Early onset familial PD arises from mutations in the autosomal recessive genes PARKIN, PTEN-induced kinase-1 (PINK1), and DJ-1 [94] while late onset PD is associated with dominantly-inherited mutations in leucine-rich repeat kinase 2 (LRRK2) and α-synuclein. Here, LRRK2 is linked to Parkinson disease.