On the other several mutations in antioxidant genes, such as GSTP1, glutathione S-transferase (GST) M1, superoxide dismutase 3 (SOD3) and microsomal epoxy hydrolase (EPHX1) is associated with the severity of COPD infection, and the function of the proteins encoded by these genes was impaired, therefore breaking the steady-state of the oxidation-reduction system and increasing the susceptibility to bacterial infections (40). The gene discussed is SOD3; the disease is bacterial infectious disease.