After disease-causing genes were identified using linkage analysis and association analysis with familial and sporadic cases of PD, SNCA (α-Synuclein) [26,27] and several other familial PD-linked genes were described, such as parkin, DJ-1, PINK1, and LRRK2 [28,29,30]. The gene discussed is PRKN; the disease is Parkinson disease.