Association of G-308A TNF-alpha polymorphism with bronchial asthma in a North Indian population

Bronchial asthma is an inflammatory disorder in which genetic and environmental factors play an important role. Several susceptible genes have been identified using whole genome scan and candidate gene approaches. Tumor necrosis factor alpha, a pro-inflammatory cytokine, is one such gene that figures prominently in such investigations. The secreted levels of this cytokine are under genetic control and attributed to the presence of single nucleotide polymorphism G-308 A in the promoter region of its gene. However, the association of this polymorphism varies from population to population. As there are no data available on North Indians, the present study aims to fill this void. For this, 366 subjects (155 asthmatic and 211 normal control subject) were genotyped using Amplification Refractory Mutation System Analysis (ARMS-PCR) and agarose gel electrophoresis. The distribution of G/A alleles between the two groups revealed statistically significant differences (p = 0.016). Furthermore, the asthma patients categorized on the basis of pattern (Seasonal versus Perennial) and age of onset of disease (Childhood versus Late Onset) revealed significant association with only seasonal (p = 0.021) and late onset asthmatic groups (p = 0.039). The data from the present study strongly suggest an association between TNF-alpha and asthma in the North Indian population.