LRRK2 and Parkinson disease: Numerous transgenic animal models have been exploited to study PD, including SNCA (PARK1), parkin RBR E3 ubiquitin protein ligase (PRKN/PARK2/Parkin), PTEN-induced kinase 1 (PINK1/PARK6), parkinsonism-associated deglycase (DJ1/PARK7), and leucine-rich repeat kinase 2 (LRRK2/PARK8).