Clinical trials have been completed or are currently underway to evaluate venglustat, an orally available, highly selective, brain-penetrant, small molecule GCS inhibitor, in several patient populations including chronic neuronopathic Gaucher disease (Gaucher disease type 3; NCT02843035), Fabry disease (NCT02228460), GM2 gangliosidosis (NCT04221451), autosomal-dominant polycystic kidney disease (NCT04705051), and early stage PD patients harboring heterozygous GBA mutations (NCT02906020), as a potential disease-modifying therapeutic. This evidence concerns the gene GBA1 and Parkinson disease.