SNCA and Parkinson disease: PD is a non-monogenic disease caused by different genes, such as alpha-synuclein (SNCA), parkin 2 (PARK2), leucine-rich repeat kinase 2 (LRRK2), PTEN-induced putative kinase 1 (PINK 1/PARK6), ATPase type 13A2 (ATP13A2), parkin RBR E3 ubiquitin-protein ligase (PRKN), and glucocerebrosidase genes (GBAs) [9,10].