[Relationship between TNF-alpha gene polymorphisms and susceptibility to pulmonary tuberculosis]

Tuberculosis [TB] caused by Mycobacterium tuberculosis, is an infectious disease in human which kills nearly three millions of people annually. Approximately, one - third of the world populations are infected with this bacteria and 5 - 10% of them develop the active form of the disease. Individuals are different in susceptibility to TB infection. These differences might be due to the host characteristics especially genetic factors. TNF- alpha as a pro-inflammatory cytokine, plays a key role in host defense against tuberculosis. Presence of mutation in this gene can influence the effectiveness, performance and capability of immune responses against TB infection. The Aim of this study was to investigate the frequency of TNF- alpha gene polymorphisms and its relation with susceptibility to the pulmonary TB. Sixty healthy controls and 60 TB patients were enrolled. Genotype of TNF[-238], TNF -244, TNF[-308], TNF[-857] and TNF[-863] were determined using PCR-RFLP method. The results were analyzed by Fisher Exact and kappa[2] tests using SPSS v.14 and evaluated with Hardy-Weinberg equilibrium. The results of this study showed a significant difference in TNF-308 and TNF [-857] regions between the control and study groups [P < 0.05]. Presence of mutation in TNF[-308] and TNF [-857] regions may increase the host susceptibility to mycobacterium tuberculosis and genotyping of these regions can be used for screening of the high risk individuals

[ frequency of vitamin D receptor gene polymorphisms in pulmonary tuberculosis [TB] patients and its relation with susceptibility to TB]

Many genetic studies on predisposing factors for active tuberculosis have been conducted. Study on human leukocyte antigens [HLA], vitamin D receptor [VDR], NRAMP1, mannose binding lectin [MBL], and tumor necrotizing factor [TNF] are the most studies in this field. This study was planned to identify any relationship between VDR polymorphisms [Apa I, Bsm I, Fok I and Taq I] and susceptibility to TB. This case-control study was performed on blood samples from tuberculosis cases [n=164] and controls [n=50]. DNA was extracted from white blood cells and the sequences were amplified by PCR followed by restriction digestion [PCR-RFLP technique] using specific primers and enzymes for each polymorphism. VDR polymorphisms were evaluated for two mentioned groups. Two genotypes of AbfT and AabbFfTT were the only statistically significant genotypes which had adfferent frequency between the study and control groups. Results of this study showed that genotypes of AbfT and AabbFfTT are protective factors against TB in our patients. We could not find any genotype as a predisposing factor for TB in our study group. However, other studies with larger group of samples are needed to find such a relationship