Relationship of Age of Onset and Family History in Parkinson Disease

BackgroundThe aim of this study was to determine whether age of onset of Parkinson disease (PD) is associated with differences in PD risk and PD age of onset in parents and siblings. MethodsClinical and detailed family history data were available for 1,114 PD probands. ResultsProband age of onset was not associated with differences in PD prevalence or PD age of onset in parents. Proband age of PD onset <50, compared with 50 years, was associated with significantly greater risk of PD in siblings (hazard ratio: 2.4; P=0.002; 95% confidence interval: 1.4, 4.1), and proband age of onset was significantly correlated with sibling age of onset (Somer's D=0.20; P=0.018). ConclusionsProband age of PD onset is not associated with differences in parental PD risk. Siblings of PD patients with onset before age 50 are at increased risk of PD and are more likely to have early-onset disease. (c) 2014 International Parkinson and Movement Disorder Society