GSTT1 and GSTM1 Gene Polymorphisms as Major Risk Factors for Asthma in a North Indian Population

Abstract

According to the National Family Health Survey, asthma is one of the leading diseases in India. In order to understand the complexity of asthma, the susceptibility genes need to be targeted for their association. Glutathione S-transferases play a major role in the detoxification of metabolites of oxidative stress resulting in inflammation and asthma. In the present study, the hypothesis that GSTT1 and GSTM1 gene polymorphisms are associated with asthma was examined. This is the first study to investigate the role of GSTT1 and GSTM1 gene polymorphisms in asthma pathogenesis in a North Indian population. A total of 824 subjects were recruited, of which 410 were asthma patients, including 323 patients suffering from allergic rhinitis. The other 414 recruits were healthy controls from regions of North India. Multiplex PCR was used for genotyping the GSTT1 and GSTM1 gene polymorphisms. The GSTT1 null allele was more prevalent in asthma patients (40%) than in the control subjects (13.3%), which yielded a nearly fourfold risk towards asthma with odds ratio (OR) (95% CI)=4.35 (3.04-6.24), χ(2)=75.34, and p=0.000. The GSTM1 polymorphism also revealed a greater prevalence of the GSTM1 null allele in asthma patients (46.6%) than in controls (39.4%). Statistical analysis yielded a marginal risk toward asthma with OR (95% CI)=1.34 (1.01-1.79), χ(2)=4.37, and p=0.036. Polymorphisms as a result of deletions in the GSTT1 and GSTM1 genes confer an increased risk towards asthma thereby suggesting the protective role of these functional genes in the development of the disease.