An alteration in transcriptional activity of various pathways such as nuclear factor erythroid 2-related factor 2 (Nrf2), glycogen synthase kinase 3β (GSK-3β), nuclear factor kappa B (NF-κB), and reduced activity of superoxide dismutase (SOD), catalase and glutathione (GSH) occurs with aging, which may be correlated with the increased incidence of PD (Figure 2). The gene discussed is CAT; the disease is Parkinson disease.