In contrast, 5–10% of PD cases are familial and associated with mutations in multiple genes, including α-synuclein (SNCA), Parkin (PRKN), PTEN-induced putative kinase 1 (PINK1), DJ-1, VPS35, glucocerebrosidase (GBA), and leucine-rich repeat kinase 2 (LRRK2) [6]. Here, LRRK2 is linked to Parkinson disease.