We also found microsomal Epoxide hydrolase 1 (EPHX1) to have a role during xenobiotic detoxification of exogenous chemicals (tobacco smoke) [32], and Glutathione S transferase (GSTA4), an enzyme of the glutathione metabolism, already described to be altered in influenza virus and respiratory syncytial virus infections [33]. This evidence concerns the gene GSTA4 and respiratory syncytial virus infectious disease.