Mean (SD) superoxide-dismutase (SOD), glutathione-peroxidase (GPx), and catalase activities (expressed as units/mg protein); and concentrations of coenzyme Q10 (expressed in nmol/g protein) in skin fibroblast cultures of patients with Parkinson's disease (PD) and controls (CS = citrate synthase). This evidence concerns the gene CAT and Parkinson disease.