TLR5 Polymorphisms rs2072493, rs5744174, and rs5744168 Are Not Genetic Risk Factors for Chronic Helicobacter pylori Infection in Indian Tamils.

The incidence of Helicobacter pylori (H. pylori) infection and gastric cancer is on the rise in India, and the genetic factors influencing the increased susceptibility in Indian population remain obscure. Toll-like receptors (TLRs) play a major role in innate immune system and genetic polymorphisms affecting their function were reported to enhance the risk for H. pylori infection. Seventy-seven patients (n = 77) diagnosed with H. pylori infection and 230 healthy subjects were recruited in this study. The rs2072493, rs5744174, and rs5744168 polymorphisms within TLR5 gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Tetra-ARMS PCR genotyping techniques. Present study revealed that these studied polymorphisms are less frequent in south Indian Tamils and thus failed to confer a significant risk to develop chronic H. pylori infections. The distribution of ancestral allele of rs2072493 polymorphism conferred resistance to develop chronic H. pylori infection in our population (p = 0.024; OR  =  0.53; 95% CI: 0.3-0.91). The lesser incidence of polymorphic alleles suggests that the TLR5 gene is under genetic selection pressure to withstand the prevailing endemic infections among south Indian Tamils.