LRRK2 and Parkinson disease: In order to investigate the roles of LRRK2, and mutated LRRK2, in the development of Parkinsonism, several rodent models bearing the G2019S mutation have been generated using, for example, bacterial artificial chromosome (BAC) and knock-in (KI) to express human or murine LRRK2 or LRRK2-G2019S [9,10,11,12,13,14,15].