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.
Some forms of the disease can be diagnosed during ante natal screening. After birth, the diagnosis is made by a liver biopsy where liver tissue specimens are obtained and studied under a microscope. Niemann-Pick disease does not have a complete cure, though treatments that halt the disease progression are being studied. Affected children tend to die of infection or progressive dysfunction of the central nervous system.Results of a survey shows the extrapolation of Prevalence Rate of Niemann-Pick disease type C2 in Russia is 959.There is current research aiming to develop recombinant human acid sphingomyelinase for the potential treatment of NP disease types A and B. A phase 1 clinical trial was completed in 2009. A phase 2 trial is planned.