A Study of Kindreds with Hereditary Deafness from Sindh Province of Pakistan

Abstract

Deafness is one of the most complex birth defects in human population, which affect as many as three of every 1,000 babies born. Given the unique biological requirements of sound transduction and the selective advantage conferred upon a species capable of sensitive sound detection, it is not surprising that up to 1% of the approximately 30,000 or more human genes are necessary for hearing. The autosomal recessive forms of deafness are generally the most severe and are most exclusively caused by cochlear defects (sensorineural deafness). Out of 68 known DFNB loci, most of the recessively inherited forms of hearing impairment cause a phenotypically identical severe to profound, prelingual hearing loss except DFNB2-MY07A, DFNB8110-TMPRSS3 and DFNB16-STRC, which cause a delayed, childhood onset hearing impairment. Until novv, about 37 genes have been identified causing autosomal recessive deafness. The study at hand incorporates three Sindhi families (A, B, C) showing symptoms of recessive non-syndromic deafness. Affected individuals from all the three families have a history of prelingual profound hearing impairment and use sign language for communication. Linkage in the three families was searched by using polymorphic microsatellite markers corresponding to candidate genes involved in related autosomal recessive non-syndromic deafness phenotypes. Linkage to several known deafness loci was conclusively excluded, thus indicating the involvement of novel loci responsible for deafness in these three families.