EXT1

Chr 8

exostosin glycosyltransferase 1

Also known as: EXT, LGCR, LGS, TRPS2, TTV

NCBI Gene: 2131ENSG00000182197UniProt: Q16394

This gene encodes an endoplasmic reticulum-resident type II transmembrane glycosyltransferase involved in the chain elongation step of heparan sulfate biosynthesis. Mutations in this gene cause the type I form of multiple exostoses. [provided by RefSeq, Jul 2008]

GeneReviewsResearchGenerating clinical summary…

Primary Disease Associations & Inheritance

UniProtHereditary multiple exostoses 1
UniProtChondrosarcoma

Clinical highlights

Gene-disease validity (ClinGen)
exostoses, multiple, type 1 · ADDefinitivesufficient evidence for diagnostic panels
Interpreting a novel variant
Loss of function is the curated mechanism (Gene2Phenotype) and the gene is intolerant of it in the population — truncating, frameshift and canonical splice variants carry more prior weight here than missense.Curated gene-level mechanism — a prior for triage, not a per-variant call.
2
Active trials
73
Pubs (1 yr)
—
P/LP submissions
—
P/LP missense
0.26
LOEUF· LoF intol.
LOF
Mechanism· G2P
📖
GeneReview available — EXT1
Authoritative clinical overview · Recommended first read
Open GeneReview ↗
Some data sources returned errors (1)

omim: Error: OMIM fetch failed: 429

Population Genetics & Constraint

gnomAD v4 — loss-of-function & missense intolerance

gnomAD
LoF intolerant — likely haploinsufficient
LoF Constraint?
0.26LOEUF
pLI 0.997
Z-score 4.86
OE 0.11 (0.06–0.26)
Highly constrained

Highly LoF-intolerant (top ~10% of genes)

Missense Constraint?
1.67Z-score
OE missense 0.77 (0.70–0.84)
317 obs / 412.2 exp
Tolerant

Mild missense constraint

Observed / Expected Ratios?
LoF OE?0.11 (0.06–0.26)
0≤0.351.4
Missense OE?0.77 (0.70–0.84)
0≤0.61.4
Synonymous OE?1.07
0≤1.21.6
LoF obs/exp: 4 / 35.0Missense obs/exp: 317 / 412.2Syn Z: -0.73

ClinVar Variant Classifications

0 submitted variants in ClinVar

ClinVar

Protein Context — Lollipop Plot

EXT1 · protein map & ClinVar variants

Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.

External Resources

Links to major genomics databases and tools

Franklin by Genoox
AI-powered variant curation and clinical analysis
DECIPHER
Genomic variants and phenotypes in rare disease patients