Background: SLC26A4 gene mutations are the second currently identifiable genetic cause of autosomal recessive non syndromic hearing loss (ARNSHL) after GJB2 mutations. In databases, several potential STR markers related to this region have been introduced. In this investigation, the identity and informativeness of D7S2459 CA repeat STR marker in SLC26A4 gene region was examined in five ethnic groups of the Iranian population.

Materials and Methods: The research study was accomplished by genotyping the locus in 165 individuals of five different ethnic groups including Fars, Azari, Torkaman, Gilak and Arab using polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and fluorescent capillary electrophoresis. In this study, results were analyzed by GeneMarker HID Human STR Identity software, GenePop program and Microsatellite Tools software.

Results: Analysis of the allelic frequency revealed the presence of 8 alleles for D7S2459 marker in the Iranian population. Among all, allele 148bp at the D7S2459 locus with 31% frequency was the most frequent. The Azari ethnic with 84.8% observed heterozygosity was the highest among all ethnic groups. Finally, analysis of PIC value revealed that D7S2459 marker could be considered as a highly informative marker in each ethnic of the Iranian population (PIC value above 0.7).

Conclusion: Our data suggested that D7S2459 could be introduced as a highly informative marker in molecular diagnosis of SLC26A4 based ARNSHL by Linkage analysis.

Background: Niemann-Pick disease (NPD) refers to a group of lysosomal storage diseases that causes abnormal metabolism of lipids. One of the genes that play a role in the pathogenesis of this disease is SMPD1. To date, more than hundred disease- causing mutations have been identified in SMPD1 gene. Due to the large number of mutations in this gene, direct analysis of the mutations is costly and time-consuming. Therefore, indirect linkage analysis using polymorphic markers as an alternative method for molecular diagnosis of the mutations has been recommended. In the present study, allele frequency of rs1542705 genetic marker was analyzed in the Iranian population. The aim was to determine the polymorphic information content (PIC) and the possibility of its application in indirect diagnosing of NPD.

Materials and Methods: After bioinformatics analysis of the SMPD1 gene region, rs1542705 marker was selected for genotyping in Isfahan population. In order to calculate the allele and genotype frequency of the marker, molecular tests were done on 113 DNA samples of unrelated healthy individuals by using ARMS-PCR technique. Finally, the information related to the genotype of the individuals was statistically analyzed using Powermarker and Genepop software.

Results: The analyses showed that the studied population was in accordance with Hardy-Weinberg equilibrium. Allele frequency of rs1542705 marker for T and C alleles was 71.24% and 28.76%, respectively, and the heterozygosity of the marker was 43.36%. Also, polymorphic information content (PIC) was 0.325.

Conclusion: The results of this study showed that rs1542705 marker could be considered as an informative marker for molecular diagnosis of Niemann- Pick disease using linkage analysis in the studied population.