rs749693224

Positions:

• chr13-20189522-A-C

Variant summary

Our verdict is Uncertain significance. Variant got 5 ACMG points: 5P and 0B. PM1 PP3_Moderate PP5

The NM_004004.6(GJB2):​c.60T>G​(p.Ile20Met) variant causes a missense change involving the alteration of a non-conserved nucleotide. The variant allele was found at a frequency of 0.0000155 in 1,613,978 control chromosomes in the GnomAD database, with no homozygous occurrence. 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: 𝑓 0.0000066 (0 hom., cov: 33)
  • Exomes 𝑓: 0.000016 (0 hom.)
• Consequence: GJB2 NM_004004.6 missense
• Clinical Significance: Conflicting classifications of pathogenicity criteria provided, conflicting classifications P:2 U:5
• Conservation: PhyloP100: -1.32

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]

ACMG classification

Verdict is Uncertain_significance. Variant got 5 ACMG points.

• PM1: In a helix (size 19) in uniprot entity CXB2_HUMAN there are 12 pathogenic changes around while only 1 benign (92%) in NM_004004.6
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.885
• PP5: Variant 13-20189522-A-C is Pathogenic according to our data. Variant chr13-20189522-A-C is described in ClinVar as [Conflicting_classifications_of_pathogenicity]. Clinvar id is 438615.We mark this variant Likely_pathogenic, oryginal submissions are: {Uncertain_significance=5, Pathogenic=1, Likely_pathogenic=1}.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	MANE	Protein	UniProt
GJB2	NM_004004.6	c.60T>G	p.Ile20Met	missense_variant	2/2	ENST00000382848.5	NP_003995.2
GJB2	XM_011535049.3	c.60T>G	p.Ile20Met	missense_variant	2/2		XP_011533351.1

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	#exon/exons	TSL	MANE	Protein	Appris	UniProt
GJB2	ENST00000382848.5	c.60T>G	p.Ile20Met	missense_variant	2/2	1	NM_004004.6	ENSP00000372299.4
GJB2	ENST00000382844.2	c.60T>G	p.Ile20Met	missense_variant	1/1	6		ENSP00000372295.1

Frequencies

GnomAD3 genomes AF: 0.00000657 AC: 1 AN: 152168 Hom.: 0 Cov.: 33

Gnomad AFR AF: 0.00

Gnomad AMI AF: 0.00

Gnomad AMR AF: 0.00

Gnomad ASJ AF: 0.000288

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

GnomAD3 exomes AF: 0.0000360 AC: 9 AN: 249864 Hom.: 0 AF XY: 0.0000518 AC XY: 7 AN XY: 135200

Gnomad AFR exome AF: 0.00

Gnomad AMR exome AF: 0.00

Gnomad ASJ exome AF: 0.000794

Gnomad EAS exome AF: 0.00

Gnomad SAS exome AF: 0.00

Gnomad FIN exome AF: 0.00

Gnomad NFE exome AF: 0.00000892

Gnomad OTH exome AF: 0.00

GnomAD4 exome AF: 0.0000164 AC: 24 AN: 1461810 Hom.: 0 Cov.: 33 AF XY: 0.0000165 AC XY: 12 AN XY: 727208

Gnomad4 AFR exome AF: 0.00

Gnomad4 AMR exome AF: 0.00

Gnomad4 ASJ exome AF: 0.000689

Gnomad4 EAS exome AF: 0.00

Gnomad4 SAS exome AF: 0.00

Gnomad4 FIN exome AF: 0.00

Gnomad4 NFE exome AF: 0.00000180

Gnomad4 OTH exome AF: 0.0000497

GnomAD4 genome AF: 0.00000657 AC: 1 AN: 152168 Hom.: 0 Cov.: 33 AF XY: 0.00 AC XY: 0 AN XY: 74346

Gnomad4 AFR AF: 0.00

Gnomad4 AMR AF: 0.00

Gnomad4 ASJ AF: 0.000288

Gnomad4 EAS AF: 0.00

Gnomad4 SAS AF: 0.00

Gnomad4 FIN AF: 0.00

Gnomad4 NFE AF: 0.00

Gnomad4 OTH AF: 0.00

Alfa AF: 0.0000425 Hom.: 0

Bravo AF: 0.00000756

ExAC AF: 0.00000824 AC: 1

EpiCase AF: 0.00

EpiControl AF: 0.0000593

ClinVar

Significance: Conflicting classifications of pathogenicity

Submissions summary: Pathogenic:2 Uncertain:5

Revision: criteria provided, conflicting classifications

Submissions by phenotype

Autosomal recessive nonsyndromic hearing loss 1A Uncertain:3

Uncertain significance, criteria provided, single submitter	clinical testing	Counsyl	Jan 31, 2018	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Genomic Diagnostic Laboratory, Division of Genomic Diagnostics, Children's Hospital of Philadelphia	May 09, 2017	- -
Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Apr 27, 2017	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Autosomal dominant nonsyndromic hearing loss 3A Pathogenic:1 Uncertain:1

Uncertain significance, criteria provided, single submitter	clinical testing	Illumina Laboratory Services, Illumina	Apr 27, 2017	This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). Publications were found based on this search. However, the evidence from the literature, in combination with allele frequency data from public databases where available, was not sufficient to rule this variant in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -
Pathogenic, criteria provided, single submitter	research	Laboratory of Prof. Karen Avraham, Tel Aviv University	Nov 25, 2024	The p.(Ile20Met) variant was detected in five compound heterozygous probands, three for p.I20M/c.167delT and two for p.I20M/c.35delG, all of them with mild-moderate HL. Segregation analysis in these families supported pathogenicity of the variant. Another proband with compound heterozygosity for p.I20M/p.V37I reported normal hearing but refused to have his hearing tested. -

not provided Pathogenic:1

Likely pathogenic, criteria provided, single submitter

clinical testing

Labcorp Genetics (formerly Invitae), Labcorp

Jan 15, 2024

This sequence change replaces isoleucine, which is neutral and non-polar, with methionine, which is neutral and non-polar, at codon 20 of the GJB2 protein (p.Ile20Met). This variant is present in population databases (rs749693224, gnomAD 0.08%). This missense change has been observed in individual(s) with deafness (PMID: 12172394, 12910486, 17666888; Invitae). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. ClinVar contains an entry for this variant (Variation ID: 438615). 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 GJB2 protein function. This variant disrupts the p.Ile20 amino acid residue in GJB2. Other variant(s) that disrupt this residue have been determined to be pathogenic (PMID: 11313763, 12189487, 16217030, 16380907). This suggests that this residue is clinically significant, and that variants that disrupt this residue are likely to be disease-causing. In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. -

Ichthyosis, hystrix-like, with hearing loss Uncertain:1

Uncertain significance, criteria provided, single submitter

clinical testing

Illumina Laboratory Services, Illumina

Apr 27, 2017

This variant was observed as part of a predisposition screen in an ostensibly healthy population. A literature search was performed for the gene, cDNA change, and amino acid change (where applicable). No publications were found based on this search. Allele frequency data from public databases did not allow this variant to be ruled in or out of causing disease. Therefore, this variant is classified as a variant of unknown significance. -

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.29
BayesDel_addAF	Pathogenic	0.28	D
BayesDel_noAF	Pathogenic	0.16
CADD	Benign	15
DANN	Uncertain	0.99
DEOGEN2	Uncertain	0.73	D;D;D
Eigen	Benign	-0.47
Eigen_PC	Benign	-0.68
FATHMM_MKL	Benign	0.30	N
LIST_S2	Benign	0.84	.;.;T
M_CAP	Pathogenic	0.32	D
MetaRNN	Pathogenic	0.89	D;D;D
MetaSVM	Uncertain	0.71	D
MutationAssessor	Pathogenic	3.1	M;M;M
PrimateAI	Uncertain	0.59	T
PROVEAN	Benign	-1.3	N;N;.
REVEL	Uncertain	0.60
Sift	Uncertain	0.0020	D;D;.
Sift4G	Uncertain	0.0050	D;D;.
Polyphen		0.84	P;P;P
Vest4		0.54
MutPred		0.93		Gain of disorder (P = 0.0567);Gain of disorder (P = 0.0567);Gain of disorder (P = 0.0567);
MVP		0.76
MPC		0.15
ClinPred		0.66	D
GERP RS		-5.8
Varity_R		0.82
gMVP		0.86

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: rs749693224; hg19: chr13-20763661;