In a longitudinal natural history study, nearly 20% of the patients died. For those classified into type C, they may have mild hepatosplenomegaly, but their central nervous system is profoundly affected. Niemann–Pick disease, SMPD1-associated, which includes types A and BNiemann–Pick disease type A: classic infantile
Niemann–Pick disease type B: visceralNiemann–Pick disease, type C: subacute/juvenile, includes types C1 (95% of type C) and C2. Type C is the most common form of the disease Type C2 is a rare form of the disease.Niemann–Pick disease type D (or Nova Scotia form) is now believed to be the same condition as Niemann–Pick disease type C. Two poorly characterized forms of Niemann–Pick disease have also been described as types E and F.

Treatment
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. If statins are used, they monitor liver function. If the spleen is enlarged and platelet levels low, acute episodes of bleeding may require transfusions of blood products. If they have symptoms of interstitial lung disease, they may need oxygen.Anecdotally, organ transplant has been attempted with limited success. Future prospects include enzyme replacement and gene therapy. Bone marrow transplant has been tried for type B.In January 2009, Actelion announced the drug miglustat (Zavesca) had been approved in the European Union for the treatment of progressive neurological manifestations in adult patients and pediatric patients with NPC. The drug is available to patients in the United States on an experimental basis.
In March 2010, the FDA requested additional preclinical and clinical information regarding Zavesca from Actelion before making a final decision on approving the drug in the United States for NPC.Olipudase alfa (Xenpozyme) was approved for medical use in Japan in March 2022. Prognosis
Highly variable, infantile neurovisceral Niemann Pick disease (Type A ASMD) is usually fatal before 3 years of age. In Type B ASMD  mortality before adulthood is common. But many patients live well into adulthood and may reach a normal lifespan. Diagnoses have been made in the 7th decade of life. Type C is an entirely different disorder, which also has a highly variable prognosis. Incidence
The incidence among Ashkenazi Jews is estimated to be about one in 40,000 for type A of Niemann–Pick disease. The incidence of both Niemann–Pick disease types A and B in all other populations is estimated to be one in 250,000. The incidence of Niemann–Pick disease type C is estimated to be one in 150,000. History
Albert Niemann published the first description of what now is known as Niemann–Pick disease, type A, in 1914. Ludwig Pick described the pathology of the disease in a series of papers in the 1930s.In 1961, the classification of Niemann–Pick disease into types A, B, and C was introduced, and also contained a type D, called the "Nova Scotian type". Genetic studies showed that type D is caused by the same gene as type C1, and the type D designation is no longer used.