Establishing Ancestry through Pedigree of a Village with High Prevalence of Hearing-Impaired

Abstract

Introduction: Population-based surveys into the cause of deafness have consistently shown that a high percentage (50%) of childhood deafness can be attributed to genetic causes. The flip side to genetic testing in population surveys is the operational difficulties associated with carrying it out. The present study was therefore planned with the aim of establishing ancestry through pedigree of a village with high prevalence of hearing-impaired. Materials and Methods: A two-stage study design was used to conduct this study. The first stage involved a house-to-house survey to identify hearing-impaired whereas the second stage involved clinical examination for hearing impairment. Results: Of a total of 2522 individuals studied, 80 were identified as hearing-impaired yielding a crude prevalence of 3.17%. The pedigree analysis of the whole village revealed a common ancestry. Discussion: In the late 20th century, deaf-mutism became a subject of debate and social isolation for Dadhkai villagers. A highlight of Dadhkai has been that its surroundings are not deaf-friendly as is expected. Consequently, as intermarriage flourished, the village community increasingly started resembling each other. This could have led to increase in autosomal recessive inheritance of deafness. Similar studies such as evaluation of six patients from two generations from a large sibship of Turkish ethnicity with double consanguinity in the family support the evidence. Conclusion: Flourishing of intermarriage and thereby consanguinity may be the reason behind high number of hearing impaired in this village. Therefore population based genetic counseling may be the key to prevent the same in future.