Is EXT2 p.Ser591= (c.1773C>T) pathogenic?

EXT2 p.Ser591= (c.1773C>T) is classified Likely benign in EXT2 (ClinVar, Single submitter, 1 submitter; last evaluated 2025-11-01). Ultra-rare (popmax 0.0183%, amr); Associated with exostoses, multiple, type 2.

What condition is associated with EXT2 p.Ser591= (c.1773C>T)?

EXT2 p.Ser591= (c.1773C>T) is associated with exostoses, multiple, type 2 (ClinVar).

How common is EXT2 p.Ser591= (c.1773C>T) in the general population?

EXT2 p.Ser591= (c.1773C>T) is ultra-rare (popmax 0.0183%, amr) (gnomAD).

How is Multiple osteochondromas inherited?

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

EXT2 p.Ser591=

c.1773C>T · rs779667149 · VCV2198944

Likely benign Single submitter

Classification

Likely benign

ClinVar

Review

Single submitter ★☆☆☆

ClinVar · 1 submitter

gnomAD v4.1

Rare

ultra-rare (popmax 0.0183%, amr)

Conditions

exostoses, multiple, type 2

Computational evidence

Protein change
Missense predictors do not apply to this variant type; conservation carries the signal.
Splicing
SpliceAI	—	not assessed · no allele here is in the release
Constraint at this position
Conservation	phyloP 1.7	GERP 1.3, phastCons 1
Overall
CADD	12.53	PHRED · no single calibrated threshold — expert panels disagree

Population frequency

gnomAD v4.1 · exomes + genomes

Grpmax group 0.0183% Admixed American · 11/59,978 alleles

Filtering AF 0.0102% ClinGen BA1/BS1 input FAF95, joint · FAF99 0.00786%

Overall 0.000806% 13/1,613,854 alleles · ultra-rare exomes 11/1,461,734 · genomes 2/152,120 · joint denominator

Ancestry group	Frequency	1 in
Admixed Americangrpmax	0.0183%	5,453
European (non-Finnish)	0.000169%	589,974

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.Ser591=
Coding: c.1773C>T
MANE Select: NM_207122
dbSNP: rs779667149
Type: single nucleotide variant
Location: chr11:44232463 (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.Ser591Pro Uncertain significance ★★ ⚠ 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
EXT2 c.626+1G>A Pathogenic ★★ same condition
EXT2 c.626+1G>C 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-ser591 (accessed [today's date]).

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