Absence of GJB3 and GJB6 mutations in Moroccan familial and sporadic patients with autosomal recessive non-syndromic deafness.

UNLABELLED: Deafness is an etiologically heterogeneous trait with a wide variety of genetic and environmental causes. It is generally considered that genetic factors account for at least half of all cases of profound congenital deafness, which can be classified in two categories - dominant or recessive - according to the mode of inheritance and in two types - syndromic or non-syndromic - according to the presence or absence of some other specific clinical features. Mutations in the gene GJB2, encoding the gap junction protein connexion 26, are considered to be responsible for up to 50% of familial cases of autosomal recessive non-syndromic hearing loss and for up to 15-30% of the sporadic cases. It has also been reported that mutations in the GJB6 and GJB3 genes contribute to autosomal recessive and autosomal dominant hearing defects in many populations.

OBJECTIVE

The aim of this study was to screen mutations in GJB6 and GJB3 genes in Moroccan patients with autosomal non-syndromic hearing loss.

METHODS

We carried out 95 patients with non-syndromic hearing loss. The patients, who were negative for homozygous mutations in GJB2 gene and GJB6-D13S1830 deletion, were tested for the coding regions of GJB6 and GJB3 genes by direct sequencing.

RESULTS

No deleterious mutation in GJB6 and GJB3 genes was detected in all deaf patients tested. Only a C357T silent transition in heterozygous state was found in the GJB3 gene in one patient.

CONCLUSION

The present data demonstrated that mutations in the GJB6 and GJB3 genes are an infrequent cause of non-syndromic deafness in Morocco.