Study of the Association of DFNB3 Locus with Autosomal Recessive Non-Syndromic Hearing Loss in Iranian Deaf Population Using Genetic Linkage Analysis

Hearing loss is a common sensory disorder that typically illustrates genetic heterogeneity in human populations. The incidence of congenital hearing loss is estimated at 1 in 500 births of which approximately 70% of cases are attributed to genetic factors. Genetic hearing impairment can be classified as either syndromic or non-syndromic and among non-syndromic hearing loss autosomal recessive (ALNSHL) accounts for approximately 75-80% of cases. This type of hearing loss is extremely heterogeneous and includes over 100 loci. For recessive deafness, most frequent genes are GJB2, SLC26A4, MYO15A, OTOF, and CDH23 in worldwide. This study aimed to determine the role of MYO15A (DFNB3) gene mutations in Iranian deaf population using linkage analysis.

To investigate the frequency of DFNB3 gene mutation, linkage analysis was performed in 30 Iranian families with over three deaf child and negative GJB2. The negative mutations pedigrees for these gene mutations were then tested for the linkage to DFNB3 (MYO15A) locus, using short tandem repeat (STR) markers.

Mutation 35delG was identified in 5 families out of 30 by sequencing the coding region of GJB2 gene. One family showed linkage to DFNB3 locus.

Based on the results of this study, DFNB3 locus is the third cause of deafness after DFNB1 (GJB2) and DFNB4 (SLC26A4).