LDLR and familial hypercholesterolemia: When fed a high‐fat Western diet, ldlr−/− mice develop atherosclerosis mimicking that in human familial hypercholesterolemia, in which genetic defects in LDL receptor function increase the risk of early heart attack >10‐fold.14,36 Atherosclerotic lesions are formed by the accumulation of cholesterol‐laden macrophages in the aortic wall.