• 3
    Haplo
    Score
  • 0
    Triplo
    Score

Gene Facts External Data Attribution

HGNC Symbol
EXT1 (HGNC:3512) HGNC Entrez Ensembl OMIM UCSC Uniprot GeneReviews LOVD LSDB ClinVar
HGNC Name
exostosin glycosyltransferase 1
Gene type
protein-coding gene
Locus type
gene with protein product
Previous symbols
LGCR, LGS
Alias symbols
ttv
%HI
1.49(Read more about the DECIPHER Haploinsufficiency Index)
pLI
1(Read more about gnomAD pLI score)
LOEUF
0.26(Read more about gnomAD LOEUF score)
Cytoband
8q24.11
Genomic Coordinates
GRCh37/hg19: chr8:118806729-119124065 NCBI Ensembl UCSC
GRCh38/hg38: chr8:117794490-118111826 NCBI Ensembl UCSC
MANE Select Transcript
NM_000127.3 ENST00000378204.7 (Read more about MANE Select)
Function
Glycosyltransferase forming with EXT2 the heterodimeric heparan sulfate polymerase which catalyzes the elongation of the heparan sulfate glycan backbone (PubMed:9620772, PubMed:10639137, PubMed:22660413, PubMed:36402845, PubMed:36593275). Glycan backbone extension consists in the alternating transfer of (1->4)-beta-D-GlcA and (1->4)-alpha-D-GlcNAc residues from their respective UDP-sugar donors. Both EXT1 and EXT2 are required for the full activity of the polymerase since EXT1 bears the N-acetyl... (Source: Uniprot)

Dosage Sensitivity Summary (Gene)

Dosage ID:
ISCA-9321
Curation Status:
Complete
Issue Type:
Dosage Curation - Gene
Haploinsufficiency:
Sufficient Evidence for Haploinsufficiency (3)
Triplosensitivity:
No Evidence for Triplosensitivity (0)
Last Evaluated:
06/17/2020

Haploinsufficiency (HI) Score Details

HI Score:
3
HI Evidence Strength:
Sufficient Evidence for Haploinsufficiency (Disclaimer)
HI Disease:
HI Evidence:
  • PUBMED: 29529714
    In 2018, Santos et al. used Sanger sequencing and Multiplex ligation-dependent probe amplification (MLPA) on 153 Brazilian patients in 114 families with multiple osteochondromas (MO) to identify variants in EXT1 and EXT2. The authors identified variants in EXT1 in 42 of the 114 unrelated individuals with MO. 33 of these variants were unique. Of these, 13 were frameshifts, 5 were missense variants, 11 were nonsense, 2 were splice site variants, and 2 were large deletions.
  • PUBMED: 30334991
    In 2018, Li et al. used Sanger sequencing and Multiplex ligation-dependent probe amplification (MLPA) on unrelated individuals from 73 Chinese families with hereditary multiple osteochondroma (HMO) to identify variants in EXT1 and EXT2. Analysis identified 33 unique variants in EXT1 in 39 families. Of these, 16 were frameshifts, 3 were nonsense variants, 5 were splice site variants, 4 were large deletions, and 1 was an in-frame deletion.
  • PUBMED: 28690282
    In 2017, Guo et al. used targeted next-generation sequencing (t-NGS) and Sanger sequencing on 10 patients with multiple osteochondromas (MO) to identify potential variants in EXT1 and EXT2. The authors identified 5 variants in EXT1, 3 of which were nonsense variants.
HI Evidence Comments:
Please see GeneReviews for a detailed discussion of the evidence supporting haploinsufficiency for EXT1. Per GeneReviews, "Osteochondromas were previously called exostoses; however, the term exostosis is no longer used to describe the lesions in HMO because the term osteochondroma specifies that these lesions are cartilaginous processes that ossify and not simply outgrowths of bone. The changed terminology has been adopted by the World Health Organization (WHO)."

Triplosensitivity (TS) Score Details

TS Score:
0
TS Evidence Strength:
No Evidence for Triplosensitivity (Disclaimer)

Genomic View

Select assembly: (NC_000008.10) (NC_000008.11)