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.