chr8-117835543-G-T

Variant names:

• chr8-117835543-G-T
• rs11546829
• NM_000127.3:c.1065C>A

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PVS1 PM2 PP5_Moderate

The NM_000127.3(EXT1):​c.1065C>A​(p.Cys355*) variant causes a stop gained change involving the alteration of a non-conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★). Synonymous variant affecting the same amino acid position (i.e. C355C) has been classified as Benign. Variant results in nonsense mediated mRNA decay.

• Frequency: Genomes: not found (cov: 32)
• Consequence: EXT1 NM_000127.3 stop_gained
• Clinical Significance: Pathogenic criteria provided, single submitter P:1
• Conservation: PhyloP100: -0.00900
• Publications: 23 publications found

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

ACMG classification

Our verdict: Pathogenic. The variant received 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 8-117835543-G-T is Pathogenic according to our data. Variant chr8-117835543-G-T is described in ClinVar as Pathogenic. ClinVar VariationId is 570990.Status of the report is criteria_provided_single_submitter, 1 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
EXT1	NM_000127.3	c.1065C>A	p.Cys355*	stop_gained	Exon 3 of 11	ENST00000378204.7	NP_000118.2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
EXT1	ENST00000378204.7	c.1065C>A	p.Cys355*	stop_gained	Exon 3 of 11	1	NM_000127.3	ENSP00000367446.3
EXT1	ENST00000436216.2	n.432C>A		non_coding_transcript_exon_variant	Exon 3 of 6	3		ENSP00000400372.1
EXT1	ENST00000437196.1	n.82C>A		non_coding_transcript_exon_variant	Exon 2 of 10	5		ENSP00000407299.1
EXT1	ENST00000684189.1	n.532C>A		non_coding_transcript_exon_variant	Exon 3 of 11

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 33

GnomAD4 genome Cov.: 32

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:1

Revision: criteria provided, single submitter

Submissions by phenotype

Multiple congenital exostosis Pathogenic:1

Apr 14, 2018

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This variant has not been reported in the literature in individuals with EXT1-related disease. For these reasons, this variant has been classified as Pathogenic. Loss-of-function variants in EXT1 are known to be pathogenic (PMID: 10679937, 11391482, 19810120). This variant is not present in population databases (ExAC no frequency). This sequence change creates a premature translational stop signal (p.Cys355*) in the EXT1 gene. It is expected to result in an absent or disrupted protein product. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.17
BayesDel_addAF	Pathogenic	0.63	D
BayesDel_noAF	Pathogenic	0.58
CADD	Pathogenic	36
DANN	Uncertain	0.99
Eigen	Uncertain	0.52
Eigen_PC	Uncertain	0.32
FATHMM_MKL	Uncertain	0.81	D
PhyloP100		-0.0090
Vest4		0.99
ClinPred		0.96	D
GERP RS		1.4
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Mutation Taster		=0/200	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.070		Details are displayed if max score is > 0.2

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

Other links and lift over

dbSNP: rs11546829; hg19: chr8-118847782;