SCA2 may present as levodopa-responsive parkinsonism

Some kindreds with familial parkinsonism exhibit genetic anticipation, suggesting possible involvement of trinucleotide repeat expansion. Recent reports have shown trinucleotide repeat expansions in the spinocerebellar ataxia 2 (SCA2) gene in patients with levodopa-responsive parkinsonism. We tested 136 unrelated patients with familial parkinsonism for SCA2 mutations. Two probands had borderline mutations; the rest were normal. (≤31 repeats is normal, 32-35 is borderline, ≥36 is pathogenic). The expanded allele segregated with neurological signs in one kindred. The absence of borderline mutations in the normal population, and the co-segregation of the expanded allele with neurological signs in one kindred suggest that SCA2 mutations may be responsible for a subset of familial parkinsonism.