For example, perturbations in PTEN induced kinase 1 (PINK1) (4), Parkin RBR E3 ubiquitin protein ligase (parkin) (5), glucosylceramidase β 1 (GBA) (6), and leucine rich repeat kinase 2 (LRRK2) (7) have each been discovered to be major genetic risk factors for the development of PD. This evidence concerns the gene LRRK2 and Parkinson disease.