Test ID: CBGT
Galactocerebrosidase, Fibroblasts
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
Additional Tests Lists test(s) that are always performed, at an additional charge, with the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| CRYOB | Cryopreserve for Biochem Studies | No | Yes |
| FIBR | Fibroblast Culture | Yes | Yes |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
When this test is ordered, a fibroblast culture and cryopreservation for biochemical studies will always be performed at an additional charge. However, for multiple lysosomal enzyme assays on a patient utilizing fibroblast culture, only 1 culture is required regardless of the number of enzyme assays ordered. If viable cells are not obtained within 10 days, client will be notified.
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
CBGT/8297: Radioisotopic
FIBR/8482: Cultivated from Biopsy as Monolayer
CRYOB/88832: Fibroblast Subculture Followed by Cryopreservation and Storage
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, Fibroblasts
Cerebroside B-Galactosidase
Cerebroside Beta-Galactosidase
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.
This test is not recommended for prenatal testing.
Forms:
1. 1. 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.
2. 2. If not ordering electronically, submit a Biochemical Genetics Request Form (Supply T439) with the specimen.
Submit only 1 of the following specimens:
Specimen Type: Cultured fibroblasts
Container/Tube: T-75 or T-25 flask
Specimen Volume: 1 full T-75 flask or 2 full T-25 flasks
Specimen Stability Information: Ambient (preferred)/Refrigerated <24 hours
Specimen Type: Skin biopsy
Container/Tube: Sterile container with any standard cell culture media (eg, minimal essential media, RPMI 1640). The solution should be supplemented with 1% penicillin and streptomycin. Tubes can be supplied upon request (Eagle's minimum essential medium with 1% penicillin and streptomycin [Supply T115]).
Specimen Volume: 4-mm punch
Specimen Stability Information: Refrigerated (preferred)/Ambient
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 | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Specimen in formalin or fixative preservative |
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 |
|---|---|---|
| Tissue | Varies | |
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 galactocerebrosidase. A deficiency of this enzyme leads to an accumulation of galactocerebrosidase causing severe demyelination throughout the brain. Krabbe disease is caused by mutations in the GALC gene, and it has an estimated frequency of 1 in 100,000 births.
Severely affected individuals typically present between 3 to 6 months of age with increasing irritability and sensitivity to stimuli. Rapid neurodegeneration including white matter disease follows with death usually occurring by age 2. A small subset of individuals have late onset forms of the disease that are characterized by ataxia, vision loss, weakness, and psychomotor regression presenting anywhere from age 6 months to the seventh decade of life. 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 damage has occurred.
Reduced or absent galactocerebrosidase in fibroblasts or leukocytes (CBGC/8816 Galactocerebrosidase, Leukocytes) can indicate a diagnosis of Krabbe disease. Molecular sequencing of the GALC gene (GALCS/60696, Krabbe Disease, Full Gene Analysis and Large [30 kb] Deletion, PCR) allows for detection of the disease-causing mutations in affected patients and carrier detection in family members.
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.
> or =1.20 nmol/h/mg protein
Interpretation Provides information to assist in interpretation of the test results
Values below the reference range are consistent with a diagnosis of Krabbe disease.
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.
Interfering factors:
-Lack of viable cells or bacterial contamination
-Failure to transport tissue in an appropriate media
-Excessive transport time
-Exposure of the specimen to temperature extremes (freezing or temperatures >37 degrees C)
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 has been labeled with tritium. The liberated [3H] 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.
Varies
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-Galactocerebrosidase
88233-Fibroblast culture
88240-Cryopreservation for biochemical studies
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 |
|---|---|---|
| 35587 | Galactocerebrosidase, Fibro | In Process |
| 35588 | Interpretation (CBGT) | In Process |
| 35589 | Reviewed By | In Process |
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