Type A and B Niemann-Pick are diagnosed by measuring the ASM (acid sphingomylinase) 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.
Additional
tests might include:
·
Slit-lamp
eye exam
·
Bone
marrow aspiration
looking for foamy histiocytes that
have a mulberry appearance
·
Liver
biopsy
(usually not necessary)
·
Sphingomyelinase
assays
There is no available treatment for
Niemann-Pick disease. Present
attention is to genetic counseling and
prenatal diagnosis to determine that
the fetus
is normal. New advances in recombinant
DNA technology has
made it possible to clone
the gene
responsible for the production of
sphingomyelinase, which is the
beginning to better understanding of
the disease and possible future
therapy.
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