Test Id : GALCR
Galactocerebrosidase Reflex, Leukocytes
Useful For
Suggests clinical disorders or settings where the test may be helpful
Diagnosis of Krabbe disease as a confirmatory reflex of the six-enzyme panel
Follow-up testing for evaluation of an abnormal newborn screening result for Krabbe disease
This test is not recommended for carrier detection because of the wide range of enzymatic activities observed in carriers and noncarriers.
Method Name
A short description of the method used to perform the test
Only orderable as a reflex. For more information see LSD6W / Lysosomal Disorders, Six-Enzyme Panel, Leukocytes.
Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
Aliases
Lists additional common names for a test, as an aid in searching
B-Galactosidase Galactosylceramide, Leukocytes
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 validated for testing
Whole Blood ACD
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Only orderable as a reflex. For more information see LSD6W / Lysosomal Disorders, Six-Enzyme Panel, Leukocytes.
Container/Tube:
Preferred: Yellow top (ACD solution B)
Acceptable: Yellow top (ACD solution A) or lavender top (EDTA)
Specimen Volume: 6 mL
Collection Instructions: Send whole blood specimen in original tube. Do not aliquot.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
4 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood ACD | Refrigerated (preferred) | 6 days | |
| Ambient | 6 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Diagnosis of Krabbe disease as a confirmatory reflex of the six-enzyme panel
Follow-up testing for evaluation of an abnormal newborn screening result for Krabbe disease
This test is not recommended for carrier detection because of the wide range of enzymatic activities observed in carriers and noncarriers.
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 the enzyme, galactocerebrosidase (GALC). GALC facilitates the lysosomal degradation of psychosine (galactosylsphingosine) and 3 other substrates (galactosylceramide, lactosylceramide, and lactosylsphingosine) causing severe demyelination throughout the brain. Krabbe disease is caused by variants in the GALC gene, and it has an estimated frequency of 1 in 100,000 births. Although rare, a few infants with an infantile Krabbe disease-like phenotype due to deficiency of saposin A have been found. Saposin-A is a sphingolipid activator protein that assists galactocerebrosidase in its action on galactosylceramide.
Severely affected infants typically present between ages 3 to 6 months with increasing irritability and sensitivity to stimuli. Rapid neurodegeneration including white matter disease follows, with death usually occurring by age 2. Some individuals have later 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.
Newborn screening for Krabbe disease has been implemented in some states. The early (presymptomatic) identification and subsequent testing of infants at risk for Krabbe disease may be helpful in reducing the morbidity and mortality associated with this disease. While treatment is mostly supportive, hematopoietic stem cell transplantation has shown some success if performed early, prior to onset of neurologic damage.
Reduced or absent galactocerebrosidase in leukocytes can indicate a diagnosis of Krabbe disease; however, a number of alterations in the GALC gene have been identified that result in reduced galactocerebrosidase activity in vitro but do not cause disease. The biomarker, psychosine (PSY / Psychosine, Blood Spot, PSYR / Psychosine, Whole Blood, or PSYCF / Psychosine, Spinal Fluid), has been shown to be elevated in patients with active Krabbe disease. Molecular sequencing of the GALC gene (GALC / Krabbe Disease, GALC Gene Sequencing with Deletion/Duplication, Varies) is necessary for differentiating alternations from disease-causing variants in affected patients and for 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.
Only orderable as a reflex. For more information see LSD6W / Lysosomal Disorders, Six-Enzyme Panel, Leukocytes.
> or =0.300 nmol/hr/mg protein
Interpretation
Provides information to assist in interpretation of the test results
When abnormal results are detected, a detailed interpretation is given, including an overview of the results and of their significance, a correlation to available clinical information, elements of differential diagnosis, recommendations for additional biochemical testing, and in vitro, confirmatory studies (enzyme assay, molecular analysis), name and phone number of key contacts who may provide these studies, and a phone number to reach one of the laboratory directors in case the referring physician has additional questions.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Pseudodeficiency of galactocerebrosidase causes reduced enzymatic activity but does not cause disease.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Elliott S, Buroker N, Cournoyer JJ, et al. Pilot study of newborn screening for six lysosomal storage diseases using Tandem Mass Spectrometry. Mol Genet Metab. 2016;118(4):304-309
2. Matern D, Gavrilov D, Oglesbee D, Raymond K, Rinaldo P, Tortorelli S. Newborn screening for lysosomal storage disorders. Semin Perinatol. 2015;39(3):206-216
3. Orsini JJ, Escolar ML, Wasserstein MP, et al. Krabbe disease. In: Adam MP, Feldman J, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 1993-2025. Updated October 11, 2018. Accessed July 22, 2025. Available at www.ncbi.nlm.nih.gov/books/NBK1238/
4. Liao HC, Spacil Z, Ghomashchi F, et al. Lymphocyte galactocerebrosidase activity by LC-MS/MS for post-newborn screening evaluation of Krabbe disease. Clin Chem. 2017;63(8):1363-1369
5. Lin N, Huang J, Violante S, et al. Liquid chromatography-tandem mass spectrometry assay of leukocyte acid alpha-glucosidase for post-newborn screening evaluation of Pompe disease. Clin Chem. 2017;63(4):842-851
Method Description
Describes how the test is performed and provides a method-specific reference
The specimens are incubated with a mix of substrate and internal standard for galactocerebrosidase and alpha galactosidase (GLA). The reaction is then stopped using acetonitrile, centrifuged, and a portion of the supernatant is prepared for analysis by liquid chromatography-tandem mass spectrometry. GLA is included to verify sample integrity.(Unpublished Mayo method)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Preanalytical processing: Monday through Saturday
Testing performed: Monday, Wednesday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
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
Indicates the location of the laboratory that performs the test
Fees :
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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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
82542