Is EXT2 p.Arg80Trp (c.238C>T) pathogenic?

EXT2 p.Arg80Trp (c.238C>T) is classified Conflicting classifications of pathogenicity in EXT2 (ClinVar, Conflicting submitters, 2 submitters; last evaluated 2026-01-21). AlphaMissense: ambiguous (0.4493); Very rare (popmax 0.00891%, eas); Associated with exostoses, multiple, type 2.

What condition is associated with EXT2 p.Arg80Trp (c.238C>T)?

EXT2 p.Arg80Trp (c.238C>T) is associated with exostoses, multiple, type 2 (ClinVar).

How common is EXT2 p.Arg80Trp (c.238C>T) in the general population?

EXT2 p.Arg80Trp (c.238C>T) is very rare (popmax 0.00891%, eas) (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.Arg80Trp (c.238C>T)?

AlphaMissense predicts ambiguous (score 0.4493) — an in-silico prediction, not a clinical call.

EXT2 p.Arg80Trp

c.238C>T · rs755625888 · VCV1008439

Conflicting classifications of pathogenicity Conflicting submitters

Classification

Conflicting classifications of pathogenicity

ClinVar

Review

Conflicting submitters ★☆☆☆

ClinVar · 2 submitters

AlphaMissense

ambiguous

0.4493 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00891%, eas)

Conditions

exostoses, multiple, type 2

Computational evidence

Protein change
AlphaMissense	0.4493	ambiguous
REVEL	0.599	indeterminate
SaProt	LLR -9.96	tolerated
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 3.3	GERP 2.3, phastCons 1
Regional constraint	o/e 0.93	unconstrained · MANE · 99 kb · p 0.085 · regional, not allelic
Overall
CADD	28.1	PHRED · no single calibrated threshold — expert panels disagree

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

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.00891% East Asian · 4/44,888 alleles

Filtering AF 0.00511% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00468%

Overall 0.00539% 87/1,614,064 alleles · very rare exomes 85/1,461,886 · genomes 2/152,178 · joint denominator

Ancestry group	Frequency	1 in
East Asiangrpmax	0.00891%	11,222
Admixed American	0.00667%	15,001
Remaining individualsnot grpmax-eligible	0.0064%	15,622
European (non-Finnish)	0.00627%	15,947
African / African-American	0.00133%	74,922

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.Arg80Trp
Coding: c.238C>T
MANE Select: NM_207122
dbSNP: rs755625888
Type: single nucleotide variant
Location: chr11:44107950 (GRCh38)
Gene constraint: LOEUF 0.775 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 87.59 · 6 PDB
Residue 80: 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 p.Arg80Gln Uncertain significance ★★ ⚠ same residue
EXT2 p.Arg80Pro Uncertain significance ★★ ⚠ same residue
EXT2 p.Arg80fs Likely pathogenic ★ same residue
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

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-arg80trp (accessed [today's date]).

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