SNCA and Parkinson disease: The majority of PD cases are idiopathic, while 5–10% of PD cases are familial and linked to mutations in multiple genes, such as α-synuclein (SNCA), Parkin (PRKN), PTEN-induced putative kinase 1 (PINK1), DJ-1, VPS35, glucocerebrosidase (GBA), and leucine-rich repeat kinase 2 (LRRK2) [4].