A primary role of mitochondrial dysfunction in this process was boosted by the identification of genes related to familial forms of PD: α-synuclein (SNCA), leucine-rich repeat kinase 2 (LRRK2), PTEN-induced putative kinase 1 (PINK1), parkin RBR E3 ubiquitin protein ligase, also known as Parkin, (PRKN), DJ-1 (PARK7), and vacuolar sorting protein 35 (VPS35; Figure 1). Here, PINK1 is linked to Parkinson disease.