APOE and early-onset autosomal dominant Alzheimer disease: Pertaining to its role in lipid metabolism and cholesterol homeostasis (2), APOE is the strongest genetic risk factor for Alzheimer’s disease (AD) (3) and has been implicated in several metabolic (4, 5, 6), cardiovascular (7) and other neurodegenerative diseases (8, 9, 10, 11).