APOE and Parkinson disease: Comprehensive analyses of patients with mutations in PINK1, DJ1, LRRK2, UCHL1, MAPT, GBA, NAT2, INOS2A, GAK, HLA-DRA, APOE, and SNCA have significantly increased our understanding regarding the morphological, and pathological aspects seen in clinical and preclinical stages of PD [6, 7].