ABSENCE OF MUTATIONS IN SUPEROXIDE-DISMUTASE AND CATALASE GENES IN PATIENTS WITH PARKINSONS-DISEASE

Background: Parkinson's disease (PD) is an adult-onset, neurodegenerat ive disorder characterized by a selective loss of the dopaminergic cel ls of the substantia nigra and by progressive motor decline. Studies h ave shown aberrant oxidative stress metabolism within the substantia n igra and other dopaminergic regions of the brain in patients with PD. Objective: 70 screen the genes of three free radical detoxifying enzym es-copper/zinc superoxide dismutase, manganese superoxide dismutase, a nd catalase-for mutations in patients with PD. Patients and Methods: A total of 107 unrelated patients with PD from two PD populations (fami lial and sporadic) were screened for mutations in the genes of copper/ zinc superoxide dismutase, manganese superoxide dismutase, and catalas e by single-strand conformation analysis. The diagnosis of PD was base d on the clinical observations of resting tremor, rigidity, and bradyk inesia. Results: No mutations were identified. However, we did identif y an amino acid substitution (glycine to aspartic acid) in exon 9 of t he catalase gene in one patient; decreased red blood cell catalase act ivity was observed in this patient. Conclusion: Parkinson's disease is not caused by mutations in the genes of these three detoxifying enzym es. The exon 9 variant in the catalase gene in the one family with PD is most likely a silent mutation and not the genetic cause of PD in th is family.