Exposure to biomass smoke, cigarettes, and alcohol modifies the association between tumour necrosis factor (–308G/A, –238G/A) polymorphisms and tuberculosis in Mexican carriers

INTRODUCTION: Exposure to biomass smoke, cigarettes, alcohol, and the impairment of immunoregulation are considered to be risk factors for tuberculosis. Tumour necrosis factor (TNF) –308G/A and –238G/A gene polymorphisms have been associated with tuberculosis. However, the results remain inconsistent. The aim of this study was to determine the association between TNF polymorphisms and tuberculosis in the presence of biomass smoke, cigarettes, and alcohol in a Mexican population. MATERIAL AND METHODS: TNF polymorphisms were determined in 118 tuberculosis patients and 223 controls. We performed a univariate, bivariate, stratified analysis. Odds ratios, confidence intervals, and p-values were calculated. RESULTS: Occupational biomass smoke exposure was associated with tuberculosis between the patients and controls (OR = 1.70, 95% CI: 1.08–2.70, p = 0.02). We also found an association of the –308A allele carriers between the patients and controls without exposure to occupational (p = 0.04, OR = 0.16, 95% CI: 0.01–0.92) and in-home (p = 0.02, OR = 0.14, 95% CI: 0.01–0.81) biomass smoke, as well as an association with alcohol (p = 0.01, OR = 0.24, 95% CI: 0.05–0.75). The haplotype analysis revealed an association of the –308A/–238G haplotype between patients and nonconsanguineous controls without exposure to occupational (p = 0.02, OR = 0.12, 95% CI: 0.01–0.99) and in-home (p = 0.01, OR = 0.1, 95% CI: 0.01–0.9) biomass smoke, cigarette use (p = 0.04, OR = 0.28, 95% CI: 0.08–0.98), and alcohol (p = 0.02, OR = 0.22, 95% CI: 0.05–0.88) intake. CONCLUSIONS: The TNF –308A allele and the –308A/–238G haplotype are associated with tuberculosis, as are exposure to biomass smoke, cigarettes, and alcohol. No association for the –238G/A polymorphism was found. Our results provide insight into a possible protective role of TNF polymorphisms in tuberculosis in our population.