Several studies have been conducted in APOE mice on the effects of HFDs, because clinical studies showed APOE4-positive individuals have increased risk of metabolic syndrome (Arbones-Mainar et al., 2008; Torres-Perez et al., 2016) and obese APOE4 carriers have increased metabolic disturbances when compared to APOE3 carriers (Elosua et al., 2003). The gene discussed is APOE; the disease is metabolic syndrome.