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Among the families with early-onset Parkinson's disease, 36 (49 percent) had parkin mutations. The age at onset ranged from 7 to 58 years. Among the patients with isolated Parkinson's disease, mutations were detected in 10 of 33 patients (77 percent) with an age at onset of 20 years or younger, but in only 2 of 64 patients (3 percent) with an age at onset of more than 30 years. The mean (+/=SD) age at onset in the patients with parkin mutations was younger than that in those without mutations (32+/=11 vs. 42+/=11 years, P<0.001), and they were more likely to have symmetric involvement and dystonia at onset, to have hyperreflexia at onset or later, to have a good response to levodopa therapy, and to have levodopa-induced dyskinesias during treatment. Nineteen different rearrangements of exons (deletions and multiplications) and 16 different point mutations were detected. Mutations in the parkin gene are a major cause of early-onset autosomal recessive familial Parkinson's disease and isolated juvenile-onset Parkinson's disease (at or before the age of 20 yeaers). Accurate diagnosis of these cases cannot be based only on the clinical manifestations of the disease. |
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