GJB2 and Hearing impairment: Under the broad title of ‘non-syndromic hearing loss,’ the criteria give specific guidelines for: congenital hearing impairment, auditory neuropathy spectrum disorder, and autosomal dominant deafness.9 In terms of congenital deafness and prior understanding, the guidelines strongly recommended genetic testing of GJB2 and SCL26A4 genes prior to inclusion in the project.