Single gene variants causing deafness in Asian Indians

Abstract

Congenital deafness is one of the common disorders, with some common genes accounting for most of the cases. One in 1000 children are born with sensorineural hearing loss, and of that 50% are hereditary. In the Mediterranean Europeans, 80% of the nonsyndromic recessive deafness is due to homozygous mutation in GJB2, the 35del G allele. InWestern population, the GJB2 variation have been found in up to 30-40% cases. In Indians, the GJB2 variants have been found in up to 20% cases, mostly from central and southern India. In the present study, DNA was extracted from blood using standard methods. This was used to perform targeted gene capture using a custom capture kit. Multiple genes causing deafness were sequenced by next-generation sequencing to mean >80-100x coverage on Illumina sequencing platform. We found variants in GJB2, WFS1, FGF3, EYA4, MYO7A. and CHD7 genes. Most of these variants were pathogenic and novel, and possibly causative. Deafness is most commonly due to the autosomal dominant genes but in severe cases of early onset deafness, autosomal recessive genes may contribute in our population. In selected families of severe prelingual deafness, prenatal diagnosis can be done.