Monogenic PD with autosomal-dominant inheritance is caused by mutation in α-synuclein gene (SNCA) or leucine-rich repeat kinase 2 gene (LRRK2), whereas the form with autosomal recessive inheritance by mutations in the genes encoding Parkin 2 (PARK2), PTEN-induced putative kinase 1 (PINK1), protein deglycase DJ-1 (PARK7), and protein ATP13A2 (PARK9). Here, PINK1 is linked to Parkinson disease.