Several PD risk genes implicated by Genome-Wide Association Studies (GWAS) also have roles at the synapse including (but not limited to) SH3GL2, SYNJ1, RIMS1, VAMP4, SYT4, ANK2, LRRK2, SNCA, STX1B, SYT11, and VPS35 (Nalls et al., 2014, 2019; Chang et al., 2017; Blauwendraat et al., 2020; Grenn et al., 2020). This evidence concerns the gene SNCA and Parkinson disease.