Risk of Parkinson Disease in Carriers of Parkin Mutations: Estimation Using the Kin-Cohort Method

Results: Parkin mutations were identified in 25 probands with PD (10.1%), 18 (72.0%) of whom were heterozygotes.OneParkinhomozygotewasreportedin2siblings with PD. The cumulative incidence of PD to age 65 years in carrier relatives (age-specific penetrance) was estimated to be 7.0% (95% confidence interval, 0.4%71.9%), compared with 1.7% (95% confidence interval, 0.8%-3.4%)innoncarrierrelativesofthecases(P=.59)and 1.1% (95% confidence interval, 0.3%-3.4%) in relatives of the controls (compared with noncarrier relatives, P=.52). Conclusions:The cumulative risk of PD to age 65 years in a noncarrier relative of a case with an age at onset of 50 years or younger is not significantly greater than the generalpopulationriskamongcontrols.Age-specificpenetrance among Parkin carriers, in particular heterozygotes, deserves further study.