Apolipoprotein‐E knockout (ApoE−/−) mice, a widely used model of atherosclerosis, spontaneously develop hypercholesterolemia and atherosclerotic plaques when fed a normal diet (Plump et al. 1992; Zhang et al. 1992; Nakashima et al. 1994). The gene discussed is APOE; the disease is Hypercholesterolemia.