Is COL9A2 p.Asp77= (c.231C>T) pathogenic?

COL9A2 p.Asp77= (c.231C>T) is classified Likely benign in COL9A2 (ClinVar, Multiple submitters, 3 submitters; last evaluated 2026-01-04). Ultra-rare (popmax 0.0156%, eas).

How common is COL9A2 p.Asp77= (c.231C>T) in the general population?

COL9A2 p.Asp77= (c.231C>T) is ultra-rare (popmax 0.0156%, eas) (gnomAD).

COL9A2 p.Asp77=

c.231C>T · rs372936826 · VCV517920

Likely benign Multiple submitters

Classification

Likely benign

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 3 submitters

gnomAD v4.1

Rare

ultra-rare (popmax 0.0156%, eas)

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
REVEL	0.046	moderately benign-leaning
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP -3.4	GERP -3.5
Overall
CADD	4.796	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0156% East Asian · 7/44,878 alleles

Filtering AF 0.00844% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00661%

Overall 0.00297% 48/1,614,172 alleles · ultra-rare

Ancestry group	Frequency	1 in
Remaining individualsnot grpmax-eligible	0.024%	4,167
East Asiangrpmax	0.0156%	6,411
South Asian	0.0143%	7,007
Admixed American	0.01%	10,005
African / African-American	0.00533%	18,758
European (non-Finnish)	0.000254%	393,340

Remaining individuals shows a higher raw frequency than the grpmax group above it. gnomAD excludes bottlenecked groups — Finnish, Ashkenazi Jewish, Amish and “Remaining individuals” — from grpmax, because founder effects make their frequencies unrepresentative for filtering. The table is sorted by frequency, so an excluded group can sit above the grpmax row.

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.Asp77=
Coding: c.231C>T
MANE Select: NM_001852
dbSNP: rs372936826
Type: single nucleotide variant
Location: chr1:40314223 (GRCh38)
Gene constraint: LOEUF 0.817 · pLI <0.01 · ClinGen HI 0/3 (gnomAD)
Structure: AlphaFold pLDDT 54.99 · 4 PDB
Residue 77: the 'disordered' region; the 'triple-helical region 4 (col4)' region

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

Similar variants

COL9A2 p.Asp77Glu Uncertain significance ★★ ⚠ same residue
COL9A2 p.Asp77Ala Conflicting classifications of pathogenicity ★ ⚠ 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

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-asp77 (accessed [today's date]).

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