Association of interleukin 7 receptor (rs1494555 and rs6897932) gene polymorphisms with asthma in a north Indian population

BACKGROUND Interleukin 7R (IL-7R), a cytokine receptor gene, plays an important role in the development of innate and adaptive inflammatory response in asthma etiology. OBJECTIVE IL-7R is a heterodimeric protein composed of α chain and γ chain. The α chain of IL-7R has a range of single nucleotide polymorphisms, which give rise to nonsynonymous amino-acid substitutions that might result in an increased production of inflammatory cytokines and cause asthma. METHODS A case-control study was conducted with a total of 964 subjects, including 483 healthy controls and 481 patients with asthma. DNA samples were extracted from blood, and genotyping was done by using sequence-specific-primer-polymerase chain reaction. RESULTS Statistical analysis revealed that IL-7R + 1237A/G (rs1494555) gene polymorphism shows a highly protective association toward asthma (odds ratio [OR] 0.56, p < 0.001) in AG genotype as well as in mutant GG genotype (OR 0.64, p = 0.029). However, IL-7R + 2087T/C (rs6897932) polymorphism showed an increased risk toward asthma in TC genotype (OR 1.70, p = 0.002) as well as in the CC genotype (OR 1.68, p = 0.002). Furthermore, the GT and AC haplotypes in the IL-7R polymorphisms were also found to be significantly associated with asthma (p < 0.001 and p = 0.037, respectively). CONCLUSIONS The study conducted in a north Indian population indicated that the protective association was observed for the +1237A/G position, and a significant risk was observed for the +2087T/C position in asthma.