NPC1 and cholestasis: The importance of NPC1 and NPC2 in cholesterol transport is illustrated in patients with NPC disease, a severe neurodegenerative disorder caused by loss-of-function mutations in NPC1 or NPC2. Dysfunction of these proteins results in accumulation of cholesterol in LE/LY compartments, leading mainly to neurological symptoms, but also to progressive liver disease characterized by cholestasis, hepatomegaly, and fibrosis or cirrhosis [[21], [22], [23]].