chr8-118110383-TGATGCTGGCTTTG-T

Position:

• chr8-118110383-TGATGCTGGCTTTG-T

Variant summary

Our verdict is Pathogenic. Variant got 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000127.3(EXT1):​c.651_663del​(p.Lys218ValfsTer30) variant causes a frameshift change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. Variant has been reported in ClinVar as Pathogenic (★). Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: EXT1 NM_000127.3 frameshift
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: 9.91

Genes affected

EXT1 (HGNC:3512): (exostosin glycosyltransferase 1) 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]

ACMG classification

Verdict is Pathogenic. Variant got 12 ACMG points.

• PVS1: Loss of function variant, product undergoes nonsense mediated mRNA decay. LoF is a known mechanism of disease.
• PM2: Very rare variant in population databases, with high coverage
• PP5: Variant 8-118110383-TGATGCTGGCTTTG-T is Pathogenic according to our data. Variant chr8-118110383-TGATGCTGGCTTTG-T is described in ClinVar as [Pathogenic]. Clinvar id is 526303.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
EXT1	NM_000127.3	c.651_663del	p.Lys218ValfsTer30	frameshift_variant	1/11	ENST00000378204.7	NP_000118.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
EXT1	ENST00000378204.7	c.651_663del	p.Lys218ValfsTer30	frameshift_variant	1/11	1	NM_000127.3	ENSP00000367446	P1
EXT1	ENST00000436216.2	c.19_31del	p.Lys8ValfsTer30	frameshift_variant, NMD_transcript_variant	1/6	3		ENSP00000400372
EXT1	ENST00000437196.1	c.73+578_73+590del		intron_variant, NMD_transcript_variant		5		ENSP00000407299

Frequencies

GnomAD3 genomes Cov.: 32

We have no GnomAD4 exomes data on this position. Probably position not covered by the project.

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Multiple congenital exostosis Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Mar 14, 2022

For these reasons, this variant has been classified as Pathogenic. ClinVar contains an entry for this variant (Variation ID: 526303). This premature translational stop signal has been observed in individual(s) with clinical features of hereditary multiple osteochondromatosis (Invitae). This variant is not present in population databases (gnomAD no frequency). This sequence change creates a premature translational stop signal (p.Lys218Valfs*30) in the EXT1 gene. It is expected to result in an absent or disrupted protein product. Loss-of-function variants in EXT1 are known to be pathogenic (PMID: 10679937, 11391482, 19810120). -

Computational scores

Source: dbNSFP v4.3

Splicing

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Publications

LitVar

Other links and lift over

dbSNP: rs1554601504; hg19: chr8-119122622;