rs116840818

chrX-71223894-G-AchrX-71223894-G-T

Variant summary

Our verdict is Pathogenic. Variant got 16 ACMG points: 16P and 0B. PM1 PM2 PP3_Strong PP5_Very_Strong

The NM_000166.6(GJB1):c.187G>A(p.Val63Ile) variant causes a missense change involving the alteration of a conserved nucleotide. The variant allele was found at a frequency of 0.00000274 in 1,096,578 control chromosomes in the GnomAD database, with no homozygous occurrence. There are 1 hemizygotes in GnomAD. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. V63F) has been classified as Uncertain significance.

• Frequency:
  • Genomes: not found (cov: 22)
  • Exomes 𝑓: 0.0000027 (0 hom. 1 hem.)
• Consequence: GJB1 NM_000166.6 missense
• Clinical Significance: Pathogenic criteria provided, multiple submitters, no conflicts P:7 U:2 O:1
• Conservation: PhyloP100: 10.0

Genes affected

GJB1 (HGNC:4283): (gap junction protein beta 1) This gene encodes a member of the gap junction protein family. The gap junction proteins are membrane-spanning proteins that assemble to form gap junction channels that facilitate the transfer of ions and small molecules between cells. According to sequence similarities at the nucleotide and amino acid levels, the gap junction proteins are divided into two categories, alpha and beta. Mutations in this gene cause X-linked Charcot-Marie-Tooth disease, an inherited peripheral neuropathy. Alternatively spliced transcript variants encoding the same protein have been found for this gene. [provided by RefSeq, Oct 2008]

ACMG classification

Verdict is Pathogenic. Variant got 16 ACMG points.

• PM1: In a hotspot region, there are 11 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 14 uncertain in NM_000166.6
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.985
• PP5: Variant X-71223894-G-A is Pathogenic according to our data. Variant chrX-71223894-G-A is described in ClinVar as [Pathogenic]. Clinvar id is 21081.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars. Variant chrX-71223894-G-A is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	UniProt
GJB1	NM_000166.6	c.187G>A	p.Val63Ile	missense_variant	2/2	ENST00000361726.7
GJB1	NM_001097642.3	c.187G>A	p.Val63Ile	missense_variant	2/2
GJB1	XM_011530907.3	c.187G>A	p.Val63Ile	missense_variant	2/2

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Appris	UniProt
GJB1	ENST00000361726.7	c.187G>A	p.Val63Ile	missense_variant	2/2	1	NM_000166.6	P1

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome AF: 0.00000274 AC: 3 AN: 1096578 Hom.: 0 Cov.: 31 AF XY: 0.00000276 AC XY: 1 AN XY: 361988

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.00

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000238

Gnomad4 OTH exome AF: 0.0000217

GnomAD4 genome Cov.: 22

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:7 Uncertain:2 Other:1

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:5

Pathogenic, criteria provided, single submitter	clinical testing	CeGaT Center for Human Genetics Tuebingen	Feb 01, 2017	- -
Pathogenic, criteria provided, single submitter	clinical testing	GeneDx	Mar 27, 2023	Not observed in large population cohorts (gnomAD); Missense variants in this gene are often considered pathogenic (HGMD); In silico analysis supports that this missense variant does not alter protein structure/function; This variant is associated with the following publications: (PMID: 10093067, 30569560, 15006706, 20301548, 9099841, 12477701, 9633821, 12542510, 11393532, 17100997, 9364054, 25025039, 8162049, 9361298, 32376792) -
Pathogenic, criteria provided, single submitter	clinical testing	Athena Diagnostics	Mar 30, 2016	- -
Pathogenic, no assertion criteria provided	clinical testing	Joint Genome Diagnostic Labs from Nijmegen and Maastricht, Radboudumc and MUMC+	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Clinical Genetics, Academic Medical Center	-	- -

Charcot-Marie-Tooth disease Pathogenic:1 Uncertain:1

Uncertain significance, no assertion criteria provided	literature only	Inherited Neuropathy Consortium	-	- -
Pathogenic, no assertion criteria provided	clinical testing	Natera, Inc.	Sep 16, 2020	- -

Charcot-Marie-Tooth disease X-linked dominant 1 Uncertain:1 Other:1

not provided, no classification provided	literature only	GeneReviews	-	- -
Uncertain significance, no assertion criteria provided	literature only	Inherited Neuropathy Consortium Ii, University Of Miami	Jan 06, 2016	- -

Charcot-Marie-Tooth Neuropathy X Pathogenic:1

Pathogenic, criteria provided, single submitter

clinical testing

Invitae

Dec 20, 2023

This sequence change replaces valine, which is neutral and non-polar, with isoleucine, which is neutral and non-polar, at codon 63 of the GJB1 protein (p.Val63Ile). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individuals with Charcot-Marie-Tooth disease (PMID: 8162049, 10093067, 12542510). It has also been observed to segregate with disease in related individuals. ClinVar contains an entry for this variant (Variation ID: 21081). 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 GJB1 protein function. Experimental studies have shown that this missense change affects GJB1 function (PMID: 9364054, 11393532, 15006706). For these reasons, this variant has been classified as Pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.21
BayesDel_addAF	Pathogenic	0.48	D
BayesDel_noAF	Pathogenic	0.45
Cadd	Uncertain	24
Dann	Uncertain	0.99
DEOGEN2	Pathogenic	0.84	D;D;D;D;D;.;D
FATHMM_MKL	Uncertain	0.96	D
M_CAP	Pathogenic	0.77	D
MetaRNN	Pathogenic	0.99	D;D;D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Uncertain	2.8	M;M;M;M;.;.;M
MutationTaster	Benign	1.0	A;A;A
PrimateAI	Uncertain	0.70	T
PROVEAN	Benign	-0.99	N;.;N;.;N;.;N
REVEL	Pathogenic	0.72
Sift	Uncertain	0.0090	D;.;D;.;D;.;D
Sift4G	Uncertain	0.020	D;.;D;.;D;.;D
Polyphen		1.0	D;D;D;D;.;.;D
Vest4		0.78
MutPred		0.96		Loss of catalytic residue at V63 (P = 0.2318);Loss of catalytic residue at V63 (P = 0.2318);Loss of catalytic residue at V63 (P = 0.2318);Loss of catalytic residue at V63 (P = 0.2318);Loss of catalytic residue at V63 (P = 0.2318);Loss of catalytic residue at V63 (P = 0.2318);Loss of catalytic residue at V63 (P = 0.2318);
MVP		0.95
MPC		1.7
ClinPred		0.98	D
GERP RS		3.7
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.63
gMVP		0.97

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: rs116840818; hg19: chrX-70443744;