PPT1 and Parkinson disease: Then, we verified the robust association of GBA and PD, as well as the suggestive link between different additional susceptible genes and PD in the familial or sporadic early-onset PD cohort (SMPD1, GUSB, CLN6, PPT1, and SCARB2) and sporadic late-onset PD cohort (GALNS and NAGA).