HTRA2 and Parkinson disease: To date, numerous genes have been reported to be implicated in the PD evolution, encompassing α-synuclein (SNCA) [46,47,48] Parkin RBR E3 ubiquitin–protein ligase (Parkin) [49], ubiquitin carboxy (C)-terminal hydrolase L1 (UCHL1) [50], PTEN-induced kinase 1 (PINK1) [51], protein deglycase (DJ-1) [52], leucine-rich repeat kinase 2 (LRRK2) [53], glucocerebrosidase (GBA) [54], vacuolar protein sorting 35 (VPS35) [55], neuronal P-type adenosine triphosphate (ATP)ase gene (ATP13A2) [56], high temperature requirement A2 (HTRA2) [57], and synaptojanin 1 (SYNJ1) [58].