Niemann-Pick disease overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief:
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Overview
Niemann-Pick disease (NPD) is a group of autosomal recessive disorders that are classified into two broad types. Types A and B NPD are lysosomal storage diseases due to sphingomyelinase deficiency. Type C NPD results from defective intracellular trafficking of cholesterol. Both types are featured by deposition of lipids such as cholesterol, sphingomyelin, and bisphosphonate in various organs. Types A and B are charachterized by an early age of onset and progressive CNS disease in type A. Type A typically has onset in the first 6 months, with rapidly progressive CNS deterioration, spasticity, failure to thrive, and massive hepatosplenomegaly. In contrast, type B has a later, more variable onset and progression of hepatosplenomegaly, with eventual development of cirrhosis and hepatic replacement by foam cells. Affected patients develop progressive pulmonary disease with dyspnea, hypoxemia, and a reticular infiltrative pattern on chest x-ray.
The diagnosis is established by markedly decreased (1–10% of normal) sphingomyelinase activity in nucleated cells. There is no specific treatment for Niemann-Pick disease. The efficacy of hepatic or bone marrow transplantation has not been proven yet. Clinical trials using enzyme therapy are expected in the near future.