PPT1 and Parkinson disease: Among the WES cohort with familial PD or sporadic early-onset patients with PD, except for the established GBA (P = 1.58E-22), the rare putative damaging variant category of additional genes also shown suggestively significant difference between cases and controls, including the potential susceptibility gene SMPD1 (P = 0.015), as well as other four novel genes: GUSB (P = 0.003), CLN6 (P = 0.015), PPT1 (P = 0.022), and SCARB2 (P = 0.034) (Table 3).