Mitochondrial DNA deletions in Parkinson disease

Introduction. There is growing evidence for the involvement of oxidative chain respiratory in Parkinson disease (PD), suggesting a possible role, genetically or environmentally determined, of mitochondria in both etiology and pathogenesis of the disease. Case reports. We describe two cases of PD in two different pedigrees characterized by diverse phenotypic expression of mitochondrial disease. The first, a 45-year-old man, came for observation with PD, liver cirrhosis, and diabetes mellitus. Family history was positive for chronic external ophtalmoplegia, diabetes mellitus, and liver cirrhosis. The second, a 52-year-old man, was affected by PD and multiple symmetric lipomatosis. Both patients were affected by typical PD with predominant rigid-akinetic symptomatology. The first patient was under treatment with levodopa, complicated by motor fluctuations and dyskinesias. The second one, treated by levodopa and ropinirol, showed stable response to levodopa. Muscle biopsy revealed scattered ragged red fibers and cytochrome C oxidase-negative fibers in both cases, while Southern blot analysis showed multiple mitochondrial DNA deletions in skeletal muscle of the first, and a single deletion in the second one. Conclusions. Our data support the hypothesis that mitochondrial involvement can be a significant contributor to nigral neuronal death in PD.