Etiology and associated GJB2 mutations in Mauritanian children with non-syndromic hearing loss.

Abstract

Origins of all hearing impairment forms may be divided into genetic mutations and acquired influence. Both carry damage to the inner ear structure resulting in a mild to profound dysfunction of the auditory system. The purpose of this study was to assess the different etiologies of deafness in two reference centers for hearing-impaired children in Nouakchott/Mauritania. Data on gender, age, consanguinity, etiology and family history of deafness were gathered by interviewing the custodians of 139 children with hearing loss. DNA of pupils with hereditary non-syndromic deafness was then screened for GJB2 mutations by sequencing methods. Postnatal hearing loss was found in 36 (25.8%) out of the 139 children surveyed. The main etiologies of this group were infections caused by meningitis (12.9%) and measles (2.8%). Unknown and ototoxic origins accounted for, respectively, 5.7 and 3.5%. In 103 (74.1%) children, deafness was identified near after the time of birth and, therefore, presumed as congenital. 56.8% of deaf children had consanguineous parents. Two GJB2 mutations, c.del35G with an allele frequency of 4.7% and R32C (3.7%) were detected. Infections such as meningitis and measles were the most prevalent causes of postnatal deafness. In cases of congenital hearing impairment, two GJB2 allele variants, i.e., del35G and R32C (3.7%) were detected. Extended genetic testing is recommended for a more comprehensive determination of congenital causes.