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# GJB2 (connexin 26) hearing loss

The most common genetic cause of deafness from birth in many populations: a recessive defect in a protein that recycles potassium in the inner ear.

Updated Nov 13, 2026

On this page

- The basics What it is
- Who gets it
- Causes
- Pathophysiology

- Clinical Symptoms and signs
- Red flags
- Diagnosis
- Complications
- Prognosis

- Treatment Treatment

- Study Test yourself

## What it is

Autosomal recessive nonsyndromic sensorineural hearing loss caused by biallelic variants in GJB2, which encodes the gap-junction protein connexin 26.

See it in 3D

- [Cochlea](https://durgical.com/en/anatomy/cochlea/)

## Who gets it

Genetic causes explain over half of congenital hearing loss in high-income countries, and GJB2 is the single most common gene in many populations.

## Causes

- Biallelic GJB2 variants; c.35delG is frequent in people of European and Mediterranean ancestry
- Autosomal recessive inheritance: usually hearing parents who are carriers

## Pathophysiology

Connexin 26 forms gap junctions between supporting cells of the [cochlea](https://durgical.com/en/anatomy/cochlea/), which recycle potassium back to the endolymph after hair cells fire. Without it, potassium handling fails and hair cells degenerate, causing sensorineural hearing loss without other features.

## Symptoms and signs

- Bilateral sensorineural hearing loss present at birth, from mild to profound
- Usually stable, not progressive
- Normal balance and no other organ involvement

## Red flags

- A failed newborn hearing screen
- Delayed speech in a young child

## Diagnosis

**Clinical**
Suspect in a child with congenital bilateral sensorineural hearing loss and no other findings.

**Tests**
Newborn hearing screening, then auditory brainstem response and audiometry; GJB2 testing is usually the first genetic test, followed by a hearing-loss gene panel if negative. Congenital cytomegalovirus is the main non-genetic cause to exclude.

**Imaging**
[Temporal bone](https://durgical.com/en/anatomy/temporal-bone/) imaging is normal in GJB2 hearing loss.

## Treatment

**Rehabilitation**
Early hearing aids and, for severe or profound loss, cochlear implants, which work well in GJB2 deafness.

**Rehabilitation**
Early language support, including sign language according to the family's choice.

**Follow-up**
Regular audiology follow-up and genetic counselling for the family.

## Complications

- Delayed language and learning if the loss is not found early

## Prognosis

With early detection and intervention, language and school outcomes can be good.

## Test yourself

Think of the answer, then tap the question to see it.

## What does connexin 26 do in the cochlea?

It forms gap junctions that recycle potassium back to the endolymph after hair-cell activity.

## Why is a genetic cause found before imaging in many deaf infants?

GJB2 is the commonest cause and testing it is simple; temporal bone imaging is normal in this condition.

## Which non-genetic cause of congenital hearing loss must be ruled out?

Congenital cytomegalovirus infection.

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Educational information, not medical advice. For any symptom, see a health professional.

Sources: [Nonsyndromic hearing loss: MedlinePlus Genetics](https://medlineplus.gov/genetics/condition/nonsyndromic-hearing-loss/) (MedlinePlus, US National Library of Medicine, 2026); [GJB2 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/gjb2/) (MedlinePlus, US National Library of Medicine, 2026).

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Representative model, for educational purposes only.

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License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/conditions/gjb2-hearing-loss/