and gene polymorphism-a possible association with drug-resistant tuberculosis in the north Indian population.

Objectives: The objective of this study is to analyze the association between and gene polymorphism with drug resistant tuberculosis (PTB, MDR-TB, and XDR-TB) in a population from Agra, Uttar Pradesh.

Methods: The present case-control study included 101 pulmonary TB patients, 104 multidrug-resistant TB patients, 48 extremely drug-resistant TB patients, and 130 healthy and unrelated controls residing in the same locality. The genotyping method for was carried out by allele-specific polymerase chain reaction (PCR), and gene polymorphism was performed by hybridization probe chemistry in Roche Real-Time PCR. Genotype and allele frequencies were analyzed by the chi-square test. Cytokine levels were measured by ELISA and compared using Mann-Whitney and Kruskal-Wallis tests.

Results: The frequency of heterozygous () genotypes for polymorphism was predominant in XDR-TB patients (0.57), whereas heterozygous A/G genotype for single nucleotide polymorphism (SNP) was predominant in healthy controls (0.57) for gene polymorphism. The heterozygous genotype of polymorphism was found to be significantly higher in XDR-TB ( = 0.0001). SNP, AG genotypes were found to be significantly associated with healthy controls than PTB ( = 0.047). The level of serum cytokines (IL-6, TNF-α, and IFN-γ) was also found to be significantly different among TB patients and healthy controls.

Conclusion: The findings suggested that in the present population, the heterozygous () genotype and deletion allele of polymorphism are associated with the risk for the development of drug-resistant TB. Furthermore, for gene polymorphism, A/G genotype, and G allele are found associated with healthy controls, suggesting the protective role against TB.