Investigation of the relationship between polymorphism of IFN-γR1 (-611),IFN-γ(2109) and IL-12B(-1188) genes and pulmonary TB

A large number of factors are involved in the development of TB, but the most important one belongs to the host genetic factors. One of the genetic factors is cytokine gene polymorphisms. The results of recent studies indicate that IL-12 and IFN-γ play a central role in regulating the type and level of immune response in mycobacterial infections. Mutations in these genes may be associated with susceptibility to pulmonary TB. The aim of this study was to investigate the frequencies of IFN- γ (2109), IFN-γ R1 (-611) and IL-12B (-1188) genes polymorphisms and their relationships with susceptibility to pulmonary TB in Iranian population. This was a case-control study. Thirty TB patients with positive smears hospitalized in TB departments of Masih Daneshvari Hospital and 30 healthy controls with no history of TB were selected for this study. Genotypes of IFN- γ (2109), IFN-γ R1 (-611) and IL-12B (-1188) genes were determined by using PCR-RFLP method. The PCR-products were analyzed by use of restriction enzymes. The data were analyzed by means of SPSS and Hardy – Weinberg equilibrium. Considering IFN-γ R1 (-611) and IL-12B (-1188) genes there was a significant difference between the control and study groups (P < 0.05), but in regard to IFN- γ (2109), this difference was not detected between the two groups. Mutation in the regions of -611 of IFN-γ R1 and -1188 of IL-12B genes may increase the host susceptibility to mycobacterium tuberculosis and genotyping of these regions can be used for screening of the high risk individuals.