LRRK2 and Parkinson disease: Mutations of seven genes have been definitely linked to PD, and these are PARK1/4 (SNCA, encoding α-synuclein), PARK2 (PRKN, encoding parkin), PARK7 (encoding parkinsonism associated deglycase, best known as DJ-1), PINK1 (encoding phosphatase and tensin homolog (PTEN)-induced kinase 1), LRRK2 (encoding leucine-rich repeat kinase 2), VPS35 (encoding vacuolar protein sorting ortholog 35, involved in autophagy), and GBA1 (GTP-binding protein type A1, encoding lysosomal β-glucocerebrosidase 1) [20,21,22,23,24,25,26].