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Lysosomal enzymes (acid hydrolases) are responsible for
breaking down complex chemicals within a cell. The breakdown products are then
eliminated from the cell or reused. A deficiency of any one of these enzymes
will lead to a "storage disease" which is usually associated with developmental
regression.
A lysosomal storage disease should be suspected in infants or
children with growth failure, developmental regression, corneal or lens
clouding, hepato- and/or splenomegaly, coarsening facial features and skeletal
abnormalities.
Different storage diseases may have similar clinical features,
thus it may be necessary to measure a number of different enzyme activities
prior to finding the one deficient in a particular patient. The Metabolic
Laboratory of the Greenwood Genetic Center offers a lysosomal enzyme panel that
includes the enzymes listed below. These tests can also be ordered on an
individual basis, if desired.
- α-fucosidase (Fucosidosis)
- α-galactosidase (Fabry disease)
- α-iduronidase (Hurler syndrome; MPS I)
- α-mannosidase (α-mannosidosis)
- α-neuraminidase (sialidosis) *available on fibroblasts
only
- β-galactosidase (GM1 gangliosidosis)
- β-glucosidase (Gaucher disease)
- β-glucuronidase (Sly syndrome; MPS VII)
- β-mannosidase (β-mannosidosis)
Specimen requirements: Lysosomal enzymes may be
measured in cultured skin fibroblasts or leukocytes.
Transport: Please contact the laboratory before
transporting tissue for enzyme assay. The laboratory will separate leukocytes
for assay if a blood sample is sent. Send a green top tube (7-10 ml) by courier
or 24 hour delivery - not frozen. Insure that the specimen will not freeze or
get above room temperature during shipment. Fresh tissue for culture (skin
biopsy, etc.) should be sent by courier or 24-hour delivery.
Standard of analysis: Assays for lysosomal enzymes will
employ 4-methylumbelliferyl substrate and will be quantitated per mg protein
(tissue) or per ml (serum, plasma).
Time required: Most assays will be complete in one
week; assays of cultured cells may take 3-4 weeks.
Special requests: Any type of special request must be
made directly with the laboratory.
Report: Written reports with interpretation are mailed
to the referring physician. Abnormal results will also be telephoned to the
referring physician.
CPT Code: 82657 for single enzyme; 82657(x8) for panel
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