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Niemann-Pick Disease |
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Niemann-Pick DiseaseWhat is Niemann-Pick Disease?Niemann-Pick disease (NP) is an inherited metabolic disorder in which harmful quantities of a fatty substance accumulate in the spleen, liver, lungs, bone marrow, and, in some people, the brain. The disease is subdivided into 4 related types. In types A and B, insufficient activity of an enzyme called sphingomyelinase causes the build up of toxic amounts of sphingomyelin, a fatty substance present in every cell of the body. Types C and D are characterized by a defect that disrupts the transport of cholesterol between brain cells. Type A, Infantile NP is the most common type, and occurs in infants. It is characterized by jaundice, enlargement of the liver, and profound brain damage. Children with this type rarely live beyond 18 months. Type B, Juvenile Nonneuronopathic NP, involves enlargement of the liver and spleen, which characteristically occurs in the pre-teen years. The brain is not affected. Types C and D may appear early in life or be delayed into the teen years. Children with these types have only moderate enlargement of the spleen and liver, but brain damage may be extensive and cause an inability to look up and down, difficulty in walking and swallowing, and progressive loss of vision and hearing. Type D only occurs in people with an ancestral background in Nova Scotia. Treatment of Niemann-Pick DiseaseThere is currently no effective treatment for patients with type A. Bone marrow transplantation has been attempted in a few patients with type B, and encouraging results have been reported. The development of enzyme replacement and gene therapies might also be helpful for those with type B. Children and young teens with types C and D are frequently placed on a low-cholesterol diet, but its clinical benefit is not convincing. What is the prognosis of Neimann-Pick Disease?Patients with type A die in infancy. Type B patients may live a comparatively long time, but many require supplemental oxygen because of lung impairment. The life expectancies of patients with types C and D are variable. Some patients die in childhood while others, who appear to be less drastically affected, live into adulthood. What research is being done on Nieman-Pick Disease?Investigators at NINDS have identified two different genes that, when defective, contribute to Niemann-Pick disease, types C and D. Research supported by the NINDS also includes studies to understand how genetic defects can cause neurological disorders. These studies open promising new avenues for the development of successful treatments. Dementia Overview
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