With respect to PD, it was revealed that with increasing age there is a decrease in superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) in the substantia nigra (SN) but there was no change in GPx and GR in the caudate nucleus with increasing age [18], [29]. The gene discussed is SOD1; the disease is Parkinson disease.