HP1-gamma holds a constitutive, sub-threshold foothold on the KMT2A exon-11 CTCF anchor in undamaged cells - the CTCF-primed model's missing resting state - and the reason nobody has seen it is that it sits below the reproducibility filter every public peak set applies

[
  "At signal level, the exon-11 anchor ranks above the 75th percentile of same-cell-type CTCF anchors for BRCA1 in most interpretable tracks, while the six non-anchor KMT2A intervals stay below the 50th.",
  "The effect is CTCF-dependent: in an acute CTCF-degron line (auxin-inducible, as in ChIP-Atlas SRX11361143/SRX11361144), CBX3 signal at the element falls by more than 2-fold within the degradation window while CBX3 signal averaged over the same cell's other CTCF anchors falls by a similar factor - i.e. the element behaves like its class, not uniquely.",
  "In a haematopoietic cell, a CUT&RUN for CBX3 - which has a far better signal-to-noise floor than crosslinked ChIP and therefore does not need the IDR rescue - calls a peak at the element without any threshold manipulation.",
  "Under damage, the signal at the element rises rather than appearing: a Cas9 break inside chr11:118,482,422-118,489,887 produces a CBX3 increase over the undamaged baseline at the element of at least 2-fold by 15 minutes, rather than a rise from a zero baseline."
]

[
  "exp-idr-free-signal-level-reread-of-the-kmt2a-anchor-across-every-archived-cbx3-and-brca1-track"
]

[
  "ana-q37-the-kmt2a-exon-11-anchor-carries-a-cbx3-and-a-brca1-peak-that-idr-removes",
  "ana-q37-the-resection-layer-outside-encode-a-three-archive-census-with-a-per-protein-absence-class"
]

[
  "CLASS-MATCHED RANK. In a signal-level read of the 45 archived CBX3 tracks, the exon-11 anchor (GRCh38 chr11:118,488,614-118,488,760) sits between the 25th and 75th percentile of 2,000 width- and TSS-distance-matched CTCF anchors of the SAME cell type in the majority of tracks passing the dynamic-range gate. That is 'an ordinary CTCF anchor' and it kills the hypothesis as stated, leaving only the trivially true claim that CBX3 is where CBX3 usually is. Scoreable on public data with no wet work.",
  "BRCA1, THE DISCRIMINATING PROTEIN. BRCA1 occupies only 10.3% of HeLa-S3 CTCF anchors, so its class base rate is low enough to be informative. If the exon-11 anchor's class-matched percentile for BRCA1 is below the 50th in at least 20 of the 31 archived BRCA1 tracks, the foothold claim fails for the protein it most needed to hold for, because a CBX3-only result is indistinguishable from the class base rate.",
  "HAEMATOPOIETIC CUT&RUN. A CBX3 CUT&RUN in an undamaged KMT2A-rearranged B-lineage line (SEM or RS4;11, n >= 2 biological replicates, spike-in normalised) calls NO peak at chr11:118,488,159-118,489,206 at q < 0.01 while calling peaks at >= 20% of that cell's CTCF anchors. A sub-IDR crosslinked-ChIP signal that a higher-signal-to-noise assay cannot see in the disease cell type is a threshold artefact, and the hypothesis should be withdrawn.",
  "THE BASELINE UNDER DAMAGE. At a Cas9 break inside chr11:118,482,422-118,489,887 in a haematopoietic cell, CBX3 ChIP or CUT&RUN signal at the exon-11 anchor at 15 minutes exceeds the undamaged baseline by more than 5-fold. A rise that large from a baseline this beat calls a 'foothold' is recruitment from effectively nothing, and the amplification framing - which is the part of this hypothesis that differs from the existing CTCF-primed model - is wrong even though the occupancy claim may survive.",
  "THE INSTRUMENT ITSELF. If the same IDR-free re-read applied to 20 randomly chosen CTCF anchors in the same tracks recovers sub-threshold peaks at a comparable rate to the KMT2A anchor - specifically, if more than 30% of randomly chosen anchors show a pre-IDR peak that the thresholded file discards - then the observation that generated this hypothesis is a generic property of opening the pre-filter file and carries no information about KMT2A."
]