Niemann-Pick Disease

Niemann-Pick disease (NP), also known as acid sphingomyelinase deficiency, is a group of rare genetic diseases of varying severity. These are inherited metabolic disorders in which sphingomyelin accumulates in lysosomes in cells of many organs. NP types A, A/B, and B are caused by mutations in the SMPD1 gene, which causes a deficiency of an acid sphingomyelinase (ASM). NP type C is now considered a separate disease, as SMPD1 is not involved, and there is no deficiency in ASM. These disorders involve the dysfunctional metabolism of sphingolipids, which are fats found in cell membranes. They can be considered as a kind of sphingolipidosis, which is included in the larger family of lysosomal storage diseases.