Definition

DFNB1A (GJB2-related hearing loss) is the most common genetic cause of hereditary sensorineural hearing loss, resulting from biallelic pathogenic variants in the GJB2 gene that cause loss of function of the connexin-26 protein. Connexin-26 forms gap junction channels between supporting cells in the cochlea, playing a role in potassium recirculation; its dysfunction leads to degeneration of hair cells and non-progressive sensorineural hearing loss that appears at birth or in early childhood.

Gene/region examined

GJB2 - Exon 2

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Hereditary, autosomal recessive (some specific GJB2 variants can also cause autosomal dominant hearing loss, but DFNB1A is recessive).

Related Tests

Inheritance Patterns

Describes how a genetic condition is passed on within a family. There are five main patterns

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Carrier (Heterozygous / Homozygous)

Why it matters: In autosomal recessive inheritance, when each parent is a carrier (while both appear healthy), the chance of their child being born with the disease is 25% in each

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VUS (Variant of Uncertain Significance)

This is the situation where the test has detected a change in the DNA, but the role of this change in the development of disease is unconfirmed.

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How to Read a Genetic Test Result (Positive / Negative / VUS)

A genetic test result falls into three main categories

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Types of Genetic Tests

A genetic test is a type of medical test that detects changes in genes, chromosomes or proteins. Today there are more than 77,000 genetic tests available.

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