Other SNP-based genomic studies tested associations of Polygenic Risk Scores (PRS) for PD with alpha-synuclein levels in the cerebrospinal fluid, age-at-onset of the disease, motor/cognitive symptoms and PD status [as reviewed in (28)], detecting significant associations with PD risk (29), earlier PD onset (29, 30), and faster motor and cognitive decline (31). This evidence concerns the gene SNCA and Parkinson disease.