Is EXT2 p.Ala681Pro (c.2041G>C) pathogenic?

EXT2 p.Ala681Pro (c.2041G>C) is classified Uncertain significance in EXT2 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-04-08). AlphaMissense: likely pathogenic (0.9938); Very rare (popmax 0.00237%, nfe); Associated with exostoses, multiple, type 2.

What condition is associated with EXT2 p.Ala681Pro (c.2041G>C)?

EXT2 p.Ala681Pro (c.2041G>C) is associated with exostoses, multiple, type 2 (ClinVar).

How common is EXT2 p.Ala681Pro (c.2041G>C) in the general population?

EXT2 p.Ala681Pro (c.2041G>C) is very rare (popmax 0.00237%, nfe) (gnomAD).

How is Multiple osteochondromas inherited?

Typically Autosomal dominant (Orphanet). A genetic counselor can assess individual risk for a family.

What do computational predictors say about EXT2 p.Ala681Pro (c.2041G>C)?

AlphaMissense predicts likely pathogenic (score 0.9938) — an in-silico prediction, not a clinical call.

EXT2 p.Ala681Pro

c.2041G>C · rs771936445 · VCV1491326

Uncertain significance Single submitter

Classification

Uncertain significance

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

AlphaMissense

likely pathogenic

0.9938 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00237%, nfe)

Missense predictors

3/3 damaging

AlphaMissense, REVEL, SaProt

Conditions

exostoses, multiple, type 2

Computational evidence

Protein change
AlphaMissense	0.9938	likely pathogenic · top 10% in EXT2
REVEL	0.725	pathogenic-leaning
SaProt	LLR -16.06	damaging
⇒ AlphaMissense, REVEL and SaProt all call this damaging.
Splicing
SpliceAI	<0.2	no splice effect predicted · four deltas, not one · how we know
Constraint at this position
Conservation	phyloP 12	GERP 1.9, phastCons 1
Regional constraint	o/e 0.62	unconstrained · MANE · 37 kb · p 3.2e-09 · regional, not allelic
Overall
CADD	33.0	PHRED · no single calibrated threshold — expert panels disagree

ClinVar classifies this uncertain; the computational predictors unanimously lean damaging — 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 0.00237% European (non-Finnish) · 28/1,179,988 alleles

Filtering AF 0.00164% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00142%

Overall 0.00173% 28/1,614,068 alleles · very rare exomes 28/1,461,832 · genomes 0/152,236 · joint denominator

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: EXT2
Protein: p.Ala681Pro
Coding: c.2041G>C
MANE Select: NM_207122
dbSNP: rs771936445
Type: single nucleotide variant
Location: chr11:44244171 (GRCh38)
Gene constraint: LOEUF 0.775 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 87.59 · 6 PDB
Residue 681: an α-helix

Full EXT2 gene report on Sugi Atlas → Gene function, pathways, protein structure, interactions & more

Disease context

exostoses, multiple, type 2 — disease report on Sugi Atlas → Associated genes, phenotypes, clinical trials & treatments

For Multiple osteochondromas (Orphanet):

Inheritance: Autosomal dominant
Onset: Childhood
Prevalence: >1 / 1000 (Specific population)

Similar variants

EXT2 c.1079+1G>A Pathogenic ★★ same condition
EXT2 c.1079+1G>T Pathogenic ★★ same condition
EXT2 c.1173+1G>A Pathogenic ★★ same condition
EXT2 c.1662+1G>C Likely pathogenic ★★ same condition
EXT2 c.536+1G>A Pathogenic ★★ same condition
EXT2 c.626+1G>A Pathogenic ★★ same condition
EXT2 c.626+1G>C Pathogenic ★★ same condition
EXT2 c.626+1G>T Pathogenic/Likely pathogenic ★★ same condition

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/ext2-p-ala681pro (accessed [today's date]).

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