LRRK2 and Parkinson disease: ,7 Importantly, all PD-associated mutations activate leucine-rich repeat kinase 2 (LRRK2) kinase activity, offering a promising therapeutic target for PD by inhibiting this function.7, 8, 9 Better understanding of LRRK2-PD pathophysiology and discovery of related biomarkers would facilitate LRRK2-targeted therapies.