SNCA and Parkinson disease: PD, marked by dopaminergic neuron degeneration and Lewy body formation, is associated with mutations in the SNCA gene encoding alpha-synuclein (α-Syn), as well as other genes such as leucine-rich repeat kinase 2 (LRRK2), Parkin RBR E3 ubiquitin-protein ligase (PARK2), PTEN-induced kinase 1 (PINK1), and protein deglycase (DJ-1).