To investigate the precise effects of depleting ApoC3 on refractory hypercholesterolemia and atherosclerosis, we crossed ApoC3-deficient hamsters with a background of LDLR deficiency to generate a double knockout (DKO) hamster model (LDLR−/−, XApoC3−/−, DKO). This evidence concerns the gene APOC3 and familial hypercholesterolemia.