Test ID: CBGC
Galactosylceramide Beta-Galactosidase, Leukocytes
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosis of Krabbe disease
Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request
Diagnostic testing for patients with clinical signs and symptoms suspicious for Krabbe disease.
This test is not intended for carrier detection.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Radioisotopic
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
Beta-Galactosidase Galactosylceramide, Leukocytes
Cerebroside B-Galactosidase, WBC
Cerebroside Beta-Galactosidase(WBC)
Galactocerebrosidase
Galactocerebrosidase Deficiency
Galactosylceramidase Deficiency
Galactosylceramide
GALC Deficiency
Globoid Cell Leukodystrophy
Krabbe Disease
Krabbe's Disease
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Specimen must arrive within 48 hours of draw to be stabilized. Draw specimen Monday through Thursday only and not the day before a holiday. Specimen should be drawn and packaged as close to shipping time as possible.
Container/Tube:
Preferred: Yellow top (ACD solution B)
Acceptable: Yellow top (ACD solution A)
Specimen Volume: 7 mL
Collection Instructions: Do not transfer blood to other containers.
Forms: New York Clients-Informed consent is required. Please document on the request form or electronic order that a copy is on file. An Informed Consent for Genetic Testing (Supply T576) is available in Special Instructions.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole Blood ACD | Refrigerated (preferred) | 48 hours |
| Ambient | 48 hours |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Krabbe disease (globoid cell leukodystrophy) is an autosomal recessive disorder caused by a deficiency of galactosylceramide beta-galactosidase (GBG). A deficiency of this enzyme leads to an accumulation of galactosylceramide in globoid cells (multinucleated macrophages) causing severe demyelination throughout the brain. The toxic metabolite galactosylsphingosine (psychosine), an apoptotic compound, accumulates in oligodendrocytes and Schwann cells and contributes to disease pathogenicity.
Severely affected individuals typically present between 3 to 6 months of age with increasing irritability and sensitivity to stimuli. Rapid neurodegeneration follows with death usually occurring by age 2. There are later onset forms of the disease that are characterized by ataxia, vision loss, weakness, and psychomotor regression. The clinical course of Krabbe disease can be variable even within the same family. Treatment is mostly supportive, although hematopoietic stem cell transplantation has shown some success if treatment begins before neurologic damaged has occurred.
Krabbe disease is caused by mutations in the GALC gene located on 14q31. Over 60 mutations have been described to date. Molecular genetic analysis, including deletion/duplication analysis, is commercially available in the United States. Contact Mayo Medical Laboratories for recommendations or contact information for laboratories that offer this testing.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
21.5-59.2 mU/g of protein
Note: The upper limit of normal may change with the specific activity of the substrate. This is of no consequence since Krabbe patients are below the lower limit.
Interpretation Provides information to assist in interpretation of the test results
Values below the reference range are consistent with a diagnosis of Krabbe disease.
The upper limit of normal may change with the specific activity of the substrate. Elevated values have no known clinical significance.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Because of the wide range of enzymatic activities observed in carriers and noncarriers, this test is not recommended for carrier detection.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Wenger DA: Krabbe Disease. Available from http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=gene&part=krabbe Reviewed March 29, 2011
2. Enns GM, Steiner RD, Cowan TM: Lysosomal Disorders. In Pediatric Endocrinology and Inborn Errors of Metabolism. Edited by Sarafoglou K, Hoffman G, Roth KS, New York, McGraw- Hill Medical, 2009, p 744
Method Description Describes how the test is performed and provides a method-specific reference
The natural substrate, galactosylceramide (galactocerebroside), is used in this assay. The galactose moiety of the substrate is labeled with tritium. The liberated (3)H galactose is determined after it is separated from the unreacted galactosylceramide by solvent partitioning. (Suzuki K: Enzymic diagnosis of sphingolipidoses: globoid cell leukodystrophy [Krabbe's disease]. Methods Enzymol 1979;50:456-488; Radin NS: Labeled galactosyl ceramide and lactosyl ceramide. Methods Enzymol 1972;28:300-306)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Specimen are processed Monday through Sunday. Assay is performed on Wednesday; 8 a.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82658
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 8816 | Galactosylcer B-Galactosid, WBC | In Process |
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