Variants in the proinflammatory cytokine gene tumor necrosis factor α [TNFA, GeneID 7124 (Entrez Gene 2008)] have been linked to decrease in pulmonary function (Winterton et al. 2001; Yang et al. 2005) and asthma and wheezing (Li et al. 2006) in relation to O3 and sulfur dioxide exposure. The gene discussed is TNF; the disease is asthma.