VPS35 and Parkinson disease: Restricting the analysis to just the extreme right tail of the GenePy distribution for each of the six PD genes, statistically significant differences were observed between PD and non-PD individuals for LRRK2 (p = 0.002), PINK1 (p = 0.010), PRKN (p = 0.021) and VPS35 (p = 0.036).