LRRK2 and Parkinson disease: In 2004, multiple labs identified mutations in the leucine-rich repeat kinase 2 (LRRK2) gene as causative for a dominantly inherited form of PD, leading to an exciting new pathway for researchers to pursue.1, 2 Mutations have also been found in sporadic cases at rates varying from 0.3–41% depending on the country of origin and ethnicity of the population studied.3 Due to similarities in the clinical presentation of LRRK2-associated PD and idiopathic PD,3–5 the study of LRRK2 function has the potential to offer new insight into the mechanisms underlying sporadic PD etiology.