Familial aggregation in atypical Parkinson's disease: a case control study in multiple system atrophy and progressive supranuclear palsy.

Familial aggregation has been consistently found in PD, but it is unclear whether there is a familial aggregation in families of patients with multiple system atrophy (MSA) or progressive supranuclear palsy (PSP). MSA and PSP cases were recruited from a two-arm case control study. One control was matched to each case for age, gender and living area. Medical history of first-degree relatives was obtained through a face-to-face questionnaire. Age-specific cumulative incidence of Parkinsonism and dementia in first-degree relatives of cases and controls was compared for MSA and PSP separately. Seventy-one pairs for MSA and their controls and 79 pairs for PSP and their controls were included. No significant familial aggregation was found in PSP. MSA cases reported Parkinsonism more often, but not dementia in their first-degree relatives than controls. MSA patients, but not those with PSP, have Parkinsonism more often in their first-degree relatives than controls.