P2X7 receptor polymorphisms and susceptibility to tuberculosis in a North Indian Punjabi population.

Background: Genetic elements are known to influence susceptibility to tuberculosis (TB). P2X7R is a candidate gene with multiple single-nucleotide polymorphisms (SNPs) that has the potential to influence an individual's ability to kill the intracellular pathogen Mycobacterium tuberculosis.

Objective: To explore the role of five functional polymorphisms of P2X7R in susceptibility or resistance to TB in a North Indian Punjabi population.

Design: A case-control study was conducted among 245 TB patients (145 pulmonary TB [PTB] and 100 extra-pulmonary TB [EPTB]) and 247 healthy controls. DNA extracted from samples of peripheral blood was analysed for five SNPs of P2X7R using amplification refractory mutation system-polymerase chain reaction (PCR) [-762(T/C), +1513(A/C), DNA sequencing +1729(T/A)] and PCR-restriction fragment length polymorphism [+489(G/A), +946(G/A)] methods.

Results: Of the three loss-in-function polymorphisms, +1513(A/C) showed a statistically significant association with TB susceptibility, while the other two (+946 and +1729) sites were found to be monomorphic in our population. The only gain-in-function polymorphism (+489), and -762 promoter polymorphisms failed to reveal differences in genotypic or allelic distributions.

Conclusion: The C allele at the +1513 site was identified as a risk factor for TB in this North Indian Punjabi population; the +1729 site was found to be monomorphic, unlike its polymorphic distribution in a South Indian TB patient population.