Complex phenotypes in an Indian family with homozygous SCA2 mutations.

We describe a consanguineous Indian family having spinocerebellar ataxia type 2 (SCA2) expansions with complex phenotypes (early-onset, dopa-responsive parkinsonism, ataxia and retinitis pigmentosa). The two probands having homozygous SCA2 mutations presenting with early-onset dopa-responsive parkinsonism without ataxia develop dyskinesias within a year of starting levodopa. Their siblings, heterozygous for SCA2 mutations, had retinitis pigmentosa with or without ataxia. Approximately 38% of family members with SCA2 mutations were asymptomatic.