Spinocerebellar ataxia type 2 with parkinsonism in ethnic Chinese

Objective: To describe the clinical and molecular genetic analysis of a lar ge family of northern Chinese descent with a mutation at the SCA2 locus cau sing carbidopa-levodopa-responsive parkinsonism. Background: Most causes of parkinsonism remain unknown. However, molecular genetic analysis of famili es with parkinsonism has recently identified five distinct loci and pathoge nic mutations in four of those. Additionally, some of the spinocerebellar a taxia syndromes (SCA), particularly Machado-Joseph syndrome (SCA3), are kno wn to cause parkinsonism. Spinocerebellar ataxia type 2 (SCA2) has not prev iously been described as causing a typical dopamine-responsive asymmetric P D phenotype. Methods: A large family was evaluated clinically and molecular ly for apparent autosomal dominant parkinsonism. Results: The phenotype inc ludes presentation consistent with typical dopamine-responsive parkinsonism . Other presentations in this family include a parkinsonism/ataxia phenotyp e, which is classic for SCA2 and parkinsonism, resembling progressive supra nuclear palsy. Conclusions: Patients presenting with a family history of pa rkinsonism, including familial progressive supranuclear palsy and PD, shoul d be tested for the spinocerebellar ataxia type 2 expansion.