Mutations in several genes segregate with PD in families, including LRRK2 that codes for the kinase Leucine-rich repeat kinase 2.1 The G2019S substitution in the kinase domain of LRRK2 confers increased kinase activity and has been linked to neuronal toxicity.2–4 Thus, targeting the kinase activity of LRRK2 has been proposed as a therapeutic strategy for PD and a number of tool compounds have been developed. The gene discussed is LRRK2; the disease is Parkinson disease.