An audiological and genetic profile of hearing of learners suspected of familial hearing loss attending schools for the deaf in KwaZulu-Natal.

Abstract

This study focused on genetic familial hearing loss, concentrating on learners attending schools for the Deaf in Kwazulu Natal .The study sought to identify the audiological profile characteristics of suspected genetic familial hearing loss in the learners and their family members with hearing loss. Currently there is a scarcity of research in the area of genetics and hearing loss in South Africa. The study aimed at providing both an audiological and genetic profile of familial hearing loss of learners with a history of hearing loss in the family. A quantitative multicase study research design was chosen. Participants were identified based on a positive family history of hearing loss in learner records and the referral from the school Audiologists. An audiological assessment and family pedigree was conducted on affected learners and their families who volunteered to participate in the research. The study sample consisted of 40 learners from 25 families with 70 affected participants who underwent audiological assessments and a family pedigree analysis, of which 31 were male and 39 were female. The pedigree analysis of the 25 families also presented 417 individuals who were reported to have normal hearing and 20 individuals with a reported hearing loss that were unable to undergo audiological testing in the study. The study identified an autosomal dominant inheritance present in 32% (8) of families an autosomal recessive inheritance in 56% (14) and a presumed co-incidental familial hearing loss in 12% (3) of families. The audiological and genetic profile of families within the study, revealed significant differences between the profile of autosomal dominant and autosomal recessive hearing loss. The autosomal recessive group revealed a profile of hearing loss that was predominately congenital, prelingual, sensorineural, severe to profound in severity and flat in configuration. The autosomal dominant inheritance revealed a profile that was both prelingual and postlingual in onset with a moderate to severe sensorineural hearing loss and a sloping configuration. The results of the study are supported by other studies with regard to the description and auditory profile differences of autosomal recessive and autosomal dominant hearing loss. An understanding of the audiometric profiles of genetic familial hearing loss, will be useful to health professionals when assessing and managing these families with a history of hearing loss. It is believed that a standard method of profiling genetic familial hearing loss and the use of a family pedigree analysis, would be beneficial to professionals who encounter families with hearing loss. The role of the multidisciplinary team which includes Audiologists, geneticists and genetic counsellors in the family with a familial hearing loss are invaluable. This study provided data on the current incidence of genetic familial hearing loss at schools for the deaf in the province of KwaZulu-Natal. It is expected that with the advancement of research in the area of genetic familial hearing loss, an increase in professionals in the field of genetics such as geneticists and genetic counsellors will be available.