GENE REFERENCE / HGNC:4283

GJB1

gap junction protein beta 1

protein-coding geneXq13.1Gene information

What does this gene do?

The GJB1 gene provides instructions for making a protein called connexin-32 (also known as gap junction beta 1). This protein is a member of the gap junction connexin family, which plays a role in cell communication by forming channels, or gap junctions, between cells. Gap junctions speed the transport of nutrients, charged particles (ions), and small molecules that carry communication signals between cells.

The connexin-32 protein is made in several tissues, including those of the liver, pancreas, kidney, and nervous system. In the nervous system, this protein is located in the cell membrane of specialized cells called Schwann cells and oligodendrocytes. Schwann cells are found in the peripheral nervous system, which consists of nerves connecting the brain and spinal cord (central nervous system) to muscles and sensory cells that detect sensations such as touch, pain, heat, and sound. Oligodendrocytes are located in the central nervous system.

Schwann cells and oligodendrocytes surround nerves and are involved in the production and long-term maintenance of a fatty substance called myelin. Myelin forms a protective coating (or sheath) around certain nerve cells that ensures the smooth and rapid transmission of nerve impulses.

The connexin-32 protein forms channels through the myelin sheath, allowing efficient transport and communication between the outer myelin layers and the interior of the Schwann cell or oligodendrocyte.

Source: MedlinePlus, National Library of Medicine. Source publication: 2020-08-18. Source review: 2018-10.

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
Charcot-Marie-Tooth disease X-linked dominant 1MONDO:0010549 · Evaluated 2020-01-14	X-linked	DefinitiveCharcot-Marie-Tooth Disease 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: 1,013
Submissions for variants in or overlapping this gene: 1,885
Submissions explicitly reporting this gene: 1,734
Alleles reported pathogenic / likely pathogenic: 275
VariationIDs with uncertain significance: 426
VariationIDs with conflicting classifications: 68

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 GJB1?

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 275 alleles in GJB1 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 GJB1.

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

Buy BioDecode See a sample report →Check file compatibility →