Genetic Linkage Analysis of 15 DFNB Loci in a Group of Iranian Families with Autosomal Recessive Hearing Loss

Background: hearing loss (hl) is the most frequent sensory birth defect in humans. autosomal recessive non-syndromichl (arnshl) is the most common type of hereditary hl. it is extremely heterogeneous and over 70 loci (known asdfnb) have been identified. this study was launched to determine the relative contribution of more frequent loci in acohort of arnshl families.methods: thirty-seven iranian families including 36 arnshl families and 1 family with pendred syndrome each with. 4 affected individuals, from seven provinces of iran, were ascertained. dfnb1 contribution was initially studied bydna sequencing of gjb2 and linkage analysis using the relative str markers. the excluded families were then subjectedto homozygosity mapping for fifteen arnshl loci.results: sixteen families were found to be linked to seven different known loci, including dfnb1 (6 families), dfnb4 (3families +1 family with pendred syndrome), dfnb63 (2 families), dfnb2 (1 family), dfnb7/11 (1 family), dfnb9 (1 family)and dfnb21 (1 family). dna sequencing of the corresponding genes is in progress to identify the pathogenic mutations.conclusion: the genetic causes were clarified in 43.2% of the studied families, giving an overview of the causes ofarnshl in iran. dfnb4 is ranked second after dfnb1 in the studied cohort. more genetic and epigenetic investigationswill have to be done to reveal the causes in the remaining families.