NPC1L1 knockout mice are resistant to diet-induced hypercholesterolemia [5], and their cholesterol absorption rate decreases by about 70%, while the absorption of other lipids (such as triglycerides and phospholipids) is not affected, providing the compelling evidence that NPC1L1 specifically mediates the absorption of cholesterol [5, 6]. The gene discussed is NPC1L1; the disease is familial hypercholesterolemia.