PRKN and Parkinson disease: In recent years, mutations in six genes have been identified as causes of PD: SNCA (which encodes α-synuclein), PARK2 (parkin), PINK1 (PTEN-induced kinase protein 1), UCHL1 (ubiquitin carboxyl-terminal hydrolase isozyme L1), DJ1 (protein DJ-1), and LRRK2 (leucine-rich repeat serine/threonine-protein kinase 2).