Dominantly-inherited mutations in leucine-rich repeat kinase 2 (LRRK2 p.N1437H, p.R1441C/G/H, p.Y1699C, p.G2019S and p.I2020T)3–6 and vacuolar protein sorting 35 (VPS35 p.D620N)7,8 have been genetically linked to parkinsonism that is clinically and pathologically indistinguishable from idiopathic PD2. The gene discussed is LRRK2; the disease is Parkinson disease.