Niemann-Pick disease is-

Niemann-Pick disease is a group of inherited, severe metabolic disorders in which sphingomyelin accumulates in lysosomes in cells. The lysosomes normally transpo material through and out of the cell. The prognosis is individual, but the severe form is fatal in toddlerhood and, in some cases, patients with the milder forms may have normal lifespans. This disease involves dysfunctional metabolism of sphingolipids, which are fats found in cell membranes, so it is a kind of sphingolipidosis. Sphingolipidoses, in turn, are included in the larger family of lysosomal storage diseases.