NPC1 and Niemann-Pick disease, type C1: Niemann-Pick C1 (NPC1) disease is a recessive autosomal disease caused by mutations that decrease NPC1 protein activity and result in an accumulation of LDL cholesterol in lysosomes (Carstea et al., 1997; Lloyd-Evans et al., 2008) which affects roughly 1 in 92,104 (Wassit et al., 2016).