Résumé
The etiology of hearing loss is heterogeneous. One of the causes is the genetic hearing loss which may be syndromic or non-syndromic. Mutations in the gap junction of beta 2 [GJB2] gene which encode connexin 26 [CX26] protein are a major cause of non-syndromic hearing loss. The aim of this work was to assess mutations of CX26 gene in adults with non-syndromic hearing loss. Twenty seven patients with non-syndromic hearing loss, family history of hearing loss and consanguinity were examined for Cx26 gene mutations by polymerase chain reaction [PCR] and subsequent sequencing. Relatives of these patients were examined by Multi-Frequency Pure Tone Audiometry [MFPTA]. The percentage of positive mutations in patients with hearing loss was 70.4%, Four types of Cx26 gene mutations were found in these patients. They were: 35delG [deletion/frameshift mutation], RI43W mutation [missense mutation with nucleotide change 426C-T at codon 143 R-W], V271 mutation [polymorphic mutation with nucleotide change 79G-A at codon 27V-l] and 235delC [deletion/frameshift mutation]. 35delG mutation was the most frequent type of mutation as it was detected in 78.9% of cases Moreover, 70% of cases with this mutation were homozygous. On the other hand, notches of MFPTA were found in 52.63% of the relatives. We can conclude that Knowledge of the genetic cause of hearing loss is important for accurate genetic counseling and early diagnosis for timely intervention and treatment options. Also, the use of MFPTA in diagnosis of congenital hearing loss as it gives immediate results less expensive and can be done by conventional audiometer