GENE REFERENCE / HGNC:4284

GJB2

gap junction protein beta 2

protein-coding gene13q12.11Gene information

What does this gene do?

The GJB2 gene provides instructions for making a protein called gap junction beta 2, more commonly known as connexin 26. Connexin 26 is a member of the connexin protein family. Connexin proteins form channels called gap junctions that permit the transport of nutrients, charged atoms (ions), and signaling molecules between adjoining cells. The size of the gap junction and the types of particles that move through it are determined by the particular connexin proteins that make up the channel. Gap junctions made with connexin 26 transport potassium ions and certain small molecules.

Connexin 26 is found in cells throughout the body, including the inner ear. Because of its presence in the inner ear, especially the snail-shaped structure called the cochlea, researchers are interested in this protein's role in hearing. Hearing requires the conversion of sound waves to electrical nerve impulses. This conversion involves many processes, including maintenance of the proper level of potassium ions in the inner ear. Some studies indicate that channels made with connexin 26 help to maintain the correct level of potassium ions. Other research suggests that connexin 26 is required for the maturation of certain cells in the cochlea.

Connexin 26 is also found in the skin. It is thought to play a role in the growth, maturation, and stability of the skin's outermost layer, the epidermis.

Source: MedlinePlus, National Library of Medicine. Source publication: 2025-04-03. Source review: 2016-01.

ClinGen reviews

ClinGen reviews the evidence linking a particular gene to a condition. Each rating below describes the strength of that link. It does not classify a variant in your DNA file.

Condition	Inheritance	Evidence
nonsyndromic genetic hearing lossMONDO:0019497 · Evaluated 2024-09-24	Autosomal recessive	DefinitiveHearing Loss Gene Curation Expert Panel
hearing loss disorderMONDO:0005365 · Evaluated 2018-06-26	Autosomal dominant	DefinitiveHearing Loss Gene Curation Expert Panel

ClinVar records

These numbers show what has been submitted to ClinVar. They cannot tell you how likely you are to have a condition.

Submitted alleles: 745
Submissions for variants in or overlapping this gene: 3,172
Submissions explicitly reporting this gene: 3,094
Alleles reported pathogenic / likely pathogenic: 267
VariationIDs with uncertain significance: 213
VariationIDs with conflicting classifications: 62

The rows count different things: alleles, submissions or VariationIDs. Their categories can overlap, so do not add them together. Pathogenic/likely pathogenic counts exclude structural variants that merely overlap a gene. A dash in the source means “not reported,” not zero.

NCBI produces the gene-summary file each week using counts recorded at the start of the month. The numbers may differ from those on the live ClinVar website. Read the field definitions ↗

View this gene in ClinVar ↗

YOUR DNA FILE

Can your DNA file tell you about GJB2?

From a DNA test kit (such as 23andMe, AncestryDNA or MyHeritage). These kits check a fixed list of about 600,000 to 700,000 positions across your whole genome. ClinVar lists 267 alleles in GJB2 reported as pathogenic or likely pathogenic. A kit checks only some of these positions, and often none of them.

From whole genome sequencing (a VCF file). Sequencing reads most of your genome. Your file lists the places where your DNA differs from the reference genome. Some regions are hard to sequence, including parts of some genes that have near-identical copies elsewhere, and a VCF file does not record which positions were read well.

If a variant is not in your file, that does not mean you don’t have it.

What BioDecode checks

BioDecode compares every variant in your file with ClinVar, on your own computer. For each match, it shows the ClinVar classification, the review status and the condition it was reported for. Your file is not uploaded.

A ClinVar classification applies to one particular variant and the condition it was reported for. It does not tell you about other variants in GJB2.

BioDecode cannot fill gaps in your test, diagnose a condition or replace clinical testing.

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