GBA1 and Parkinson disease: In this article, we first summarize the current knowledge about the mechanisms of α-synuclein degradation in lysosomes, and then focus on the roles of other well-analyzed PD gene products, namely LRRK2, VPS35, ATP13A2 and GBA, in terms of their individual and co-operative regulations of endolysosomes and α-synuclein dynamics.