rs199862937

Positions:

chr8-118110925-C-T

Variant summary

Our verdict is Likely benign. Variant got -6 ACMG points: 0P and 6B. BP4_ModerateBS2

The NM_000127.3(EXT1):c.122G>A(p.Ser41Asn) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000156 in 1,614,018 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Synonymous variant affecting the same amino acid position (i.e. S41S) has been classified as Likely benign.

Frequency

Genomes: 𝑓 0.000092 ( 0 hom., cov: 32)

Exomes 𝑓: 0.00016 ( 0 hom. )

Consequence

EXT1
NM_000127.3 missense

Scores

Clinical Significance

Uncertain significance criteria provided, single submitter U:2O:1

Conservation

PhyloP100: 2.50

Variant links:

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]

EXT1 links:

Genome browser will be placed here

ACMG classification

Classification made for transcript

Verdict is Likely_benign. Variant got -6 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.074326485).

BS2

High AC in GnomAd4 at 14 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
EXT1	NM_000127.3 linkuse as main transcript	c.122G>A	p.Ser41Asn	missense_variant	1/11	ENST00000378204.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
EXT1	ENST00000378204.7 linkuse as main transcript	c.122G>A	p.Ser41Asn	missense_variant	1/11	1	NM_000127.3	P1
EXT1	ENST00000437196.1 linkuse as main transcript	c.73+49G>A		intron_variant, NMD_transcript_variant		5

Frequencies

GnomAD3 genomes

AF:

0.0000920

AC:

AN:

152178

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000483

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.000262

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.000207

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.000103

Gnomad OTH

AF:

0.00

GnomAD3 exomes

AF:

0.000108

AC:

AN:

251054

Hom.:

AF XY:

0.000147

AC XY:

AN XY:

135742

show subpopulations

Gnomad AFR exome

AF:

0.0000617

Gnomad AMR exome

AF:

0.000116

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad SAS exome

AF:

0.000294

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.000114

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.000162

AC:

237

AN:

1461722

Hom.:

Cov.:

AF XY:

0.000182

AC XY:

132

AN XY:

727174

show subpopulations

Gnomad4 AFR exome

AF:

0.00

Gnomad4 AMR exome

AF:

0.000201

Gnomad4 ASJ exome

AF:

0.00

Gnomad4 EAS exome

AF:

0.00

Gnomad4 SAS exome

AF:

0.000348

Gnomad4 FIN exome

AF:

0.00

Gnomad4 NFE exome

AF:

0.000171

Gnomad4 OTH exome

AF:

0.000132

GnomAD4 genome

AF:

0.0000919

AC:

AN:

152296

Hom.:

Cov.:

AF XY:

0.000107

AC XY:

AN XY:

74470

show subpopulations

Gnomad4 AFR

AF:

0.0000481

Gnomad4 AMR

AF:

0.000261

Gnomad4 ASJ

AF:

0.00

Gnomad4 EAS

AF:

0.00

Gnomad4 SAS

AF:

0.000207

Gnomad4 FIN

AF:

0.00

Gnomad4 NFE

AF:

0.000103

Gnomad4 OTH

AF:

0.00

Alfa

AF:

0.000134

Hom.:

Bravo

AF:

0.0000680

TwinsUK

AF:

0.000270

AC:

ALSPAC

AF:

0.000519

AC:

ExAC

AF:

0.0000988

AC:

EpiCase

AF:

0.000109

EpiControl

AF:

0.000119

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:2Other:1

Revision: criteria provided, single submitter

LINK: link

Submissions by phenotype

Multiple congenital exostosis

Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Invitae

Aug 23, 2023

This sequence change replaces serine, which is neutral and polar, with asparagine, which is neutral and polar, at codon 41 of the EXT1 protein (p.Ser41Asn). The frequency data for this variant in the population databases is considered unreliable, as metrics indicate poor data quality at this position in the gnomAD database. This missense change has been observed in individual(s) with multiple osteochondromas (PMID: 18373409). ClinVar contains an entry for this variant (Variation ID: 134197). Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) has been performed at Invitae for this missense variant, however the output from this modeling did not meet the statistical confidence thresholds required to predict the impact of this variant on EXT1 protein function. In summary, the available evidence is currently insufficient to determine the role of this variant in disease. Therefore, it has been classified as a Variant of Uncertain Significance. -

not provided

Uncertain:1

Uncertain significance, no assertion criteria provided

clinical testing

Department of Pathology and Laboratory Medicine, Sinai Health System

The EXT1 p.S41N variant was identified in an individual with multiple osteochondromas; however, this variant did not cosegregate with disease in 4 affected family members (Leube_2008_PMID: 18373409). The variant was not identified in COSMIC, but it was identified in dbSNP (ID: rs199862937) and ClinVar (classified as uncertain significance by Invitae). The variant was identified in control databases in 28 of 282452 chromosomes at a frequency of 0.00009913 (Genome Aggregation Database March 6, 2019, v2.1.1). The p.S41 residue is conserved in mammals and computational analyses (MUT Assesor, PolyPhen-2, SIFT, MutationTaster, Revel, FATHMM, MetaLR, DANN) provide inconsistent predictions regarding the impact to the protein; this information is not very predictive of pathogenicity. The variant occurs outside of the splicing consensus sequence and in silico or computational prediction software programs (Splice AI exome) do not predict a deleterious effect on splicing. In summary, based on the above information the clinical significance of this variant cannot be determined with certainty at this time. This variant is classified as a variant of uncertain significance. -

not specified

Other:1

not provided, no classification provided

reference population

ITMI

Sep 19, 2013

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.083

BayesDel_addAF

Benign

-0.19

BayesDel_noAF

Benign

-0.22

CADD

Benign

DANN

Uncertain

0.99

DEOGEN2

Benign

0.37

Eigen

Benign

-0.34

Eigen_PC

Benign

-0.14

FATHMM_MKL

Benign

0.74

LIST_S2

Benign

0.68

M_CAP

Benign

0.056

MetaRNN

Benign

0.074

MetaSVM

Uncertain

0.0061

MutationAssessor

Benign

-0.69

MutationTaster

Benign

0.99

PrimateAI

Uncertain

0.62

PROVEAN

Benign

-0.53

REVEL

Uncertain

0.30

Sift

Benign

0.13

Sift4G

Benign

0.32

Polyphen

0.012

Vest4

0.26

MVP

0.71

MPC

0.37

ClinPred

0.026

GERP RS

4.2

Varity_R

0.12

gMVP

0.55

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.010

Details are displayed if max score is > 0.2

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

Publications

LitVar

Below is the list of publications found by LitVar. It may be empty.

Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

LitVar

Other links and lift over