Is EXT2 p.Tyr348Cys (c.1043A>G) pathogenic?

EXT2 p.Tyr348Cys (c.1043A>G) is classified Uncertain significance in EXT2 (ClinVar, Multiple submitters, 3 submitters; last evaluated 2025-01-22). AlphaMissense: ambiguous (0.3665); Very rare (popmax 0.00534%, afr); Associated with exostoses, multiple, type 2.

What condition is associated with EXT2 p.Tyr348Cys (c.1043A>G)?

EXT2 p.Tyr348Cys (c.1043A>G) is associated with exostoses, multiple, type 2 (ClinVar).

How common is EXT2 p.Tyr348Cys (c.1043A>G) in the general population?

EXT2 p.Tyr348Cys (c.1043A>G) is very rare (popmax 0.00534%, afr) (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.Tyr348Cys (c.1043A>G)?

AlphaMissense predicts ambiguous (score 0.3665) — an in-silico prediction, not a clinical call.

EXT2 p.Tyr348Cys

c.1043A>G · rs758785296 · VCV1439910

Uncertain significance Multiple submitters

Classification

Uncertain significance

ClinVar

Review

Multiple submitters ★★☆☆

ClinVar · 3 submitters

AlphaMissense

ambiguous

0.3665 · ACMG-weighted

gnomAD v4.1

Rare

very rare (popmax 0.00534%, afr)

Missense predictors

2/2 damaging

REVEL, SaProt · AlphaMissense no call

Conditions

exostoses, multiple, type 2

Computational evidence

Protein change
AlphaMissense	0.3665	ambiguous
REVEL	0.962	strongly pathogenic-leaning
SaProt	LLR -11.29	damaging
⇒ REVEL and SaProt both call this damaging; AlphaMissense makes no call.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 11	GERP 2.5, 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 0.00534% African / African-American · 4/74,878 alleles

Filtering AF 0.00175% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00104%

Overall 0.00136% 22/1,613,986 alleles · very rare exomes 19/1,461,890 · genomes 3/152,096 · joint denominator

Ancestry group	Frequency	1 in
African / African-Americangrpmax	0.00534%	18,720
European (non-Finnish)	0.00153%	65,557

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.Tyr348Cys
Coding: c.1043A>G
MANE Select: NM_207122
dbSNP: rs758785296
Type: single nucleotide variant
Location: chr11:44126919 (GRCh38)
Gene constraint: LOEUF 0.775 · pLI <0.01 · ClinGen HI 3/3 (gnomAD)
Structure: AlphaFold pLDDT 87.59 · 6 PDB

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.Tyr348Ter Pathogenic/Likely pathogenic ★★ same residue
EXT2 p.Tyr348Asp Uncertain significance ★ ⚠ same residue
EXT2 p.Tyr348= Likely benign ★ 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-tyr348cys (accessed [today's date]).

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