Resendiz-Hernandez JM, et al. - In this case–control study, researchers sought to investigate the genetic differences between COPD patients exposed to smoking and smoke from biomass burning (BB), the two known risk factors of COPD. Herein, the focus was on the possible association of tumor necrosis factor (TNF) promoter polymorphisms. The heterozygous genotype GA of polymorphisms rs1800629 and rs361525 in the TNF promoter were shown to be related to the risk of COPD.