13-20189580-A-G

Variant names:

Variant summary

Our verdict is Pathogenic. The variant received 12 ACMG points: 12P and 0B. PM3_SupportingPVS1PM5PM2_Supporting

This summary comes from the ClinGen Evidence Repository: The c.2T>C (p.Met1Thr) variant in GJB2 may cause a truncated or absent protein by altering the start codon of the coding sequence and is predicted to lead to the omission of a critical region of the protein. There have been multiple pathogenic variants observed in the region between this site and the next expected start codon (PVS1; ClinVar Variation IDs: 21387, 188758). There are also multiple pathogenic/likely pathogenic start-loss variants at this position which may indicate that this residue is critical to the function of the protein (ClinVar Variation IDs: 44729, 2070085, 550716, 551915). This variant has been observed in 0.0074% (8/107882) of the African population in the All of Us database (PM2_Supporting). It was identified in 1 patient with bilateral sensorineural hearing loss who also harbored an assumed trans pathogenic variant (0.5 PM3_Supporting points; Athena Diagnostics internal data, SCV001143666.1). In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive hearing loss based on the ACMG/AMP criteria applied as specified by the Hearing Loss Expert Panel: PVS1, PM2_Supporting, PM3_Supporting (VCEP specifications version 2; 10.18.2023). LINK:https://erepo.genome.network/evrepo/ui/classification/CA6904336/MONDO:0019497/005

Frequency

Genomes: 𝑓 0.000026 ( 0 hom., cov: 33)

Exomes 𝑓: 6.8e-7 ( 0 hom. )

Consequence

GJB2
NM_004004.6 start_lost

Scores

Clinical Significance

Pathogenic reviewed by expert panel P:9

Conservation

PhyloP100: 9.13

Publications

7 publications found

Variant links:

Genes affected

GJB2 (HGNC:4284): (gap junction protein beta 2) This gene encodes a member of the gap junction protein family. The gap junctions were first characterized by electron microscopy as regionally specialized structures on plasma membranes of contacting adherent cells. These structures were shown to consist of cell-to-cell channels that facilitate the transfer of ions and small molecules between cells. The gap junction proteins, also known as connexins, purified from fractions of enriched gap junctions from different tissues differ. 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 are responsible for as much as 50% of pre-lingual, recessive deafness. [provided by RefSeq, Oct 2008]

GJB2 Gene-Disease associations (from GenCC):

Bart-Pumphrey syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: Genomics England PanelApp, Labcorp Genetics (formerly Invitae), G2P
ichthyosis, hystrix-like, with hearing loss
Inheritance: AD Classification: DEFINITIVE, STRONG Submitted by: G2P, Genomics England PanelApp
keratoderma hereditarium mutilans
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp, G2P
palmoplantar keratoderma-deafness syndrome
Inheritance: AD Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet, G2P
autosomal recessive nonsyndromic hearing loss 1A
Inheritance: AR Classification: DEFINITIVE, STRONG Submitted by: Labcorp Genetics (formerly Invitae), Laboratory for Molecular Medicine, G2P, PanelApp Australia
hearing loss, autosomal recessive
Inheritance: AR Classification: DEFINITIVE, SUPPORTIVE Submitted by: Orphanet, ClinGen
autosomal dominant keratitis-ichthyosis-hearing loss syndrome
Inheritance: AD Classification: STRONG, MODERATE Submitted by: Genomics England PanelApp, Ambry Genetics
autosomal dominant nonsyndromic hearing loss 3A
Inheritance: AD Classification: STRONG Submitted by: Ambry Genetics, Labcorp Genetics (formerly Invitae)
autosomal dominant nonsyndromic hearing loss
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet
KID syndrome
Inheritance: AD Classification: SUPPORTIVE Submitted by: Orphanet

GJB2 links:

ENSG00000296095 (HGNC:):

ENSG00000296095 links:

Genome browser will be placed here

ACMG classification

Classification was made for transcript

Our verdict: Pathogenic. The variant received 12 ACMG points.

PVS1

For more information check the summary or visit ClinGen Evidence Repository.

PM2

For more information check the summary or visit ClinGen Evidence Repository.

PM3

For more information check the summary or visit ClinGen Evidence Repository.

PM5

For more information check the summary or visit ClinGen Evidence Repository.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GJB2	NM_004004.6 link	c.2T>C	p.Met1?	start_lost	Exon 2 of 2	ENST00000382848.5	NP_003995.2	P29033H9U1J4
GJB2	XM_011535049.3 link	c.2T>C	p.Met1?	start_lost	Exon 2 of 2		XP_011533351.1	P29033H9U1J4

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	UniProt
GJB2	ENST00000382848.5 link	c.2T>C	p.Met1?	start_lost	Exon 2 of 2	1	NM_004004.6	ENSP00000372299.4	P29033
GJB2	ENST00000382844.2 link	c.2T>C	p.Met1?	start_lost	Exon 1 of 1	6		ENSP00000372295.1	P29033
ENSG00000296095	ENST00000736390.1 link	n.232-4000T>C		intron_variant	Intron 1 of 3

Frequencies

GnomAD3 genomes

AF:

0.0000263

AC:

AN:

152148

Hom.:

Cov.:

show subpopulations

Gnomad AFR

AF:

0.0000966

Gnomad AMI

AF:

0.00

Gnomad AMR

AF:

0.00

Gnomad ASJ

AF:

0.00

Gnomad EAS

AF:

0.00

Gnomad SAS

AF:

0.00

Gnomad FIN

AF:

0.00

Gnomad MID

AF:

0.00

Gnomad NFE

AF:

0.00

Gnomad OTH

AF:

0.00

GnomAD2 exomes

AF:

0.00000401

AC:

AN:

249204

AF XY:

0.00

show subpopulations

Gnomad AFR exome

AF:

0.00

Gnomad AMR exome

AF:

0.0000289

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

AF:

6.84e-7

AC:

AN:

1461720

Hom.:

Cov.:

AF XY:

0.00

AC XY:

AN XY:

727154

show subpopulations

African (AFR)

AF:

0.0000299

AC:

AN:

33470

American (AMR)

AF:

0.00

AC:

AN:

44724

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

26136

East Asian (EAS)

AF:

0.00

AC:

AN:

39700

South Asian (SAS)

AF:

0.00

AC:

AN:

86254

European-Finnish (FIN)

AF:

0.00

AC:

AN:

53414

Middle Eastern (MID)

AF:

0.00

AC:

AN:

5722

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

1111920

Other (OTH)

AF:

0.00

AC:

AN:

60380

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.475

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

GnomAD4 genome

AF:

0.0000263

AC:

AN:

152148

Hom.:

Cov.:

AF XY:

0.0000269

AC XY:

AN XY:

74332

show subpopulations

African (AFR)

AF:

0.0000966

AC:

AN:

41424

American (AMR)

AF:

0.00

AC:

AN:

15278

Ashkenazi Jewish (ASJ)

AF:

0.00

AC:

AN:

3472

East Asian (EAS)

AF:

0.00

AC:

AN:

5188

South Asian (SAS)

AF:

0.00

AC:

AN:

4830

European-Finnish (FIN)

AF:

0.00

AC:

AN:

10606

Middle Eastern (MID)

AF:

0.00

AC:

AN:

316

European-Non Finnish (NFE)

AF:

0.00

AC:

AN:

68028

Other (OTH)

AF:

0.00

AC:

AN:

2094

Allele Balance Distribution

Red line indicates average allele balance

Average allele balance: 0.488

Heterozygous variant carriers

0.00

0.20

0.40

0.60

0.80

0.95

Allele balance

Age Distribution

Genome Het

Variant carriers

<30

30-35

35-40

40-45

45-50

50-55

55-60

60-65

65-70

70-75

75-80

>80

Age

Alfa

AF:

0.0000329

Hom.:

Bravo

AF:

0.0000151

ESP6500AA

AF:

0.000227

AC:

ESP6500EA

AF:

0.00

AC:

ExAC

AF:

0.0000165

AC:

ClinVar

Significance: Pathogenic

Submissions summary: Pathogenic:9

Revision: reviewed by expert panel

LINK: link

Submissions by phenotype

not provided

Pathogenic:3

Nov 09, 2018

Athena Diagnostics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The variant disrupts the natural start codon, and is therefore predicted to result in the loss of a functional protein. Found in at least one symptomatic patient, and found in general population data that is consistent with pathogenicity. -

Jan 07, 2022

GeneDx

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Initiation codon variant in a gene for which loss-of-function is a known mechanism of disease; Not observed at significant frequency in large population cohorts (gnomAD); Identified in one individual with a low grade glioma from a cohort of cancer patients as part of a large investigation of cancer predisposition variants (Huang et al., 2018); This variant is associated with the following publications: (PMID: 29625052) -

Nov 17, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

This sequence change affects the initiator methionine of the GJB2 mRNA. The next in-frame methionine is located at codon 34. This variant is present in population databases (rs371086981, gnomAD 0.003%). Disruption of the initiator codon has been observed in individual(s) with autosomal recessive nonsyndromic deafness (PMID: 9482292, 29605365). ClinVar contains an entry for this variant (Variation ID: 371781). Studies have shown that disruption of the initiator codon alters GJB2 gene expression (PMID: 12189493). This variant disrupts a region of the GJB2 protein in which other variant(s) (p.Gly12Val) have been determined to be pathogenic (PMID: 10982180, 19371219, 24158611, 25288386). This suggests that this is a clinically significant region of the protein, and that variants that disrupt it are likely to be disease-causing. For these reasons, this variant has been classified as Pathogenic. -

Nonsyndromic genetic hearing loss

Pathogenic:2

Aug 22, 2022

Women's Health and Genetics/Laboratory Corporation of America, LabCorp

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

Variant summary: GJB2 c.2T>C (p.Met1Thr) alters the initiation codon and is predicted to result either in absence of the protein or truncation of the encoded protein due to translation initiation at a downstream codon. Three of four in-silico tools predict a damaging effect of the variant on protein function. The variant allele was found at a frequency of 4e-06 in 249204 control chromosomes (gnomAD). The available data on variant occurrences in the general population are insufficient to allow any conclusion about variant significance. To our knowledge, no occurrence of c.2T>C in individuals affected with Non-Syndromic Hearing Loss and no experimental evidence demonstrating its impact on protein function have been reported. This variant disrupts the start codon for protein translation (ATG becomes ACG) and the next start codon is 32 amino acids downstream. Variants affecting the same codon (M1V) and other codons within the N terminal 32 amino acids (such as L6P, Q7P, L10P, G12V, R32C, etc) have been reported in many affected individuals, suggesting the functional importance of this codon and the N terminal region of this protein (example: PMID: 29605365, PMID: 9482292). Five clinical diagnostic laboratories have submitted clinical-significance assessments for this variant to ClinVar after 2014 and all laboratories classified the variant as pathogenic(n=3)/likely pathogenic(n=2). Based on the evidence outlined above, the variant was classified as likely pathogenic. -

Mar 28, 2024

ClinGen Hearing Loss Variant Curation Expert Panel

Significance:Pathogenic

Review Status:reviewed by expert panel

Collection Method:curation

The c.2T>C (p.Met1Thr) variant in GJB2 may cause a truncated or absent protein by altering the start codon of the coding sequence and is predicted to lead to the omission of a critical region of the protein. There have been multiple pathogenic variants observed in the region between this site and the next expected start codon (PVS1; ClinVar Variation IDs: 21387, 188758). There are also multiple pathogenic/likely pathogenic start-loss variants at this position which may indicate that this residue is critical to the function of the protein (ClinVar Variation IDs: 44729, 2070085, 550716, 551915). This variant has been observed in 0.0074% (8/107882) of the African population in the All of Us database (PM2_Supporting). It was identified in 1 patient with bilateral sensorineural hearing loss who also harbored an assumed trans pathogenic variant (0.5 PM3_Supporting points; Athena Diagnostics internal data, SCV001143666.1). In summary, this variant meets criteria to be classified as pathogenic for autosomal recessive hearing loss based on the ACMG/AMP criteria applied as specified by the Hearing Loss Expert Panel: PVS1, PM2_Supporting, PM3_Supporting (VCEP specifications version 2; 10.18.2023). -

Autosomal recessive nonsyndromic hearing loss 1A

Pathogenic:1

Oct 11, 2016

Counsyl

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

This submission and the accompanying classification are no longer maintained by the submitter. For more information on current observations and classification, please contact variantquestions@myriad.com. -

Autosomal dominant keratitis-ichthyosis-hearing loss syndrome;C0265964:Mutilating keratoderma;C0266004:Knuckle pads, deafness AND leukonychia syndrome;C1835672:Palmoplantar keratoderma-deafness syndrome;C1865234:Ichthyosis, hystrix-like, with hearing loss;C2673759:Autosomal recessive nonsyndromic hearing loss 1A;C2675750:Autosomal dominant nonsyndromic hearing loss 3A

Pathogenic:1

May 04, 2024

Fulgent Genetics, Fulgent Genetics

Significance:Pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

- -

Autosomal dominant nonsyndromic hearing loss 3A

Pathogenic:1

Oct 11, 2016

Counsyl

Significance:Likely pathogenic

Review Status:no assertion criteria provided

Collection Method:clinical testing

GJB2-related disorder

Pathogenic:1

Nov 22, 2022

PreventionGenetics, part of Exact Sciences

Significance:Likely pathogenic

Review Status:criteria provided, single submitter

Collection Method:clinical testing

The GJB2 c.2T>C variant is predicted to disrupt the translation initiation site (Start loss). To our knowledge, this variant has not been reported in a patient with hearing loss or deafness. However, two other variants that also result in start loss (p.Met1Ile, p.Met1Val) have been reported in patients with nonsyndromic hearing loss (Huang et al. 2018. PubMed ID: 29605365; Estivill et al. 1998. PubMed ID: 9482292). This variant is reported in 0.0029% of alleles in individuals of Latino descent in gnomAD (http://gnomad.broadinstitute.org/variant/13-20763719-A-G). This variant is interpreted as likely pathogenic. -

Computational scores

Source: dbNSFP v4.3

Name

Calibrated prediction

Score

Prediction

BayesDel_addAF

Pathogenic

0.50

BayesDel_noAF

Pathogenic

0.56

CADD

Benign

(source)

DANN

Benign

0.97

DEOGEN2

Uncertain

0.71

D;D;D

Eigen

Uncertain

0.24

Eigen_PC

Uncertain

0.30

FATHMM_MKL

Pathogenic

0.99

LIST_S2

Uncertain

0.90

.;.;D

M_CAP

Pathogenic

0.63

MetaRNN

Pathogenic

0.94

D;D;D

MetaSVM

Pathogenic

0.95

PhyloP100

9.1

PROVEAN

Pathogenic

-5.5

D;D;.

REVEL

Pathogenic

0.89

Sift

Pathogenic

0.0

D;D;.

Sift4G

Pathogenic

0.0010

D;D;.

Polyphen

0.50

P;P;P

Vest4

0.94

MVP

0.97

ClinPred

0.97

GERP RS

5.4

PromoterAI

0.017

Neutral

(source)

Varity_R

0.95

gMVP

0.94

Mutation Taster

=5/195

disease causing (ClinVar)

(source)

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

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Variant summary

Frequency

Consequence

Scores

Clinical Significance

Conservation

Publications

ACMG classification

Transcripts

RefSeq

Ensembl

Frequencies

Age Distribution

ClinVar

Submissions by phenotype

Computational scores

Splicing

Publications

Other links and lift over