Familial forms of PD involve α-synuclein gene mutations (SNCA), ubiquitin C-terminal hydrolase L1 (UCHL-1), phosphatase and tensin homolog-induced putative kinase 1 (PINK1), Parkin (PRKN), protein deglycase (DJ-1), and leucine-rich repeat kinase 2 (LRRK2) [71]. Here, SNCA is linked to Parkinson disease.