Abstract

Background: Two important genes for controlling TB are IFN gamma and IFN gamma R1 However, little information exists regarding genetic susceptibility of the Iranian TB population. Methods: We investigated the single nucleotide polymorphisms (SNPs) in genes of IFN gamma (+874 A/T) and IFN gamma R1 (-56 C/T) and serum level of IFN gamma and their influence on TB in patients; 300 patients with TB and 300 healthy controls were enrolled in this study PCR-restriction fragment length polymorphism was used to identify SNPs and serum level of IFN gamma was measured by ELISA. Results: The allelic and the genotypic form of IFN gamma+874 A/T SNP of the studied population were not significant (p>0.05) Allele T frequencies of IFN gamma R1 -56 C/T promoter region in patients with pulmonary TB (PTB) or extrapulmonary TB (EPTB) were significantly greater than allele C The -56 TT motif of IFN gamma R1 is associated with both forms of TB (p<0.05) The serum level of IFN was significantly higher in patients with TB than in controls, but there was no significant difference between serum level of IFN gamma and the studied genotypes (p> 0.05). Conclusions: The cause of active TB in the patients seems to be due to the lack of effective IFN function or the lack of effective signaling connection between IFN and its receptor in presence of -56 C/T polymorphism in promoter region of IFN gamma R1 gene.