GBA1 and Parkinson disease: The Parkinson's disease-associated cluster of proteins implicated in the endo-lysosomal system includes the lysosomal β-glucosylceramidase (encoded by GBA1), the lysosomal polyamine exporter ATP13A2 [97], the endoplasmic reticulum (ER)-to-lysosome lipid transfer protein VPS13C [98,99], the lysosomal proton channel TMEM175 [100] and VPS35, which is part of the retromer complex involved in endo-lysosomal sorting of proteins (table 1 and figure 1).