Investigating the relationship of genetic mutations in GJB2 and linkage analysis of DFNB4 Locus in a group of non-syndromic hearing impaired people with autosomal recessive inheritance in Hormozgan

Background & Objective: Deafness is the most common sensory disorder in humans which is highly heterogeneous. Among its various types, autosomal recessive non-syndromic hearing loss (ARNSHL) is responsible for 80% of pre-speech congenital cases of hearing loss. The purpose of this study was to investigate the genetic linkage of DFNB4 locus in hearing impaired families in Hormozgan. Method: Ten deaf large families in the Hormozgan province were selected. A hearing impaired person was selected from each family tree and sequence of the GJB2 gene in regards of coding regions' mutations was investigated using sequencing method. STR markers of DFNB4 locus in families with no mutation in GJB2 were amplified using PCR and after determining the type alleles, they were analyzed for linkage. Results: In one among the ten studied families, GJB2 mutation was observed. The nine other families were entered for linkage studies and no linkage was found in the said families. Conclusion: Due to the high heterogeneity of loci associated with ARNSHL, other factors may be involved in the cause of deafness in families, without mutations in the GJB2 gene and the investigated locus. Therefore it is recommended to study other loci and more families in this matter