TLR2 polymorphisms, Arg753Gln and Arg677Trp, are not associated with increased burden of tuberculosis in Indian patients

BACKGROUND: In view of the role of TLR2 activation in host defense against mycobacteria, the present study was conducted to examine whether TLR2 polymorphisms could account for the increased prevalence of tuberculosis in Indian patients. Detection of such polymorphisms would help in assessing the risk of developing active tuberculosis among contacts or HIV positive patients and in identifying candidates for chemoprophylaxis. FINDINGS: One hundred patients with tuberculosis and 100 controls were investigated for the presence of two TLR2 polymorphisms, viz. Arg753Gln and Arg677Trp, using PCR-RFLP of a 340 bp region of the TLR2 gene, followed by DNA sequencing of a randomly selected group of 35 patients. While these polymorphisms were found to be non-existent in our study groups, we observed a novel polymorphism Phe749Tyr in 2 patients. However, this polymorphism was associated with negligible deviation in Delphi electrostatic potential and structural alignment from the wild-type TLR2 protein, making it an unlikely candidate for any significant structural or functional alteration at the protein level. CONCLUSION: Hence we conclude that, contrary to reported associations in other populations, TLR2 polymorphisms are not responsible for the increased prevalence of TB in the Indian population.