8-117799775-G-A

Variant summary

Our verdict is Benign. Variant got -19 ACMG points: 0P and 19B. BP4_Moderate BP6_Very_Strong BP7 BS1 BS2

The NM_000127.3(EXT1):c.2178C>T(p.Pro726=) variant causes a synonymous change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.000221 in 1,614,148 control chromosomes in the GnomAD database, including 6 homozygotes. In-silico tool predicts a benign outcome for this variant. Variant has been reported in ClinVar as Likely benign (★★).

• Frequency:
  • Genomes: 𝑓 0.00014 (0 hom., cov: 32)
  • Exomes 𝑓: 0.00023 (6 hom.)
• Consequence: EXT1 NM_000127.3 synonymous
• Clinical Significance: Benign/Likely benign criteria provided, multiple submitters, no conflicts B:2
• Conservation: PhyloP100: -0.222

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 Benign. Variant got -19 ACMG points.

• BP4: Computational evidence support a benign effect (BayesDel_noAF=-0.39).
• BP6: Variant 8-117799775-G-A is Benign according to our data. Variant chr8-117799775-G-A is described in ClinVar as [Likely_benign]. Clinvar id is 783178.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.
• BP7: Synonymous conserved (PhyloP=-0.222 with no splicing effect.
• BS1: Variant frequency is greater than expected in population sas. gnomad4 allele frequency = 0.000144 (22/152258) while in subpopulation SAS AF= 0.0029 (14/4820). AF 95% confidence interval is 0.00176. There are 0 homozygotes in gnomad4. There are 18 alleles in male gnomad4 subpopulation. Median coverage is 32. This position pass quality control queck.
• BS2: High AC in GnomAd at 22 AD gene.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
EXT1	NM_000127.3	c.2178C>T	p.Pro726=	synonymous_variant	11/11	ENST00000378204.7

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
EXT1	ENST00000378204.7	c.2178C>T	p.Pro726=	synonymous_variant	11/11	1	NM_000127.3	P1
EXT1	ENST00000684189.1	n.1645C>T		non_coding_transcript_exon_variant	11/11
EXT1	ENST00000684443.1	n.2304C>T		non_coding_transcript_exon_variant	2/2
EXT1	ENST00000437196.1			downstream_gene_variant		5

Frequencies

GnomAD3 genomes AF: 0.000145 AC: 22 AN: 152140 Hom.: 0 Cov.: 32

Gnomad AFR AF: 0.0000965

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.00

Gnomad EAS AF: 0.000193

Gnomad SAS AF: 0.00290

Gnomad FIN AF: 0.00

Gnomad MID AF: 0.00

Gnomad NFE AF: 0.0000441

Gnomad OTH AF: 0.00

GnomAD3 exomes AF: 0.000430 AC: 108 AN: 251346 Hom.: 3 AF XY: 0.000618 AC XY: 84 AN XY: 135828

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.000652

Gnomad SAS exome AF: 0.00300

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.0000176

Gnomad OTH exome AF: 0.000326

GnomAD4 exome AF: 0.000229 AC: 335 AN: 1461890 Hom.: 6 Cov.: 32 AF XY: 0.000348 AC XY: 253 AN XY: 727244

Gnomad4 AFR exome AF: 0.0000299

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.000529

Gnomad4 SAS exome AF: 0.00325

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.0000162

Gnomad4 OTH exome AF: 0.000215

GnomAD4 genome AF: 0.000144 AC: 22 AN: 152258 Hom.: 0 Cov.: 32 AF XY: 0.000242 AC XY: 18 AN XY: 74440

Gnomad4 AFR AF: 0.0000962

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.00

Gnomad4 EAS AF: 0.000193

Gnomad4 SAS AF: 0.00290

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.0000441

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000712 Hom.: 0

Bravo AF: 0.0000642

Asia WGS AF: 0.000577 AC: 2 AN: 3478

EpiCase AF: 0.0000545

EpiControl AF: 0.00

ClinVar

Significance: Benign/Likely benign

Submissions summary: Benign:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

Multiple congenital exostosis Benign:1

Benign, criteria provided, single submitter

clinical testing

Invitae

Dec 08, 2021

- -

EXT1-related disorder Benign:1

Likely benign, criteria provided, single submitter

clinical testing

PreventionGenetics, part of Exact Sciences

Jan 21, 2022

This variant is classified as likely benign based on ACMG/AMP sequence variant interpretation guidelines (Richards et al. 2015 PMID: 25741868, with internal and published modifications). -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
BayesDel_noAF	Benign	-0.39
Cadd	Benign	12
Dann	Benign	0.67

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

LitVar

Other links and lift over

dbSNP: rs557560039; hg19: chr8-118812014; COSMIC: COSV65485033; COSMIC: COSV65485033;