Is COL9A2 p.Ala23Val (c.68C>T) pathogenic?

COL9A2 p.Ala23Val (c.68C>T) is classified Uncertain significance in COL9A2 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-07-27). AlphaMissense: likely benign (0.2589); Very rare (popmax 0.000344%, nfe).

How common is COL9A2 p.Ala23Val (c.68C>T) in the general population?

COL9A2 p.Ala23Val (c.68C>T) is very rare (popmax 0.000344%, nfe) (gnomAD).

What do computational predictors say about COL9A2 p.Ala23Val (c.68C>T)?

AlphaMissense predicts likely benign (score 0.2589) — an in-silico prediction, not a clinical call.

COL9A2 p.Ala23Val

c.68C>T · VCV4775092

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely benign

0.2589 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.000344%, nfe)

Missense predictors

0/2 damaging

AlphaMissense, SaProt · REVEL no call

Computational evidence

Protein change
AlphaMissense	0.2589	likely benign
REVEL	0.436	indeterminate
SaProt	LLR -8.78	tolerated
⇒ AlphaMissense and SaProt both call this tolerated; REVEL makes no call.
Splicing
SpliceAI	<0.2	all four deltas below 0.2 · G>C here scores Δ0.21 · evaluated, not missing
Constraint at this position
Conservation	phyloP 7.8	GERP 1.6, phastCons 1
Regional constraint	o/e 0.92	unconstrained · MANE · 16 kb · p 0.018 · regional, not allelic
Overall
CADD	24.9	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean tolerated — a triage signal, not a reclassification

AlphaMissense carries the ACMG weight for missense; REVEL and SaProt are independent agreement signals.

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.000344% European (non-Finnish) · 4/1,162,622 alleles

Filtering AF 8.1e-05% ClinGen BA1/BS1 input FAF95, joint · FAF99 5.4e-05%

Overall 0.000253% 4/1,578,254 alleles · very rare

Rarity supports pathogenicity (ACMG PM2); frequency above a disease-specific BA1/BS1 threshold argues against it. A variant frequent in one ancestry group can be near-absent in others, so a single global figure can mislead.

Variant & gene context

Gene: COL9A2
Protein: p.Ala23Val
Coding: c.68C>T
MANE Select: NM_001852
Type: single nucleotide variant
Location: chr1:40317130 (GRCh38)
Gene constraint: LOEUF 0.817 · pLI <0.01 · ClinGen HI 0/3 (gnomAD)
Structure: AlphaFold pLDDT 54.99 · 4 PDB

Full COL9A2 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Similar variants

COL9A2 p.Ala23= Likely benign ★ same residue
COL9A2 c.186+1G>A Pathogenic/Likely pathogenic ★★ same type
COL9A2 p.Arg136Ter Pathogenic/Likely pathogenic ★★ same type
COL9A2 p.Arg504Ter Pathogenic/Likely pathogenic ★★ same type
COL9A2 c.1107+4A>G Uncertain significance ★★ same type
COL9A2 c.1792+5G>A Uncertain significance ★★ same type
COL9A2 c.1793-9T>A Uncertain significance ★★ same type
COL9A2 c.1870+5G>C Uncertain significance ★★ same type

Built on 18 open, versioned datasets — ClinVar, gnomAD, AlphaMissense, REVEL, ClinGen & more — plus Sugi Variant's own cross-source analysis. Source data 2026-01–2026-10, ClinVar 2026-10. Full sources & versions →

Cite Sugi Variant

Gür T. Sugi Variant: A Deterministic Per-Variant Germline Reference from a Knowledge Graph for Humans and AI Agents. 2026. doi:10.5281/zenodo.21509445. This variant: https://sugi.bio/variant/col9a2-p-ala23val (accessed [today's date]).

Preprint & method: sugi.bio/variant/method Machine-readable: this page as Markdown