Genetic heterogeneity in GJB2, COL4A3, ATP6V1B1 and EDNRB variants detected among hearing impaired families in Morocco.

Abstract

Deafness is the most prevalent human sensorineural defect. It may occur as a result of an external auditory canal involvement, or a deficiency in the sound conduction mechanism, or an impairment of the cochlea, the cochlear nerve or central auditory perception. The genetic causes are the most common, as approximately 70% of hearing disorders are of hereditary origin, divided into two groups, syndromic (associated with other symptoms) and no syndromic (isolated deafness). A whole exome sequencing was performed to identify the genetic cause of hearing loss in six Moroccan families and Sanger sequencing was used to validate mutations in these genes. The results of four out of the six families revealed four genetic variants in the genes GJB2, COL4A3, ATP6V1B1 and EDNRB responsible for non-syndromic and syndromic hearing loss. Multiple Bioinformatics programs and molecular modelling predicted the pathogenic effect of these mutations. We identified in Moroccan deaf patients four homozygous mutations. These results show the importance of whole exome sequencing to identify pathogenic mutations in heterogeneous disorders with multiple genes responsible.