GBA1 and Parkinson disease: Since α-syn is mainly degraded by the lysosomal-autophagic pathway and combined with our previous study that showed lysosome function was decreased in an LBD model and patients; and that the mutation of GBA, which encodes a lysosomal enzyme involved in sphingolipid degradation, is the single greatest risk factor for PD and LBD38,39; and LBD patients have 6 to 8 times higher risk as a carrier with GBA mutant44; we were prompted to further investigate lysosome function.