Analysis of major otosclerosis-associated variants in RELN and TGFB1 genes in Polish patients

Introduction: Otosclerosis (OTSC) is one of the most common causes of progressive adult-onset hearing loss in the Caucasian population, with a female preponderance. The etiology of OTSC is complex and there are a number of genetic variants reported to be associated with OTSC susceptibility, but no data on the genetic background of OTSC in patients originating from the central-eastern part of Europe have been available. The purpose of our study was to investigate in Polish patients the frequency of genetic variants previously reported to be most strongly associated with OTSC. Material and methods: Genomic DNA was isolated from blood samples or buccal swabs. Variants in TGFB1 (rs1800472) and RELN (rs39335, rs39350, rs39374) were genotyped in surgically confirmed OTSC patients (n = 94) and a control group (n = 198) using custom TaqMan SNP genotyping assays and real-time PCR. Allele and genotype frequencies were compared between the groups in statistical analysis and the odds ratios with 95% confidence intervals were calculated to estimate the risk. Results: For all of the tested variants the distributions of alleles and genotypes were not statistically significantly different between OTCS patients and the control group. There were also no statistically significant differences in relation to gender of the tested subjects. Conclusions: Despite multiple confirmatory studies on TGFB1 and RELN association with OTSC development in some populations, no significant association between the studied variants and OTSC was found in Polish patients. Our results indicate the presence of inter-population differences in OTSC susceptibility factors and confirm the large genetic heterogeneity of this disorder.