Although our findings emphasize a possible vulnerability of developing PD in those carrying the VPS35 A320V variant, our observation may be biased as functional studies were performed after overexpression of the wild-type or A320V VPS35 and SNCA, and the observed effects could be rather divergent from effects caused by endogenous physiological expression levels of VPS35 or SNCA. This evidence concerns the gene VPS35 and Parkinson disease.