Arg677Trp and Arg753Gln Polymorphisms in TLR2 Genes Detected in Patients With Tuberculosis in Golestan Province, Iran

Abstract

Introduction: Toll-like receptors (TLRs), especially TLR2, play an important role in the immune responses of patients with tuberculosis (TB). The prevalence of TB is estimated 38.15 per 100,000 population in Golestan Province, Iran, which is higher than the rates reported in other provinces. Objectives: The current study aimed at detecting Arg677Trp and Arg753Gln polymorphisms in TLR2 genes detected in patients with TB in Golestan province. Methods: A total of 130 blood samples were collected from patients with sputum smear-positive TB, and 130 blood samples were collected from healthy individuals. Two polymorphisms of TLR2 gene, i e, Arg677Trp and Arg753Gln, were investigated via polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) and sequencing methods. Results: History of corticosteroid use was more frequently reported in patients, compared to the controls, while the frequency of Bacillus calmette-guerin (BCG) vaccination was more reported in controls. PCR-SSCP analysis of the TLR2 Arg677Trp region showed an almost identical pattern for patients and controls, while 2 SSCP patterns were observed in the amplicon, related to the Arg753Gln polymorphism. DNA sequencing for the Arg677Trp polymorphism showed a duplicated pseudogene, similar to the mutant sequence (C > T), as this polymorphism cannot be considered conclusive. The Arg753Gln polymorphism was not found in the samples, although nucleotide deletion (G) was detected at position 808 among the patients. Conclusions: The Arg753Gln polymorphism was not involved in susceptibility to TB in the current study population. The presence of pseudogenes in some genes such as TLR2 necessitates careful interpretation of such studies.