X-71224221-C-T

Variant names:

• chrX-71224221-C-T
• rs104894811
• NM_000166.6:c.514C>T

Variant summary

Our verdict is Pathogenic. The variant received 19 ACMG points: 19P and 0B. PM1 PM2 PM5 PP2 PP3_Strong PP5_Very_Strong

The NM_000166.6(GJB1):​c.514C>T​(p.Pro172Ser) 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 Likely pathogenic (★★). Another variant affecting the same amino acid position, but resulting in a different missense (i.e. P172R) has been classified as Uncertain significance.

• Frequency: Genomes: not found (cov: 22)
• Consequence: GJB1 NM_000166.6 missense
• Clinical Significance: Pathogenic/Likely pathogenic criteria provided, multiple submitters, no conflicts P:4
• Conservation: PhyloP100: 7.90
• Publications: 6 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: Pathogenic. The variant received 19 ACMG points.

• PM1: In a hotspot region, there are 16 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 31 uncertain in NM_000166.6
• PM2: Very rare variant in population databases, with high coverage
• PM5: Other missense variant is known to change same aminoacid residue: Variant chrX-71224221-C-G is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 637168.Status of the report is criteria_provided_single_submitter, 1 stars.
• 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, 0.985
• PP5: Variant X-71224221-C-T is Pathogenic according to our data. Variant chrX-71224221-C-T is described in ClinVar as Pathogenic/Likely_pathogenic. ClinVar VariationId is 10432.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GJB1	NM_000166.6	c.514C>T	p.Pro172Ser	missense_variant	Exon 2 of 2	ENST00000361726.7	NP_000157.1
GJB1	NM_001097642.3	c.514C>T	p.Pro172Ser	missense_variant	Exon 2 of 2		NP_001091111.1
GJB1	NM_001440770.1	c.514C>T	p.Pro172Ser	missense_variant	Exon 3 of 3		NP_001427699.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GJB1	ENST00000361726.7	c.514C>T	p.Pro172Ser	missense_variant	Exon 2 of 2	1	NM_000166.6	ENSP00000354900.6

Frequencies

GnomAD3 genomes Cov.: 22

GnomAD2 exomes AF: 0.00000566 AC: 1 AN: 176561 AF XY: 0.00

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.00

Gnomad EAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00

Gnomad OTH exome AF: 0.00

GnomAD4 exome Cov.: 32

GnomAD4 genome Cov.: 22

Alfa AF: 0.00 Hom.: 0

ExAC AF: 0.00000824 AC: 1

ClinVar

Significance: Pathogenic/Likely pathogenic

Submissions summary: Pathogenic:4

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

not provided Pathogenic:2

Jul 10, 2024

GeneDx

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Reported previously in an affected male with Charcot-Marie-Tooth disease; however, no further clinical or segregation information was provided (PMID: 8266101); Published function studies showed discordant results (PMID: 9592087, 15006706); Not observed at significant frequency in large population cohorts (gnomAD); Missense variants in this gene are a common cause of disease and they are underrepresented in the general population; In silico analysis supports that this missense variant has a deleterious effect on protein structure/function; This variant is associated with the following publications: (PMID: 34750751, 17353473, 21297078, 22342665, 9592087, 15006706, 9856562, 21692908, 8266101) -

May 01, 2018

CeGaT Center for Human Genetics Tuebingen

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

- -

Charcot-Marie-Tooth Neuropathy X Pathogenic:1

Oct 20, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

This sequence change replaces proline, which is neutral and non-polar, with serine, which is neutral and polar, at codon 172 of the GJB1 protein (p.Pro172Ser). This variant is present in population databases (rs104894811, gnomAD 0.005%). This missense change has been observed in individuals with CMTX (PMID: 8266101, 17353473, 21692908). ClinVar contains an entry for this variant (Variation ID: 10432). 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. Experimental studies are conflicting or provide insufficient evidence to determine the effect of this variant on GJB1 function (PMID: 9592087, 15006706). This variant disrupts the p.Pro172 amino acid residue in GJB1. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 9633821, 9856562, 21692908, 27098783). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Charcot-Marie-Tooth disease X-linked dominant 1 Pathogenic:1

Dec 24, 1993

OMIM

Significance: Pathogenic

Review Status: no assertion criteria provided

Collection Method: literature only

- -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Pathogenic	1.0
BayesDel_addAF	Pathogenic	0.62	D
BayesDel_noAF	Pathogenic	0.82
CADD	Uncertain	24
DANN	Pathogenic	1.0
DEOGEN2	Pathogenic	0.99	D;D;D;D;D
FATHMM_MKL	Uncertain	0.95	D
LIST_S2	Pathogenic	1.0	.;.;.;.;D
M_CAP	Pathogenic	0.97	D
MetaRNN	Pathogenic	0.98	D;D;D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Pathogenic	3.8	H;H;H;H;H
PhyloP100		7.9
PrimateAI	Uncertain	0.62	T
PROVEAN	Pathogenic	-7.8	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		0.30
MutPred		0.82		Loss of ubiquitination at K167 (P = 0.2432);Loss of ubiquitination at K167 (P = 0.2432);Loss of ubiquitination at K167 (P = 0.2432);Loss of ubiquitination at K167 (P = 0.2432);Loss of ubiquitination at K167 (P = 0.2432);
MVP		1.0
MPC		1.9
ClinPred		1.0	D
GERP RS		5.0
RBP_binding_hub_radar		0.0
RBP_regulation_power_radar		1.7
Varity_R		0.97
gMVP		1.0
Mutation Taster		=1/99	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: rs104894811; hg19: chrX-70444071;