Genetic Variation of D7S2420 Marker in Five Ethnic Groups of the Iranian Population: A Highly Informative Marker for Molecular Diagnosis of ARNSHL Print

SLC26A4 gene mutations are the second currently identifiable genetic cause of autosomal recessive non-syndromic hearing loss (ARNSHL) after GJB2 mutations, which are nowadays being investigated in molecular diagnosis. In databases, several potential STR markers related to this region have been introduced. In this study, the identity and informativeness of D7S2420 CA repeat STR marker in 5 end of SLC26A4 gene region was examined in five ethnic groups of the Iranian population. The locus was genotyped in 165 unrelated healthy individuals of five different ethnics including Fars, Azari, Turkmen, Gilaki, and Arabs using polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis (PAGE) and fluorescent capillary electrophoresis. In the present study, the results of fluorescent capillary electrophoresis were analyzed by GeneMarker HID Human STR Identity software. The allele frequency, degree of heterozygosity and Hardy-Weinberg equilibrium (HWE) for unrelated individuals were estimated with the GenePop program and polymorphism information content (PIC) values were computed by Microsatellite Tools software. Analysis of the allelic frequency revealed the presence of 11 alleles for D7S2420 marker in the Iranian population of which, the allele 288bp at the D7S2420 locus with 24% frequency was the most frequent. The observed heterozygosity in all investigated ethnic groups was above 70%, with the highest rate of 87.9% for the Fars ethnic origin. Analysis of deviations from Hardy-Weinberg equilibrium demonstrated that all the ethnic groups were in equilibrium (P>0.05) for the D7S2420 locus. Finally, analysis of PIC value revealed that the D7S2420 marker could be considered as a highly informative marker in each ethnicity of the Iranian population (PIC value above 0.7). Our data suggested that D7S2420 could be introduced as a highly informative marker in molecular diagnosis of SLC26A4 based ARNSHL in our population by linkage analysis.