rs1555937244

Positions:

• chrX-71224266-A-G

Variant summary

Our verdict is Likely pathogenic. Variant got 9 ACMG points: 9P and 0B. PM1 PM2 PP3_Strong PP5

The NM_000166.6(GJB1):​c.559A>G​(p.Lys187Glu) variant causes a missense change involving the alteration of a conserved nucleotide. The variant was absent in control chromosomes in GnomAD project. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Conflicting classifications of pathogenicity (no stars).

• Frequency: Genomes: not found (cov: 22)
• Consequence: GJB1 NM_000166.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 9.32

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 Likely_pathogenic. Variant got 9 ACMG points.

• PM1: In a chain Gap junction beta-1 protein (size 282) in uniprot entity CXB1_HUMAN there are 4 pathogenic changes around while only 0 benign (100%) in NM_000166.6
• PM2: Very rare variant in population databases, with high coverage
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.977
• PP5: Variant X-71224266-A-G is Pathogenic according to our data. Variant chrX-71224266-A-G is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 543925.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=2, Likely_pathogenic=1}. Variant chrX-71224266-A-G is described in Lovd as [Pathogenic].

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GJB1	NM_000166.6	c.559A>G	p.Lys187Glu	missense_variant	2/2	ENST00000361726.7	NP_000157.1
GJB1	NM_001097642.3	c.559A>G	p.Lys187Glu	missense_variant	2/2		NP_001091111.1
GJB1	XM_011530907.3	c.559A>G	p.Lys187Glu	missense_variant	2/2		XP_011529209.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GJB1	ENST00000361726.7	c.559A>G	p.Lys187Glu	missense_variant	2/2	1	NM_000166.6	ENSP00000354900.6

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 22

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Athena Diagnostics

Mar 07, 2023

This variant has been identified in at least one individual with clinical features associated with this gene. This variant has not been reported in large, multi-ethnic general populations (http://gnomad.broadinstitute.org). Computational tools predict that this variant is damaging. The variant is located in a region that is considered important for protein function and/or structure. -

not specified Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Mendelics

May 04, 2022

- -

Charcot-Marie-Tooth disease Uncertain:1

Uncertain significance, no assertion criteria provided

literature only

Inherited Neuropathy Consortium

-

- -

Charcot-Marie-Tooth Neuropathy X Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Oct 29, 2023

This sequence change replaces lysine, which is basic and polar, with glutamic acid, which is acidic and polar, at codon 187 of the GJB1 protein (p.Lys187Glu). This variant is not present in population databases (gnomAD no frequency). This missense change has been observed in individual(s) with Charcot-Marie-Tooth disease (PMID: 9361298). ClinVar contains an entry for this variant (Variation ID: 543925). 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 expected to disrupt GJB1 protein function with a positive predictive value of 80%. 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	Pathogenic	0.99
BayesDel_addAF	Pathogenic	0.74	D
BayesDel_noAF	Pathogenic	0.82
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Pathogenic	0.99	D;D;D;D;D
FATHMM_MKL	Uncertain	0.97	D
LIST_S2	Pathogenic	1.0	.;.;.;.;D
M_CAP	Pathogenic	0.95	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	4.2	H;H;H;H;H
PrimateAI	Pathogenic	0.83	D
PROVEAN	Uncertain	-3.9	D;.;D;.;D
REVEL	Pathogenic	0.98
Sift	Pathogenic	0.0	D;.;D;.;D
Sift4G	Pathogenic	0.0	D;.;D;.;D
Polyphen		1.0	D;D;D;D;D
Vest4		0.98
MutPred		0.81		Loss of methylation at K187 (P = 0.002);Loss of methylation at K187 (P = 0.002);Loss of methylation at K187 (P = 0.002);Loss of methylation at K187 (P = 0.002);Loss of methylation at K187 (P = 0.002);
MVP		1.0
MPC		2.2
ClinPred		1.0	D
GERP RS		5.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.98
gMVP		1.0

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: rs1555937244; hg19: chrX-70444116;