Bilateral Hearing Loss (35delG)

Bilateral hearing loss linked to the 35delG variant is caused by a change in the GJB2 gene, which can lead to hearing loss in both ears. The GJB2 gene carries the instructions for making a protein called connexin 26, which helps form gap junctions. These are tiny channels that allow ions and small molecules to pass between neighbouring cells in the inner ear, a process essential for normal hearing.

How the variant affects hearing

The 35delG variant is the loss of a single building block (nucleotide) in the GJB2 gene. This disrupts the genetic instructions, so the connexin 26 protein is either not made or is made in a non-functional form. Without it, the inner ear cannot develop or function normally, resulting in hearing loss.

Key points

• Variable severity: the degree of hearing loss can range from mild to profound.
• Common cause: it is most often found in people of European descent and is thought to account for up to half of all genetic hearing loss cases in this group.
• Often present from birth: as a genetic variant, it is typically associated with hearing loss that is present from early life.

Who might consider testing

Testing for 35delG may be helpful for people with a personal or family history of hearing loss, or those wishing to understand the underlying genetic cause of their condition.

• GJB2 gene (35delG variant)

No special preparation required.

For blood tests, we recommend drinking plenty of water beforehand to ensure smooth sample collection. If you are taking any regular medication, continue to do so unless advised otherwise by your doctor.