LRRK2 and Parkinson disease: The G2019S variant, the most common LRRK2 pathogenic mutation in the western world, has a prevalence of 1% in all PD cases worldwide and is extremely frequent in Berber Arabs (up to 37% of PD patients) and Ashkenazi Jews (up to 23% of PD patients) [47,67,68,69,70,71].