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Krabbe disease is caused by
the deficiency of galactosylceramide β-galactosidase, which results in the
accumulation of galactosylceramide specifically in brain white matter, causing a
neurological phenotype. The Greenwood Genetic Center is now offering clinical
enzyme analysis for galactosylceramide β-galactosidase.
Patients with the severe,
infantile form of Krabbe disease will typically present by 3-6 months of age
with rapidly progressive neurodegeneration, muscle rigidity, seizures,
irritability, vomiting, and blindness and/or deafness.
Approximately 10-15% of
cases exhibit a milder, late onset clinical phenotype, with patients presenting
with general weakness or stiffness, ataxia, vision loss, and some intellectual
regression.
Specimen required:
Galactosylceramide β-galactosidase enzyme analysis can be performed on either
leukocytes or cultured skin fibroblasts.
Transport:
The laboratory will isolate leukocytes for use in the enzyme assay if a whole
blood sample is sent. Collect blood in a sodium heparin green top tube (7-10
ml) and send via courier or 24-hour delivery at room temperature (not frozen).
Leukocytes must be isolated within 24 hours of sample collection. If sending
cultured fibroblasts, send two T-25 flasks for each patient, along with one
flask containing cultured fibroblasts from a normal control to validate sample
integrity during delivery. Fibroblasts should be sent by courier or 24-hour
delivery. Please contact the laboratory before transporting tissue for any
enzyme assay. 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: Enzyme
analysis is performed using a 4-methylumbelliferyl substrate as described in the
protocol developed by O.P. van Diggelen (2005) and will be quantitated per mg
protein.
Time required:
If cell culture is required, analysis should be completed in 3-4 weeks. If cell
culture is not required, analysis should be available within 2 weeks of sample
receipt.
Reports:
Written reports with interpretation are mailed to the referring physician. When
an abnormality is detected the report will also be telephoned to the referring
physician.
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