Mutations in the connexin26/GJB2 gene are the most common event in non-syndromic hearing loss among the German population

Congenital sensorineural hearing loss affects approximately 1/1,000 live births. Mutations in the gene encoding connexin26 (GJB2) have been described as a major cause of genetic nonsyndromic hearing impairment. Additionally, another gap junction gene, connexin30 (GJB6), was found to be responsible for hereditary hearing loss. We have studied 134 patients with severe to profound hearing loss or deafness and 13 patients with mild to moderate nonsyndromic sensorineural hearing loss in order to evaluate the prevalence of connexin26 and connexin30 mutations in Germany. Mutations in the connexin26 gene were found in 30 patients (22%) with profound to severe hearing impairment whereas only one novel single nucleotide polymorphism (396G-->A) in the connexin30 gene was detected. Among the 13 patients with mild to moderate hearing loss neither mutations in the connexin26 nor in the connexin30 gene could be detected. These results demonstrate that mutations in the connexin26 gene are also a frequent cause of hereditary non-syndromic hearing loss in Germany. Therefore a screening of mutations in the connexin26 gene should be performed in every case of non-syndromic hearing loss of unknown origin.