Background & Objectives: It is estimated that one third of the world’s population is infected by M. tuberculosis. Because of differences in immune system activity against the invasive microorganisms, the disease is developed only among 10% of them. Vitamin D metabolism and its receptor activity are important factors in human native immune system against tuberculosis. In the present study we investigated ApaI polymorphism of vitamin D receptor (VDR) gene and association with susceptibility to tuberculosis.

  Method: This study was performed on 84 cases with tuberclosis (male =50, female =34) and 90 controls (male =49, female = 41). DNA was extracted from cases and controls leucocytes and elected sequences amplified in polymerase chain reaction (PCR) procedure by using specific primers. ApaI polymorphism of VDR gene evaluated by RFLP technique on PCR products. Finally statistical analysis performed using Chi- square to compare genotype frequencies between cases and controls.

  Results: In case and control groups, AA genotype frequency were 34.5% and 33.3% respectively (OR₌0.905, 95% CI 0.469-1.747, p ₌ 0.766) and a genotype frequency in patients and control group were 15.47% and 13.3% respectively (OR₌0.808, 95% CI 0.333 –1.961, p₌0.637).

  Conclusion: In the present study we could not find any significant relationship between genotype frequency of ApaI (A/a) polymorphism in VDR gene and susceptibility to tuberculosis.