Niemann-Pick
Alternate Names : Sphingomyelinase Deficiency (Type A Niemann-Pick Disease)
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Niemann-Pick Diagnosis & Tests
Type A and B Niemann-Pick are diagnosed by measuring the ASM (acid sphingomyelinase) activity in white blood cells. The test can be performed after taking a small blood sample from suspected individuals. This test will be able to identify persons with the disease, but is unreliable in detecting persons who may be carriers.
However, it is possible to diagnose Types A and B carriers by DNA testing because the gene containing the blueprint for ASM has been cloned and many of its mutations identified.
Type C Niemann-Pick is initially diagnosed by taking skin biopsy, growing the cells in the laboratory, and then studying their ability to transport and store cholesterol. It is important that tests for both transport and storage be performed. Genetic testing is feasible following the discovery of 2 genes that cause Niemann-Pick type C disease.
Additional tests might include:
- Slit-lamp eye exam
- Liver biopsy or bone marrow aspiration looking for foamy histiocytes that have a mulberry appearance
- Liver biopsy (usually not necessary)
- Sphingomyelinase assays
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