Association of microRNA-125a and microRNA-499a polymorphisms in chronic periodontitis in a sample south Indian population: A hospital-based genetic association study.

Periodontitis is a chronic inflammatory disease, caused by interaction between periodontopathic bacteria and the host immune response. MicroRNAs are small, single-stranded molecules, which play a key role in the regulation of diverse biological processes. Dysregulation of microRNAs function can lead to several diseases such as autoimmune and chronic inflammatory diseases. The objective of the study was to determine the association between selected single nucleotide polymorphisms in miR-125a, miR-499 and LIN28 homology A with chronic periodontitis susceptibility in a sample population from south India. Genotyping of the single nucleotide polymorphisms in miR-125a (rs41275794, rs12976445, rs10404453 and rs12975333), miR-499 (rs3746444) and LIN28 homolog A (rs3811463) was performed in DNA from288 controls (individuals with healthy gingiva) and 262 cases (chronic periodontitis patients) by direct dye-terminator sequencing. Disease association analysis revealed a significant association of the variant alleles of the miR-499a polymorphism (rs3746444) in chronic periodontitis [OR=2.07; 95%CI (1.35-3.17)]. The risk associated C-allele frequency was found to be higher in chronic periodontitis subjects as compared to that of healthy individuals. Similar results were also observed in the dominant model [OR=2.42; 95% CI (1.67-3.51)]. The recessive model for miR-125a polymorphism (rs12976445) was also found to be statistically significant with OR=1.54 and 95% CI (1.03-2.30). The haplotype "GCGGCA" was found to be higher in chronic periodontitis subjects than in healthy individuals. Pairwise linkage disequilibrium analysis exhibited that the polymorphisms, rs41275794 and rs12976445 in miR-125a, were in strong linkage equilibrium (D'=0.97). Epistatic interaction by multifactorial dimensionality reduction analysis revealed that the genotypes of the polymorphisms of miR-125a (rs41275794, rs12976445, rs10404453), miR-499a (rs3746444) and LIN28 (rs3811463) were interacting significantly [OR=2.54 (1.65-3.92)], thereby contributing to the risk of chronic periodontitis.