Niemann-Pick disease is a condition that affects many body systems. It has a wide range of symptoms that vary in severity. Niemann-Pick disease is divided into four main types: type A, type B, type C1, and type C2. These types are classified on the basis of genetic cause and the signs and symptoms of the condition.Niemann–Pick diseases are a subgroup of lipid storage disorders called sphingolipidoses in which harmful quantities of fatty substances, or lipids, accumulate in the spleen, liver, lungs, bone marrow, and brain. In the classic infantile type-A variant, a missense mutation causes complete deficiency of sphingomyelinase. Sphingomyelin is a component of cell membrane including the organellar membrane, so the enzyme deficiency blocks degradation of lipid, resulting in the accumulation of sphingomyelin within lysosomes in the macrophage-monocyte phagocyte lineage. Affected cells become enlarged, sometimes up to 90 μm in diameter, secondary to the distention of lysosomes with sphingomyelin and cholesterol. Histology shows lipid-laden macrophages in the marrow and "sea-blue histiocytes" on pathology. Numerous small vacuoles of relatively uniform size are created, giving the cytoplasm a foamy appearance.
Several treatment options, including bone marrow transplants, enzyme replacement therapy, and gene therapy have been used. Research is ongoing to determine the effectiveness of such treatments. A medication called miglustat is currently used to treat type C. Miglustat is classified as an enzyme inhibitor, and works by preventing the body from producing fatty substances (in the case of type C, cholesterol) so that less of it will build up in the body. And there is no treatment for type A and D.No specific treatment is known for type A, but symptoms are treated. In adult patients with type B, physicians try to keep cholesterol levels down to normal levels. Results of a survey shows the extrapolation of Prevalence Rate of Niemann-Pick disease type C2 in Ireland is 26 for the estimated total population of 3,96,95,582.Investigators at the NINDS have identified two different genes that, when defective, contribute to Niemann-Pick disease type C. NINDS scientists are studying the mechanisms by which lipids accumulating in these storage diseases causes harm to the body. Additional research studies hope to identify biomarkers (signs that may indicate risk of a disease and improve diagnosis) for the lipid storage disorders.