8-117819782-G-A

Position:

• chr8-117819782-G-A

Variant summary

Our verdict is Uncertain significance. Variant got 0 ACMG points: 2P and 2B. PM2 BP4_Moderate

The NM_000127.3(EXT1):​c.1430C>T​(p.Pro477Leu) variant causes a missense 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. 13/21 in silico tools predict a benign outcome for this variant. Variant has been reported in ClinVar as Uncertain significance (★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P477A) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 32)
• Consequence: EXT1 NM_000127.3 missense
• Clinical Significance: Uncertain significance criteria provided, single submitter U:1
• Conservation: PhyloP100: 2.23

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 Uncertain_significance. Variant got 0 ACMG points.

• PM2: Very rare variant in population databases, with high coverage
• BP4: Computational evidence support a benign effect (MetaRNN=0.1705743).

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
EXT1	NM_000127.3	c.1430C>T	p.Pro477Leu	missense_variant	6/11	ENST00000378204.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
EXT1	ENST00000378204.7	c.1430C>T	p.Pro477Leu	missense_variant	6/11	1	NM_000127.3	P1
EXT1	ENST00000684189.1	n.897C>T		non_coding_transcript_exon_variant	6/11
EXT1	ENST00000437196.1	c.*321C>T		3_prime_UTR_variant, NMD_transcript_variant	5/10	5

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 32

ClinVar

Significance: Uncertain significance

Submissions summary: Uncertain:1

Revision: criteria provided, single submitter

Submissions by phenotype

Multiple congenital exostosis Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Aug 25, 2023

This sequence change replaces proline, which is neutral and non-polar, with leucine, which is neutral and non-polar, at codon 477 of the EXT1 protein (p.Pro477Leu). This variant is not present in population databases (gnomAD no frequency). This variant has not been reported in the literature in individuals affected with EXT1-related conditions. 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) performed at Invitae indicates that this missense variant is not expected to disrupt 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. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.076
BayesDel_addAF	Uncertain	0.090	D
BayesDel_noAF	Benign	-0.11
CADD	Benign	22
DANN	Benign	0.64
DEOGEN2	Uncertain	0.44	T
Eigen	Benign	-0.085
Eigen_PC	Benign	0.15
FATHMM_MKL	Uncertain	0.90	D
LIST_S2	Uncertain	0.87	D
M_CAP	Benign	0.028	D
MetaRNN	Benign	0.17	T
MetaSVM	Uncertain	0.11	D
MutationAssessor	Benign	1.3	L
MutationTaster	Benign	1.0	D
PrimateAI	Uncertain	0.63	T
PROVEAN	Benign	-1.8	N
REVEL	Uncertain	0.32
Sift	Benign	0.78	T
Sift4G	Benign	0.82	T
Polyphen		0.0	B
Vest4		0.089
MutPred		0.41		Loss of catalytic residue at P476 (P = 0.0171);
MVP		0.67
MPC		0.40
ClinPred		0.83	D
GERP RS		5.9
Varity_R		0.11
gMVP		0.66

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

No publications associated with this variant yet.

Other links and lift over

hg19: chr8-118832021;