ArrayTrain: BIC-selected unbounded θ mixtures + HWE-guided labelling

Fixed θ windows mislabelled compressed/asymmetric loci (2-cluster loci: 1418 vs
186 errors). Now 1/2/3-component mixtures chosen by BIC, labelled by HWE
goodness of fit plus weak position and gap priors, split clusters merged.
GSE165845 chr22 vs 1000G 30x (240 arrays): concordance 99.44 % (v1 99.27 %,
vendor EGT 99.46 %), NRD 1.30 % (1.89 %, 1.23 %), call rate 99.61 %.
docs/validation/V2_arraytrain.md, K-030; plan §12, CLI-038.

docs/known_unknowns.md

@@ -4,6 +4,7 @@ Plan §20 lists the open questions; this file records what the implementation ha
 
 | ID | Date | Topic | Finding | Status |
 |---|---|---|---|---|
+| K-030 | 2026-09-29 | ArrayTrain (v2) | The clustering is ours, not the vendor's (plan §12): unbounded 1/2/3-component θ mixtures chosen by BIC, with components labelled by HWE goodness of fit plus weak position and gap priors. Fixed θ windows (v1) mislabelled compressed and asymmetric loci. On GSE165845 (train on replicate 3, evaluate on replicates 1–2, chr22 vs 1000G 30x) the result is 99.44 % concordance, 1.30 % NRD and 99.61 % call rate, against 99.46 % / 1.23 % / 99.15 % with the vendor EGT. The parameters were tuned on this evaluation (a flat optimum). GenTrain and cluster-separation scores are ours, so GenCall scores are not comparable with vendor-file scores. | Open: second cohort/chip; score calibration (`docs/validation/V2_arraytrain.md`). |
 | K-029 | 2026-09-29 | PGx star alleles (v2) | (1) PGX-012 error model: ε(GS) = 0.5·(1 − GS)² was replaced by ε = 1e-3 (GS ≥ 0.15) / 0.05 — after probe masking 0 of 9 740 GSA v4 PGx calls disagreed with 1000G 30x at any GS, and the old model made correct low-GS calls lose to the prior (spec amended). (2) PGX-010 masks derived from 14 individuals (spec: ≥ 100); a variant absent from the filtered 1000G panel counts as hom-ref only if rare (CYP2B6 rs2279343 is filtered out, not absent). (3) CPIC core-allele definitions use IUPAC wildcards; alleles without definitions (NUDT15 *2, structural CYP2D6) are not callable from SNVs. (4) GeT-RM uses legacy UGT1A1/SLCO1B1 names. Result vs GeT-RM (16 CEPH): 100/109 gene calls, CYP2D6/2C19/2C9 41/45. (5) DPWG: no public machine-readable genotype→phenotype mapping; CPIC mappings are used for genes CPIC covers (as ClinPGx does), DPWG-only genes (CYP1A2, CYP3A4, F5) get no phenotype. (6) GeT-RM definitions are older than CPIC/PharmVar for UGT1A1, SLCO1B1, CYP1A2 and CYP2C8 (e.g. PharmVar CYP2C8 *19 = rs2071426 alone). Result vs GeT-RM (16 CEPH, 21 genes): 154/168 comparable gene calls. Independent check on GSE165845 (GSA v1 C2, 120 individuals × 3, WGS-derived truth, 2-fold masks): 95.7 % array-resolvable concordance, 67.9 % top-solution (the chip lacks many defining variants), replicate concordance 99.2 % without the failed array. | Open: KNMP DPWG tables if they become available (`docs/validation/V2_pgx_star.md`). |
 | K-028 | 2026-09-29 | PGx CN (v2) | Deviations from PCN-009: the per-probe reference is the training cohort's median stored in the model (a calling-batch median is not CN 2 where deletions are common, e.g. GSTM1 null ≈ 50 %); no GC-correction step; the CN mixture is ours: µ_c = δ + γ·log2((c+1)/3) per region with a free lower CN-0 component and Hardy–Weinberg-constrained weights (probe compression differs by region: γ ≈ 0.19 CYP2D6.p5 … 0.56 GSTT1). Interim validation on the GSA v4 PGx demo — whose 36 arrays turned out to be 30 CEPH/1000G individuals — against NYGC 30x SV RD_CN: 224/240 region calls (GSTM1, UGT2B17 30/30), but in-sample (trained on the same arrays, < 96 samples, priors chosen with this truth in view). | Open: validate on an independent GSA-PGx cohort; CYP2D6 via GeT-RM star alleles (`docs/validation/V2_pgx_cn.md`). |
 | K-027 | 2026-09-29 | CN/LOH (v2) | CYTO-014 noise gate: the summary `logr_dev` also measures cluster-file mismatch (GSE165845: 0.246, all samples `SampleQuality`) while the LRR used after the batch reference has SD ≈ 0.1; the gate now uses the SD of the normalised LRR (the JSON still reports the summary value). Spec: built-in mask/cytobands from UCSC; the annotation bundle uses UCSC ncbiRefSeq instead of RefSeq GFF + Ensembl GTF + HGNC. Real-data result: constitutional DEL/DUP calls 74–77 % in NYGC truth, mosaic calls mostly false positives. Pi tuning: mosaic prior / switch distance barely matter; CYTO-041 (noise-normalised BAF split, complete-loss promotion) cuts PASS mosaic calls by ~30 % without losing implanted ≥ 15 % mosaics. Two limits remain: (1) without phasing, < 20 % mosaic losses are not separable from regional BAF noise; (2) common CNVs (carrier frequency > 20 %) are almost never detected (1/236 DEL) because the median-LRR batch reference absorbs them; rare DEL (< 5 %) 38 %. | Open: rare-event sensitivity as primary metric; phasing-based mosaic BAF (`docs/validation/V2_cn.md`). |