.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        54
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C55",
      "text": "RNase-induced background DNA redistribution can artifactually reduce PRC2 and H3K27me3 ChIP occupancy. The artifact applies to this assay, not all RNA-binding or recruitment experiments.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        55
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C56",
      "text": "Dispersed EZH2 residues mediate RNA recognition with conserved quadruplex preference. In-vitro separation of binding does not alone prove Xist-specific silencing and both-complex structural tethering.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        56
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C57",
      "text": "Linker DNA dominates substrate binding and RNA competitively sequesters PRC2 from nucleosomes. A purified competition model cannot alone settle the full native Xi recruitment cascade.",
      "carries_number": true,
      "load_bearing_for": [
        "SC2"
      ],
      "source_ns": [
        57
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C58",
      "text": "Structured RepA binds recombinant PRC2; knockdown also severely impairs full-length Xist induction, and PRC2-deficient Xist-positive cells can retain silencing. Expression confounding and indirect cellular associations prevent the knockdown from isolating a direct necessary continuous scaffold.",
      "carries_number": true,
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      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Main text:paragraph7, 1:Main text:paragraph8, 1:Main text:paragraph9, 1:Main text:paragraph10, 1:Main text:paragraph11. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C59",
      "text": "RING1B-dependent H2A ubiquitination persists without EED/H3K27me3 and is independent of silencing. Independent PRC1 recruitment in this context does not imply all PRC complexes act independently in every lineage.",
      "carries_number": true,
      "load_bearing_for": [
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        "SC3"
      ],
      "source_ns": [
        59
      ],
      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C60",
      "text": "Different RNA regions and enzymatic inhibitors separate human PRC1/SMCHD1 and PRC2/macroH2A pathways at autosomal and X-linked integration sites. Cancer cells ectopic induction and incomplete global inhibition limit species-general transfer; independence does not demonstrate direct binding.",
      "carries_number": true,
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      "source_ns": [
        60
      ],
      "verification": "verified",
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C61",
      "text": "Airn deposits Polycomb marks without repression; adding Xist A-repeat restores repression, and native RIP favors hnRNPK-bridged PRC1 association. Formaldehyde RIP detects direct and indirect interactions; weak PRC2 signals do not negate UV-supported contact in a different lineage.",
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      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph5, 1:Results:paragraph12, 1:Results:paragraph15, 1:Results:paragraph17, 1:Results:paragraph29, 1:Results:paragraph30. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C62",
      "text": "rG4 loss preserves direct UV-supported PRC2 association but deregulates marks and silencing; mutants preserving RNA expression avoid the AF confound. A regulated direct contact supports dynamic catalysis, not direct binding to both complexes or continuous structural tethering; assays need independent replication.",
      "carries_number": true,
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C63",
      "text": "Sparse Xist/PRC2 hubs and reassociation support a dynamic spatial interaction and hit-and-run model. Nonrandom nanoscale proximity is not itself direct molecular binding; finite detection cannot rule out all undetected RNA.",
      "carries_number": true,
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      "verification": "verified",
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C64",
      "text": "SPEN dominates many genes while Polycomb supports pre-marked genes; LBR and m6A factors have minor tested contributions. Shared Oxford platforms are not wholly independent replications and gene-class dependence opposes universal scaffold necessity.",
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      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "C65",
      "text": "Repeat B/HNRNPK and Polycomb reciprocally support RNA spreading, silencing and Xi topology. Feedback dependence supports cooperation but does not discriminate a direct continuous tether from adapter recruitment or compaction.",
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      "load_bearing_for": [
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      "verification": "verified",
      "verified_against": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "CSC1",
      "text": "Native Xist deletions with dosage controls, induction sufficiency in defined competent cells and independently identified endogenous SPEN pathways converge on a causal initiating RNA. Human naive dampening and lineage-specific maintenance restrict scope; this is not universal silencing sufficiency in any cell.",
      "carries_number": false,
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "CSC2",
      "text": "Direct PRC2 contact has biochemical and native UV-RIP support, but neither direct binding to both PRCs nor continuous structural tethering is isolated as the silencing mechanism. hnRNPK bridging, PRC1-first catalysis and dynamic release remain better supported. In-vitro contact cannot carry the registered conjunction above Γ.",
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      "load_bearing_for": [
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "CSC3",
      "text": "Polycomb has causal, gene- and stage-dependent contributions, yet B/C deletion retains substantial initial silencing and matched SPEN/Polycomb loss supports parallel contributions. No positive experiment establishes necessity of a continuous direct scaffold for initiation.",
      "carries_number": false,
      "load_bearing_for": [
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      ],
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "CSC4",
      "text": "Population coating and colocalization support broad association only. Sparse calibrated foci, protein amplification and accessible RNAPII argue against reifying a uniform continuous coat. This positive mechanistic subclaim stays at Β; that grade is not a denial of Xist localization.",
      "carries_number": false,
      "load_bearing_for": [
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      ],
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      ],
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      "verified_on": "2026-10-09",
      "note": ""
    },
    {
      "id": "CH",
      "text": "Xist is a causal silencing RNA, but direct continuous tethering of both Polycomb complexes is not established.",
      "carries_number": false,
      "load_bearing_for": [
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      ],
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      "note": ""
    }
  ],
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    {
      "n": 1,
      "citation": "Dror I, Chitiashvili T, Tan SYX et al. XIST directly regulates X-linked and autosomal genes in naive human pluripotent cells. Cell. 2024.",
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        "CSC4"
      ]
    },
    {
      "n": 2,
      "citation": "Chu C, Zhang QC, da Rocha ST et al. Systematic discovery of Xist RNA binding proteins. Cell. 2015.",
      "tier": "A",
      "kind": "primary",
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      "doi": "10.1016/j.cell.2015.03.025",
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        "C2",
        "CSC2",
        "CSC3"
      ]
    },
    {
      "n": 3,
      "citation": "McHugh CA, Chen CK, Chow A et al. The Xist lncRNA interacts directly with SHARP to silence transcription through HDAC3. Nature. 2015.",
      "tier": "A",
      "kind": "primary",
      "pmid": "25915022",
      "doi": "10.1038/nature14443",
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        "C3",
        "CSC2",
        "CSC3"
      ]
    },
    {
      "n": 4,
      "citation": "Betancur JG, Tomari Y. Cryptic RNA-binding by PRC2 components EZH2 and SUZ12. RNA biology. 2015.",
      "tier": "A",
      "kind": "primary",
      "pmid": "26177152",
      "doi": "10.1080/15476286.2015.1069463",
      "url": "https://pubmed.ncbi.nlm.nih.gov/26177152/",
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        "C4",
        "CSC2"
      ]
    },
    {
      "n": 5,
      "citation": "Carter AC, Xu J, Nakamoto MY et al. Spen links RNA-mediated endogenous retrovirus silencing and X chromosome inactivation. eLife. 2020.",
      "tier": "A",
      "kind": "primary",
      "pmid": "32379046",
      "doi": "10.7554/eLife.54508",
      "url": "https://pubmed.ncbi.nlm.nih.gov/32379046/",
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      "carries_claims": [
        "C5",
        "CSC2",
        "CSC3"
      ]
    },
    {
      "n": 6,
      "citation": "Barros de Andrade E Sousa L, Jonkers I, Syx L et al. Kinetics of Xist-induced gene silencing can be predicted from combinations of epigenetic and genomic features. Genome research. 2019.",
      "tier": "A",
      "kind": "primary",
      "pmid": "31175153",
      "doi": "10.1101/gr.245027.118",
      "url": "https://pubmed.ncbi.nlm.nih.gov/31175153/",
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      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C6",
        "CSC3"
      ]
    },
    {
      "n": 7,
      "citation": "Plath K, Fang J, Mlynarczyk-Evans SK et al. Role of histone H3 lysine 27 methylation in X inactivation. Science (New York, N.Y.). 2003.",
      "tier": "A",
      "kind": "primary",
      "pmid": "12649488",
      "doi": "10.1126/science.1084274",
      "url": "https://pubmed.ncbi.nlm.nih.gov/12649488/",
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      "study_id": "PMID12649488",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C7",
        "CSC3"
      ]
    },
    {
      "n": 8,
      "citation": "Markaki Y, Gan Chong J, Wang Y et al. Xist nucleates local protein gradients to propagate silencing across the X chromosome. Cell. 2021.",
      "tier": "A",
      "kind": "primary",
      "pmid": "34813726",
      "doi": "10.1016/j.cell.2021.10.022",
      "url": "https://pubmed.ncbi.nlm.nih.gov/34813726/",
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      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID34813726",
      "access_depth": "full_text_partial",
      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Results:paragraph2, 1:Results:paragraph3, 1:Results:paragraph4, 1:Results:paragraph11, 1:Results:paragraph12, 1:Results:paragraph17, 1:Results:paragraph18. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C8",
        "CSC2",
        "CSC3",
        "CSC4",
        "CH"
      ]
    },
    {
      "n": 9,
      "citation": "Schertzer MD, Braceros KCA, Starmer J et al. lncRNA-Induced Spread of Polycomb Controlled by Genome Architecture, RNA Abundance, and CpG Island DNA. Molecular cell. 2019.",
      "tier": "A",
      "kind": "primary",
      "pmid": "31256989",
      "doi": "10.1016/j.molcel.2019.05.028",
      "url": "https://pubmed.ncbi.nlm.nih.gov/31256989/",
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      ],
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      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C9",
        "CSC2",
        "CSC4"
      ]
    },
    {
      "n": 10,
      "citation": "Gilbert SL, Pehrson JR, Sharp PA. XIST RNA associates with specific regions of the inactive X chromatin. The Journal of biological chemistry. 2000.",
      "tier": "A",
      "kind": "primary",
      "pmid": "11006266",
      "doi": "10.1074/jbc.C000409200",
      "url": "https://pubmed.ncbi.nlm.nih.gov/11006266/",
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        "none_found"
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      "study_id": "PMID11006266",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C10",
        "CSC2",
        "CSC4"
      ]
    },
    {
      "n": 11,
      "citation": "Westervelt N, Yoest A, Sayed S et al. Deletion of the XIST promoter from the human inactive X chromosome compromises polycomb heterochromatin maintenance. Chromosoma. 2021.",
      "tier": "A",
      "kind": "primary",
      "pmid": "33745031",
      "doi": "10.1007/s00412-021-00754-z",
      "url": "https://pubmed.ncbi.nlm.nih.gov/33745031/",
      "status_flags": [
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      ],
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      "study_id": "PMID33745031",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C11",
        "CSC1",
        "CSC3"
      ]
    },
    {
      "n": 12,
      "citation": "Almeida M, Pintacuda G, Masui O et al. PCGF3/5-PRC1 initiates Polycomb recruitment in X chromosome inactivation. Science (New York, N.Y.). 2017.",
      "tier": "A",
      "kind": "primary",
      "pmid": "28596365",
      "doi": "10.1126/science.aal2512",
      "url": "https://pubmed.ncbi.nlm.nih.gov/28596365/",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "Oxford-PCGF-Xist-platform",
      "access_depth": "full_text_partial",
      "access_note": "Complete primary abstract and linked-status metadata examined. Selected body sections: 1:Main text:paragraph9, 1:Main text:paragraph10, 1:Main text:paragraph11, 1:Main text:paragraph12. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C12",
        "CSC2",
        "CSC3"
      ]
    },
    {
      "n": 13,
      "citation": "Żylicz JJ, Bousard A, Žumer K et al. The Implication of Early Chromatin Changes in X Chromosome Inactivation. Cell. 2019.",
      "tier": "A",
      "kind": "primary",
      "pmid": "30595450",
      "doi": "10.1016/j.cell.2018.11.041",
      "url": "https://pubmed.ncbi.nlm.nih.gov/30595450/",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID30595450",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C13",
        "CSC3"
      ]
    },
    {
      "n": 14,
      "citation": "Dossin F, Pinheiro I, Żylicz JJ et al. SPEN integrates transcriptional and epigenetic control of X-inactivation. Nature. 2020.",
      "tier": "A",
      "kind": "primary",
      "pmid": "32025035",
      "doi": "10.1038/s41586-020-1974-9",
      "url": "https://pubmed.ncbi.nlm.nih.gov/32025035/",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID32025035",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C14",
        "CSC1",
        "CSC2",
        "CSC3"
      ]
    },
    {
      "n": 15,
      "citation": "Kalantry S, Mills KC, Yee D et al. The Polycomb group protein Eed protects the inactive X-chromosome from differentiation-induced reactivation. Nature cell biology. 2006.",
      "tier": "A",
      "kind": "primary",
      "pmid": "16415857",
      "doi": "10.1038/ncb1351",
      "url": "https://pubmed.ncbi.nlm.nih.gov/16415857/",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID16415857",
      "access_depth": "abstract_metadata",
      "access_note": "Complete primary abstract and linked-status metadata examined. No complete-paper or supplement audit claimed.",
      "carries_claims": [
        "C15",
        "CSC3"
      ]
    },
    {
      "n": 16,
      "citation": "Robert-Finestra T, Tan BF, Mira-Bontenbal H et al. SPEN is required for Xist upregulation during initiation of X chromosome inactivation. Nature communications. 2021.",
      "tier": "A",
      "kind": "primary",
      "pmid": "34853312",
      "doi": "10.1038/s41467-021-27294-5",
      "url": "https://pubmed.ncbi.nlm.nih.gov/34853312/",
      "status_flags": [
        "none_found"
      ],
      "opened": true,
      "opened_on": "2026-10-09",
      "status_checked_on": "2026-10-09",
      "study_id": "PMID34853312",
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    {
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    {
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      "citation": "Royce-Tolland ME, Andersen AA, Koyfman HR et al. The A-repeat links ASF/SF2-dependent Xist RNA processing with random choice during X inactivation. Nature structural & molecular biology. 2010.",
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      "n": 26,
      "citation": "Tjalsma SJD, Hori M, Sato Y et al. H4K20me1 and H3K27me3 are concurrently loaded onto the inactive X chromosome but dispensable for inducing gene silencing. EMBO reports. 2021.",
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      "citation": "Pintacuda G, Wei G, Roustan C et al. hnRNPK Recruits PCGF3/5-PRC1 to the Xist RNA B-Repeat to Establish Polycomb-Mediated Chromosomal Silencing. Molecular cell. 2017.",
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    {
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      "citation": "Ridings-Figueroa R, Stewart ER, Nesterova TB et al. The nuclear matrix protein CIZ1 facilitates localization of Xist RNA to the inactive X-chromosome territory. Genes & development. 2017.",
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    {
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      "citation": "Kriz AJ, Colognori D, Sunwoo H et al. Balancing cohesin eviction and retention prevents aberrant chromosomal interactions, Polycomb-mediated repression, and X-inactivation. Molecular cell. 2021.",
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    {
      "n": 33,
      "citation": "Minajigi A, Froberg J, Wei C et al. Chromosomes. A comprehensive Xist interactome reveals cohesin repulsion and an RNA-directed chromosome conformation. Science (New York, N.Y.). 2015.",
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    {
      "n": 34,
      "citation": "Wang CY, Jégu T, Chu HP et al. SMCHD1 Merges Chromosome Compartments and Assists Formation of Super-Structures on the Inactive X. Cell. 2018.",
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      "citation": "Moindrot B, Cerase A, Coker H et al. A Pooled shRNA Screen Identifies Rbm15, Spen, and Wtap as Factors Required for Xist RNA-Mediated Silencing. Cell reports. 2015.",
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      "citation": "Nakamoto MY, Lammer NC, Batey RT et al. hnRNPK recognition of the B motif of Xist and other biological RNAs. Nucleic acids research. 2020.",
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    {
      "n": 37,
      "citation": "Patil DP, Chen CK, Pickering BF et al. m(6)A RNA methylation promotes XIST-mediated transcriptional repression. Nature. 2016.",
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    {
      "n": 38,
      "citation": "Yu B, Qi Y, Li R et al. B cell-specific XIST complex enforces X-inactivation and restrains atypical B cells. Cell. 2021.",
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    {
      "n": 39,
      "citation": "Marahrens Y, Panning B, Dausman J et al. Xist-deficient mice are defective in dosage compensation but not spermatogenesis. Genes & development. 1997.",
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    {
      "n": 40,
      "citation": "Kay GF, Penny GD, Patel D et al. Expression of Xist during mouse development suggests a role in the initiation of X chromosome inactivation. Cell. 1993.",
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    {
      "n": 41,
      "citation": "Brockdorff N, Ashworth A, Kay GF et al. Conservation of position and exclusive expression of mouse Xist from the inactive X chromosome. Nature. 1991.",
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    {
      "n": 42,
      "citation": "Wutz A, Jaenisch R. A shift from reversible to irreversible X inactivation is triggered during ES cell differentiation. Molecular cell. 2000.",
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    {
      "n": 43,
      "citation": "Wutz A, Rasmussen TP, Jaenisch R. Chromosomal silencing and localization are mediated by different domains of Xist RNA. Nature genetics. 2002.",
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      "doi": "10.1038/ng820",
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      "n": 44,
      "citation": "Penny GD, Kay GF, Sheardown SA et al. Requirement for Xist in X chromosome inactivation. Nature. 1996.",
      "tier": "A",
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    {
      "n": 45,
      "citation": "Bowness JS, Nesterova TB, Wei G et al. Xist-mediated silencing requires additive functions of SPEN and Polycomb together with differentiation-dependent recruitment of SmcHD1. Cell reports. 2022.",
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    {
      "n": 46,
      "citation": "Wei G, Coker H, Rodermund L et al. m6A and the NEXT complex direct Xist RNA turnover and X-inactivation dynamics. Nature structural & molecular biology. 2025.",
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    },
    {
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      "citation": "Jachowicz JW, Strehle M, Banerjee AK et al. Xist spatially amplifies SHARP/SPEN recruitment to balance chromosome-wide silencing and specificity to the X chromosome. Nature structural & molecular biology. 2022.",
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    },
    {
      "n": 48,
      "citation": "Wang Y, Zhong Y, Zhou Y et al. Identification of a Xist silencing domain by Tiling CRISPR. Scientific reports. 2019.",
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      "doi": "10.1038/s41598-018-36750-0",
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    },
    {
      "n": 49,
      "citation": "Rodermund L, Coker H, Oldenkamp R et al. Time-resolved structured illumination microscopy reveals key principles of Xist RNA spreading. Science (New York, N.Y.). 2021.",
      "tier": "A",
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      "pmid": "34112668",
      "doi": "10.1126/science.abe7500",
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    },
    {
      "n": 50,
      "citation": "Beltran M, Tavares M, Justin N et al. G-tract RNA removes Polycomb repressive complex 2 from genes. Nature structural & molecular biology. 2019.",
      "tier": "A",
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    },
    {
      "n": 51,
      "citation": "Wang X, Goodrich KJ, Gooding AR et al. Targeting of Polycomb Repressive Complex 2 to RNA by Short Repeats of Consecutive Guanines. Molecular cell. 2017.",
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      "doi": "10.1016/j.molcel.2017.02.003",
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    },
    {
      "n": 52,
      "citation": "Davidovich C, Zheng L, Goodrich KJ et al. Promiscuous RNA binding by Polycomb repressive complex 2. Nature structural & molecular biology. 2013.",
      "tier": "A",
      "kind": "primary",
      "pmid": "24077223",
      "doi": "10.1038/nsmb.2679",
      "url": "https://pubmed.ncbi.nlm.nih.gov/24077223/",
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        "C52",
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    },
    {
      "n": 53,
      "citation": "Beltran M, Yates CM, Skalska L et al. The interaction of PRC2 with RNA or chromatin is mutually antagonistic. Genome research. 2016.",
      "tier": "A",
      "kind": "primary",
      "pmid": "27197219",
      "doi": "10.1101/gr.197632.115",
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        "C53",
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    },
    {
      "n": 54,
      "citation": "Davidovich C, Wang X, Cifuentes-Rojas C et al. Toward a consensus on the binding specificity and promiscuity of PRC2 for RNA. Molecular cell. 2015.",
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        "C54",
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    },
    {
      "n": 55,
      "citation": "Healy E, Zhang Q, Gail EH et al. The apparent loss of PRC2 chromatin occupancy as an artifact of RNA depletion. Cell reports. 2024.",
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      "kind": "primary",
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    },
    {
      "n": 56,
      "citation": "Long Y, Bolanos B, Gong L et al. Conserved RNA-binding specificity of polycomb repressive complex 2 is achieved by dispersed amino acid patches in EZH2. eLife. 2017.",
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        "C56",
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    },
    {
      "n": 57,
      "citation": "Wang X, Paucek RD, Gooding AR et al. Molecular analysis of PRC2 recruitment to DNA in chromatin and its inhibition by RNA. Nature structural & molecular biology. 2017.",
      "tier": "A",
      "kind": "primary",
      "pmid": "29058709",
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    },
    {
      "n": 58,
      "citation": "Zhao J, Sun BK, Erwin JA et al. Polycomb proteins targeted by a short repeat RNA to the mouse X chromosome. Science (New York, N.Y.). 2008.",
      "tier": "A",
      "kind": "primary",
      "pmid": "18974356",
      "doi": "10.1126/science.1163045",
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    },
    {
      "n": 59,
      "citation": "Schoeftner S, Sengupta AK, Kubicek S et al. Recruitment of PRC1 function at the initiation of X inactivation independent of PRC2 and silencing. The EMBO journal. 2006.",
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    },
    {
      "n": 60,
      "citation": "Dixon-McDougall T, Brown CJ. Independent domains for recruitment of PRC1 and PRC2 by human XIST. PLoS genetics. 2021.",
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      "doi": "10.1371/journal.pgen.1009123",
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    {
      "n": 61,
      "citation": "Trotman JB, Abrash EW, Murvin MM et al. Isogenic comparison of Airn and Xist reveals core principles of Polycomb recruitment by lncRNAs. Molecular cell. 2025.",
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    {
      "n": 62,
      "citation": "Lee YW, Weissbein U, Blum R et al. G-quadruplex folding in Xist RNA antagonizes PRC2 activity for stepwise regulation of X chromosome inactivation. Molecular cell. 2024.",
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        "C63",
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    {
      "n": 64,
      "citation": "Nesterova TB, Wei G, Coker H et al. Systematic allelic analysis defines the interplay of key pathways in X chromosome inactivation. Nature communications. 2019.",
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      "kind": "primary",
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      "doi": "10.1038/s41467-019-11171-3",
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        ],
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