The endolysosomal pathway is implicated in α-synuclein accumulation and degeneration of dopaminergic neurons, in which a variety of genes observed in monogenic variants of PD or hereditary risk factors for the disease are involved, such as ATP13A2, SNCA, PINK-1, PARK, and LRRK2. GCase forms a complex together with membrane-bound α-synuclein, which decreases its activity. This evidence concerns the gene PINK1 and Parkinson disease.