rs913934445

Variant names:

• chrX-71223855-T-C
• rs913934445
• NM_000166.6:c.148T>C

Your query was ambiguous. Multiple possible variants found:

• chrX-71223855-T-C
• chrX-71223855-T-G

Variant summary

Our verdict is Likely pathogenic. The variant received 8 ACMG points: 8P and 0B. PM1 PM2 PP2 PP3_Moderate PP5

The NM_000166.6(GJB1):​c.148T>C​(p.Ser50Pro) variant causes a missense change. 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). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. S50A) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 23)
• Consequence: GJB1 NM_000166.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:1 U:3
• Conservation: PhyloP100: 5.84
• Publications: 5 publications found

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]

GJB1 Gene-Disease associations (from GenCC):

• Charcot-Marie-Tooth disease X-linked dominant 1

  Inheritance: XL Classification: DEFINITIVE, STRONG, MODERATE, SUPPORTIVE Submitted by: Orphanet, PanelApp Australia, ClinGen, Labcorp Genetics (formerly Invitae)
• X-linked progressive cerebellar ataxia

  Inheritance: XL Classification: SUPPORTIVE Submitted by: Orphanet

ACMG classification

Our verdict: Likely_pathogenic. The variant received 8 ACMG points.

• PM1: In a hotspot region, there are 14 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 23 uncertain in NM_000166.6
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 135 curated pathogenic missense variants (we use a threshold of 10). The gene has 4 curated benign missense variants. Trascript score misZ: NaN (below the threshold of 3.09). GenCC associations: The gene is linked to Charcot-Marie-Tooth disease X-linked dominant 1, X-linked progressive cerebellar ataxia.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.928
• PP5: Variant X-71223855-T-C is Pathogenic according to our data. Variant chrX-71223855-T-C is described in ClinVar as Conflicting_classifications_of_pathogenicity. ClinVar VariationId is 430122.

Variant Effect in Transcripts

ACMG analysis was done for transcript: NM_000166.6. You can select a different transcript below to see updated ACMG assignments.

RefSeq Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GJB1	NM_000166.6	MANE Select	c.148T>C	p.Ser50Pro	missense	Exon 2 of 2	NP_000157.1
	GJB1	NM_001097642.3		c.148T>C	p.Ser50Pro	missense	Exon 2 of 2	NP_001091111.1
	GJB1	NM_001440770.1		c.148T>C	p.Ser50Pro	missense	Exon 3 of 3	NP_001427699.1

Ensembl Transcripts

Selected	Gene	Transcript	Tags	HGVSc	HGVSp	Effect	Exon Rank	Protein	UniProt
	GJB1	ENST00000361726.7	TSL:1 MANE Select	c.148T>C	p.Ser50Pro	missense	Exon 2 of 2	ENSP00000354900.6
	GJB1	ENST00000374029.2	TSL:5	c.148T>C	p.Ser50Pro	missense	Exon 2 of 2	ENSP00000363141.1
	GJB1	ENST00000447581.2	TSL:5	c.148T>C	p.Ser50Pro	missense	Exon 3 of 3	ENSP00000407223.2

Frequencies

GnomAD3 genomes Cov.: 23

GnomAD4 exome Cov.: 31

GnomAD4 genome Cov.: 23

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:1 Uncertain:3

Revision: criteria provided, conflicting classifications

Submissions by phenotype

not provided Pathogenic:1

May 22, 2017

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

A variant that is likely pathogenic has been identified in the GJB1 gene. The S50P variant has been previously reported in two families with a clinical diagnosis of axonal CMT (Latour et al., 1997). The S50P variant is not observed in large population cohorts (Lek et al., 2016; 1000 Genomes Consortium et al., 2015; Exome Variant Server). The S50P variant is a non-conservative amino acid substitution, which is likely to impact secondary protein structure as these residues differ in polarity, charge, size and/or other properties. This substitution occurs at a position that is conserved across species. In silico analysis is inconsistent in its predictions as to whether or not the variant is damaging to the protein structure/function. Missense variants in nearby residues (S49P/Y, F51L, C53S/Y) have been reported in the Human Gene Mutation Database in association with CMT (Stenson et al., 2014), supporting the functional importance of this region of the protein. Therefore, this variant is likely pathogenic; however, the possibility that it is benign cannot be excluded

not specified Uncertain:1

Dec 02, 2016

Athena Diagnostics

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Charcot-Marie-Tooth disease Uncertain:1

Inherited Neuropathy Consortium

Significance: Uncertain significance

Review Status: no assertion criteria provided

Collection Method: literature only

Charcot-Marie-Tooth Neuropathy X Uncertain:1

Apr 20, 2021

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Uncertain significance

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces serine with proline at codon 50 of the GJB1 protein (p.Ser50Pro). The serine residue is moderately conserved and there is a moderate physicochemical difference between serine and proline. This variant is not present in population databases (ExAC no frequency). This variant has been observed in individual(s) with Charcot-Marie-Tooth disease (PMID: 10732813). ClinVar contains an entry for this variant (Variation ID: 430122). Algorithms developed to predict the effect of missense changes on protein structure and function (SIFT, PolyPhen-2, Align-GVGD) all suggest that this variant is likely to be tolerated, but these predictions have not been confirmed by published functional studies and their clinical significance is uncertain. 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 v4.9

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	0.87
BayesDel_addAF	Pathogenic	0.59	D
BayesDel_noAF	Pathogenic	0.61
CADD	Uncertain	24
DANN	Uncertain	0.99
DEOGEN2	Pathogenic	0.84	D
FATHMM_MKL	Uncertain	0.89	D
LIST_S2	Uncertain	0.92	D
M_CAP	Pathogenic	0.80	D
MetaRNN	Pathogenic	0.93	D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	1.5	L
PhyloP100		5.8
PrimateAI	Uncertain	0.65	T
PROVEAN	Benign	-1.2	N
REVEL	Pathogenic	0.70
Sift	Uncertain	0.0010	D
Sift4G	Uncertain	0.0050	D
Polyphen		0.85	P
Vest4		0.81
MutPred		0.81		Loss of disorder (P = 0.0935)
MVP		1.0
MPC		1.1
ClinPred		0.80	D
GERP RS		4.6
Varity_R		0.50
gMVP		0.99
Mutation Taster		=5/95	disease causing (ClinVar)

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

Other links and lift over

dbSNP: rs913934445; hg19: chrX-70443705;