NPC1 and Niemann-Pick disease, type C1: Niemann-Pick disease, type C1 (NPC1) is a rare, autosomal recessive, lipid storage disorder caused by mutations in NPC1, thereby resulting in intracellular lipid trafficking defects leading to the accumulation of unesterified cholesterol and sphingolipids in the late endosomal/lysosomal system [1].