[Congenital hearing loss. Molecular genetic diagnosis of connexin genes and genetic counselling].

BACKGROUND

About 50% of congenital non-syndromic hearing impairment is caused by genetic factors. Research on the genetics of deafness has revealed a vast number of relevant genes. Mutations in the GJB2 gene have been shown to be the most common in several populations.

METHODS

Mutation analysis of the genes for connexin 26, 30 and 31 (GJB2, GJB6 and GJB3) was performed in 67 patients with profound hearing loss.

RESULTS

Of the participants, 9% had two pathogenic mutations in the GJB2 gene. Pedigree information indicates that in these families further offspring have a 25% to a 100% chance of having hearing impairment.

CONCLUSIONS

Patients with non-syndromic hearing impairment should be offered molecular diagnostics of the GJB2 gene. Genetic counseling is mandatory for mutation carriers in order to advise them on the individual consequences of the gene test results.