Decreased levels of PPP enzymes have been identified in PD patients along with mutations in genes encoding α-synuclein, Parkin, PTEN Induced Kinase 1 (PINK1), Leucine Rich Repeat Kinase 2 (LRRK2), and DJ-1 in familial forms of PD [110, 111]. Here, PRKN is linked to Parkinson disease.