chr8-117822522-C-T

Variant names:

Variant summary

Our verdict is Benign. The variant received -18 ACMG points: 0P and 18B. BP4_ModerateBP6_Very_StrongBS1BS2

The NM_000127.3(EXT1):c.1360G>A(p.Val454Ile) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000403 in 1,613,266 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a benign outcome for this variant. 13/22 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

Frequency

Genomes: 𝑓 0.000039 ( 0 hom., cov: 32)

Exomes 𝑓: 0.000040 ( 0 hom. )

Consequence

EXT1
NM_000127.3 missense

Scores

Clinical Significance

Likely benign criteria provided, multiple submitters, no conflicts B:5O:1

Conservation

PhyloP100: 3.03

Publications

4 publications found

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 Gene-Disease associations (from GenCC):

exostoses, multiple, type 1
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), G2P, ClinGen
chondrosarcoma
Inheritance: AD Classification: STRONG Submitted by: Genomics England PanelApp
hereditary multiple osteochondromas
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

EXT1 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Benign. The variant received -18 ACMG points.

BP4

Computational evidence support a benign effect (MetaRNN=0.14618215).

BP6

Variant 8-117822522-C-T is Benign according to our data. Variant chr8-117822522-C-T is described in ClinVar as Likely_benign. ClinVar VariationId is 134200.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

BS1

Variant frequency is greater than expected in population mid. GnomAdExome4 allele frequency = 0.0000404 (59/1460996) while in subpopulation MID AF = 0.000694 (4/5762). AF 95% confidence interval is 0.000236. There are 0 homozygotes in GnomAdExome4. There are 23 alleles in the male GnomAdExome4 subpopulation. Median coverage is 31. This position passed quality control check.

BS2

High AC in GnomAd4 at 6 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
EXT1	NM_000127.3 link	c.1360G>A	p.Val454Ile	missense_variant	Exon 5 of 11	ENST00000378204.7	NP_000118.2	Q16394

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
EXT1	ENST00000378204.7 link	c.1360G>A	p.Val454Ile	missense_variant	Exon 5 of 11	1	NM_000127.3	ENSP00000367446.3		Q16394

Frequencies

GnomAD3 genomes

AF:

0.0000394

AC:

AN:

152152

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000965

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

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:

0.0000147

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.0000399

AC:

AN:

250834

AF XY:

0.0000590

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

Gnomad ASJ exome

AF:

0.00

Gnomad EAS exome

AF:

0.00

Gnomad FIN exome

AF:

0.00

Gnomad NFE exome

AF:

0.0000529

Gnomad OTH exome

AF:

0.00

GnomAD4 exome

AF:

0.0000404

AC:

AN:

1460996

Hom.:

Cov.:

AF XY:

0.0000316

AC XY:

AN XY:

726838

show subpopulations

African (AFR)

AF:

0.000389

AC:

AN:

33460

American (AMR)

AF:

0.0000447

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26126

East Asian (EAS)

AF:

0.0000504

AC:

AN:

39664

South Asian (SAS)

AF:

0.0000348

AC:

AN:

86250

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53088

Middle Eastern (MID)

AF:

0.000694

AC:

AN:

5762

European-Non Finnish (NFE)

AF:

0.0000279

AC:

AN:

1111558

Other (OTH)

AF:

0.0000663

AC:

AN:

60364

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.484

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Exome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

GnomAD4 genome

AF:

0.0000394

AC:

AN:

152270

Hom.:

Cov.:

AF XY:

0.0000537

AC XY:

AN XY:

74460

show subpopulations

African (AFR)

AF:

0.0000962

AC:

AN:

41568

American (AMR)

AF:

0.00

AC:

AN:

15300

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3468

East Asian (EAS)

AF:

0.00

AC:

AN:

5184

South Asian (SAS)

AF:

0.000207

AC:

AN:

4826

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10604

Middle Eastern (MID)

AF:

0.00

AC:

AN:

294

European-Non Finnish (NFE)

AF:

0.0000147

AC:

AN:

67998

Other (OTH)

AF:

0.00

AC:

AN:

2116

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.508

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Alfa

AF:

0.000135

Hom.:

Bravo

AF:

0.0000378

ExAC

AF:

0.0000330

AC:

Asia WGS

AF:

0.000289

AC:

AN:

3478

EpiCase

AF:

0.000109

EpiControl

AF:

0.0000593

ClinVar

Significance: Likely benign

Submissions summary: Benign:5Other:1

Revision: criteria provided, multiple submitters, no conflicts

LINK: link

Submissions by phenotype

Multiple congenital exostosis

Benign:2

Nov 05, 2024

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Apr 27, 2017

Illumina Laboratory Services, Illumina

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. The evidence from the literature, in combination with allele frequency data from public databases where available, was sufficient to determine this variant is unlikely to cause disease. Therefore, this variant is classified as likely benign. -

Langer-Giedion syndrome

Benign:1

Jun 14, 2016

Illumina Laboratory Services, Illumina

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not provided

Benign:1

Department of Pathology and Laboratory Medicine, Sinai Health System

Significance:Likely benign

Review Status:no assertion criteria provided

Collection Method:clinical testing

The EXT1 p.V454I variant was identified in an individual with multiple osteochondromas, as well as in a cohort of healthy individuals (Signori_2007_PMID: 17301954; Bodian_2014_PMID: 24728327). The variant was identified in dbSNP (ID: rs201504622), ClinVar (classified as likely benign by Illumina), and COSMIC (tissue: biliary tract). The variant was identified in control databases in 12 of 282230 chromosomes at a frequency of 0.00004252 (Genome Aggregation Database March 6, 2019, v2.1.1). The p.V454 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 although we would lean towards a more benign role for this variant. This variant is classified as likely benign. -

Exostoses, multiple, type 1

Benign:1

Jul 07, 2023

KCCC/NGS Laboratory, Kuwait Cancer Control Center

Significance:Likely benign

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

not specified

Other:1

Sep 19, 2013

ITMI

Significance:not provided

Review Status:no classification provided

Collection Method:reference population

- -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

AlphaMissense

Benign

0.079

BayesDel_addAF

Benign

-0.036

BayesDel_noAF

Benign

-0.090

CADD

Benign

(source)

DANN

Uncertain

0.99

DEOGEN2

Benign

0.35

Eigen

Benign

-0.097

Eigen_PC

Benign

0.15

FATHMM_MKL

Uncertain

0.91

LIST_S2

Uncertain

0.86

M_CAP

Benign

0.030

MetaRNN

Benign

0.15

MetaSVM

Uncertain

0.13

MutationAssessor

Benign

0.63

PhyloP100

3.0

PrimateAI

Uncertain

0.55

PROVEAN

Benign

-0.46

REVEL

Uncertain

0.32

Sift

Benign

0.62

Sift4G

Benign

0.58

Polyphen

0.0070

Vest4

0.24

MVP

0.50

MPC

0.35

ClinPred

0.072

GERP RS

6.1

Varity_R

0.091

gMVP

0.52

Mutation Taster

=83/17

polymorphism

(source)

Splicing

Name

Calibrated prediction

Score

Prediction

SpliceAI score (max)

0.0

Details are displayed if max score is > 0.2

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

Publications

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over