Hearing Loss, Non-Syndromic (GJB2 and GJB6)

Non-syndromic sensorineural hearing loss (NSHL) is a common disability affecting approximately 1 in 1000 newborns. In approximately 50% of children with congenital deafness the hearing loss is due to inherited causes. The most common form of inherited hearing loss is autosomal recessive non-syndromic hearing loss (AR-NSHL), which affects approximately 1 in every 2500 children.

Many different genes have been shown to play a role in NSHL.Mutations in the in the GJB2 gene have been implicated in 50 to 80% of AR-NSHL cases, making this the most common cause of AR-NSHL. The GJB2 gene encodes a gap junction protein called connexin 26, which is important in the development of the inner ear. A second gap junction protein, connexin 30 encoded by the GJB6 gene, can also cause AR-NSHL. In particular a recurrent deletion in the GJB6 gene (delGJB6-D13S1830) has been reported to cause AR-NSHL in approximately 20% of patients who also have one GJB2 gene mutation.

The strategy used for testing for non-syndromic hearing loss is complete sequencing of the coding region and flanking exon/intron boundaries of the GJB2 gene, and direct mutation testing for the recurrent deletion mutation (delGJB6-D13S1830) in the GJB6 gene.

See related information sheet: Non-syndromic Hearing Loss, Autosomal Recessive GJB2 & GJB6