Low incidence of GIPC3 variants among the prelingual hearing impaired from southern India.

The broad spectrum of causal variants in the newly discovered GIPC3 gene is well reflected in worldwide studies. Except for one missense variant, none of the reported variants had reoccurred, thus reflecting the intragenic heterogeneity. We screened all the six coding exons of GIPC3 gene in a large cohort of 177 unrelated prelingual hearing impaired after excluding the common GJB2, GJB6 nuclear and A1555G mitochondrial variants. We observed a single homozygous pathogenic frameshift variant c.685dupG (p.A229GfsX10), accounting for a low incidence (0.56%) of GIPC3 variants in south Indian population. GIPC3 being a rare gene as a causative for deafness, the allelic spectra perhaps became much more diverse from population to population, thus resulting in a minimal recurrence of the variants in our study, that were reported by authors from other parts of the globe.

Autosomal dominant hearing loss resulting from p.R75Q mutation in the GJB2 gene: nonsyndromic presentation in a South Indian family.

Mutations in the GJB2 gene encoding the gap junction protein Connexin 26 have been associated with autosomal recessive as well as dominant nonsyndromic hearing loss. Owing to the involvement of connexins in skin homeostasis, GJB2 mutations have also been associated with syndromic forms of hearing loss showing various skin manifestations. We report an assortatively mating hearing impaired family of south Indian origin with three affected members spread over two generations, having p.R75Q mutation in the GJB2 gene in the heterozygous condition. The inheritance pattern was autosomal dominant with mother and son being affected. Dermatological and histopathologic examinations showed absence of palmoplantar keratoderma. To the best of our knowledge, this is the first report from India on p.R75Q mutation in the GJB2 gene with nonsyndromic hearing loss.