LRRK2 and Parkinson disease: In some populations, particularly Ashkenazi Jewish and Berber Arab populations, mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are found in a significant proportion of individuals with PD, and theLRRK2 prodrome and established PD phenotypes, as well as the pathology, may differ from “idiopathic” PD43–48.