Niemann-Pick disease type C (NPC) is an autosomal recessive lysosomal lipid storage disorder with progressive neurodegeneration.79 NPC is classified as type C1 (NPC1) or type C2 (NPC2), which are caused by mutations in the NPC1 or NPC2 genes, respectively. The gene discussed is NPC1; the disease is Niemann-Pick disease type C.