APOE and Alzheimer disease: The role of apoE4 in cognitive performance and AD has been assessed in mouse models [23], including models expressing APOE ε4 in brain on a murine Apoe deficient background, models expressing APOE ε4 by targeted Apoe replacement [24] and more recently also in models where specifically the rodent hepatic Apoe was replaced by human ε4 [25, 26].