Frequency of the 35delG allele causing nonsyndromic recessive deafness in the Algerian patients.

Deafness is a heterogeneous disorder showing different patterns of inheritance and involving a multitude of different genes. Mutations in the GJB2 gene encoding connexin 26 (Cx26) protein are a major cause for non-syndromic autosomal recessive and sporadic deafness. Among these mutations, the c.35delG deletion is the most common mutation for sensorineural deafness. One hundred sixteen persons from fifty-eight families were tested by the method based on the principle of PCR-mediated-site-directed mutagenesis (PSDM), followed by a Bsl1 digestion. Mutation c.35delG was diagnosed in sixteen families (11 homozygotes and 5 heterozygotes). The low allelic frequency (17.24%) and low ratio of individuals homozygous (13.8%) and heterozygous (6.9%) for the c.35delG mutation suggest that there are other mutations in the GJB2 gene or other genes responsible for deafness in the Algerian population. This study reports a significant association (P=0.003) between first cousin consanguinity and non-syndromic prelingual deafness.