Background: Toll-like receptors (TLRs) act as mediators of an innate immune response to infectious agents. The risk for chronic infection and the development of cancer can be potentially influenced by the genetic variations in the TLR genes. TLR3 and TLR7 genes have been associated with susceptibility to several infections and immune diseases. Human populations are very diverse. There are significant variations in the TLR3 and TLR7 polymorphisms among ethnic groups. Variations within the population are associated with the disease outcome. Hence, we aimed to compare the occurrence of TLR3 (rs5743312 C/T, rs3775296 C/A, and rs3775291 C/T) and TLR7 (rs179009 and rs179008) polymorphisms among healthy individuals of various populations.
Methods: Genotyping of TLR3 (rs5743312 C/T, rs3775296 C/A, and rs3775291 C/T) and TLR7 (rs179009 and rs179008) polymorphisms were done in 158 healthy controls from the Western India by utilization of PCR-RFLP.
Results: In our study population, the prevalence of TLR3 rs5743312 CC, CT, and TT genotypes were found to be 67.1%, 31.0%, and 1.9%, respectively, whereas genotype distribution of rs3775296 C/A polymorphism was 65.2%, 31.6%, and 3.2%, respectively and rs3775291C/T was 59.5%, 32.3% and 8.2%, respectively. The occurrence of TLR7 rs179008AA, rs179008AT, rs179008TT genotypes and rs179008A, rs179008T alleles in the healthy individuals was found to be 81.0%, 16.5%, 2.5% and 89.24%, 10.75%, respectively. The prevalence of TLR7 rs179009AA, rs179009AG, rs179009GG genotypes and rs179009A, rs179009G alleles in healthy individuals was 63.3%, 29.1%, 7.6% and 63.3%, 36.7%, respectively. The frequency of TLR7 polymorphism was compared with Italian, Asian, European, African, German and France populations. The frequency of TLR3 polymorphism was compared with Asians, Caucasians, Taiwanese, Caucasians and Saudi Arabians, Poland, Taiwanese, Italy, Taiwan, Estonia, Asia and Caucasus. The inter-population differences were observed in the distribution of TLR3 and TLR7 polymorphisms.
Conclusion: The prevalence of TLR3 and TLR7 polymorphisms suggested that genotype-phenotype studies should be conducted among populations to address the innate immune responses against pathogens.