Several monogenic forms of PD have been linked to genes including α-synuclein (α-syn), Leucine-rich repeat kinase 2 (LRRK2), PTEN-induced kinase 1 (PINK1), Parkin, DJ-1, Glucosylceramidase beta, and Coiled-coil-helix-coiled-coil-helix domain containing 2 [13]. Here, LRRK2 is linked to Parkinson disease.