When comparing clinically typical dominant (PARK-SNCA, PARK-LRRK2, PARK-VPS35)1 and recessive (PARK-Parkin, PARK-PINK1, and PARK-DJ1)2 forms of monogenic PD with the atypical forms investigated here, the AAO was lowest overall in the recessive atypical group, with a median AAO of 16 years, followed by the recessive typical forms (31 years), the dominant atypical (49 years) and the dominant typical (55 years) forms and is highest in patients with nonmonogenic atypical parkinsonism (64 years). The gene discussed is LRRK2; the disease is Parkinson disease.