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.