فاطمه نعمتی زرگران

Hearing loss is a common sensorial disorder. There are approximately 360 million affected people all over the world. More than 50% of hearing loss is because of genetics factors. About 70% of inherited hearing loss is due to non-syndromic hearing impairment that Autosomal- recessive inheritance is responsible for about 80% of cases. Autosomal recessive non syndromic hearing loss is very heterogeneous and more than 50 genes have been identified for it. The aimof this study was to investigate the role of DFNB42 (ILDR1) and DFNB35 (ESRRB) mutations in 25 families with ARNSHL from Khuzestan Iran.
This descriptive study was based on linkage analysis and selected 6 STR markers for each locus. This study was performed for 300 individuals from 25 families that had at least two affected, also they had consanguineous marriage. In this study, it was investigated mutations of GJB2 and 3 families with positive result for mutation in GJB2, were excluded from our study.
With linkage analysis, none of selected families was linked to DFNB35 or DFNB42 loci. This study showed that the ILDR1 and ESRRB mutations have no role in hearing loss in studied families.
This study shows that mutations in ILDR1 and ESRRB genes have no important role in incidence of hearing loss in Khuzestan province. This result suggests that studying of other loci that are involved in deafness, can be helpful to identify genetic causes in this disease in the studied population.

Hearing loss, a sensorineural disorder, is one of the most common congenital impairments, occurring in approximately 1 in 500 newborns. Hearing loss is a highly heterogenic disease and half of the cases of deafness are attributed to genetic causes; environmental and unknown factors account for the remainder. Non-syndromic type forms 70% of hearing loss cases. Pattern of inheritance of nearly 80% of this type of HL is recessive autosomal. Iranian population provides a valuable genetic resource to study this kind of HL because of high ratio of consanguinity. In this study, genetic linkage of DFNB48 (CIB2) and DFNB98 (TSPEAR) is investigated in families with ARNSHL impairment from Khouzestan province.
In this descriptive study 300 individuals of 25 families with hearing loss were examined in order to determine type and frequency of mutation of DFNB48 and DFNB98 loci in Khouzestan province. Familie's selection had some criteria. Families with healthy parents, consanguineous marriage and negative result for mutations of GJB2 gene with at least two affected individuals were selected. 3 families which were detected positive for mutations of GJB2 gene were excluded from study. Linkage analysis was done for 22 families by using six STR markers which were located in or were tightly linked to each locus.
None of these families inspected by linkage analysis was linked to the DFNB48 or DFNB98 loci.
Considering these results it seems that CIB2 and TSPEAR genes mutations have not important roles in hearing loss in Khouzestan province.