Test Id : AGAW
Alpha-Galactosidase, Leukocytes
Useful For
Suggests clinical disorders or settings where the test may be helpful
Diagnosis of Fabry disease in male patients
Verifying abnormal serum alpha-galactosidase results in male patients with a clinical presentation suggestive of Fabry disease
This test is not useful for patients undergoing a work-up for a meat or meat-derived product allergy.
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Fabry disease is caused by deficient activity of the enzyme alpha-galactosidase A and results in damage to multiple organs including the kidney, heart, and brain.
Treatment with enzyme replacement therapy is available for individuals with Fabry disease.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
Additional information is available:
-Fabry Disease: Newborn Screen-Positive Follow-up
-Fabry Disease Diagnostic Testing Algorithm
If the patient has abnormal newborn screening results for Fabry disease. Refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)
Method Name
A short description of the method used to perform the test
Flow Injection Analysis-Tandem Mass Spectrometry
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
Alpha-Galactosidase A
Anderson Fabry Disease
Anderson-Fabry Disease
Ceramide Trihexosidase
Fabry Disease
Fabry's Disease
Galactosidase, Alpha
GLA Deficiency
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
Additional information is available:
-Fabry Disease: Newborn Screen-Positive Follow-up
-Fabry Disease Diagnostic Testing Algorithm
If the patient has abnormal newborn screening results for Fabry disease. Refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)
Specimen Type
Describes the specimen type validated for testing
Whole Blood ACD
Ordering Guidance
If testing is needed for assessment of meat or meat-derived product allergy, order either ALGAL / Galactose-Alpha-1,3-Galactose (Alpha-Gal), IgE, Serum or APGAL / Galactose-Alpha-1,3-Galactose (Alpha-Gal) Mammalian Meat Allergy Profile, Serum.
Carrier detection using enzyme levels is unreliable for female patients as results may be within the normal values. Order FABRZ / Fabry Disease, Full Gene Analysis, Varies for testing carrier status.
Shipping Instructions
For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 days of collection to be stabilized. Collect specimen Monday through Thursday only and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
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.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
Forms
1. New York Clients-Informed consent is required. Document on the request form or electronic order that a copy is on file. The following documents are available:
-Informed Consent for Genetic Testing (T576)
-Informed Consent for Genetic Testing-Spanish (T826)
2. Biochemical Genetics Patient Information (T602)
3. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.
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.
2 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 Fabry disease in male patients
Verifying abnormal serum alpha-galactosidase results in male patients with a clinical presentation suggestive of Fabry disease
This test is not useful for patients undergoing a work-up for a meat or meat-derived product allergy.
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Fabry disease is caused by deficient activity of the enzyme alpha-galactosidase A and results in damage to multiple organs including the kidney, heart, and brain.
Treatment with enzyme replacement therapy is available for individuals with Fabry disease.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
Additional information is available:
-Fabry Disease: Newborn Screen-Positive Follow-up
-Fabry Disease Diagnostic Testing Algorithm
If the patient has abnormal newborn screening results for Fabry disease. Refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Fabry disease is an X-linked lysosomal storage disorder resulting from deficient activity of the enzyme alpha-galactosidase A (alpha-Gal A) and the subsequent deposition of glycosylsphingolipids in tissues throughout the body, in particular in the kidney, heart, and brain. Variants within the GLA gene cause Fabry disease and more than 630 genetic alterations have been identified. Severity and onset of symptoms are dependent on the amount of residual enzyme activity. The classic form of Fabry disease occurs in male patients who have less than 1% alpha-Gal A activity. Symptoms usually appear in childhood or adolescence and can include acroparesthesias (burning pain in the extremities), gastrointestinal issues, multiple angiokeratomas, reduced or absent sweating, corneal opacity, and proteinuria. In addition, progressive kidney involvement leading to end-stage kidney disease (ESRD) typically occurs in adulthood, followed by cardiovascular and cerebrovascular disease. The estimated incidence varies from 1 in 3000 infants detected via newborn screening to 1 in 10,000 male patients diagnosed after onset of symptoms.
Male patients with residual alpha-Gal A activity greater than 1% may present with 1 of 3 variant forms of Fabry disease with onset of symptoms later in life: a kidney variant associated with ESRD but without the pain or skin lesions; a cardiac variant typically presenting in the 6th to 8th decade with left ventricular hypertrophy, cardiomyopathy and arrhythmia, and proteinuria, but without ESRD; and a cerebrovascular variant presenting as stroke or transient ischemic attack. The variant forms of Fabry disease may be underdiagnosed.
Female patients who are carriers of Fabry disease can have clinical presentations ranging from asymptomatic to severely affected. Measurement of alpha-Gal A activity is not generally useful for identifying carriers of Fabry disease, as many of these individuals will have normal levels. Therefore, molecular genetic analysis of the GLA gene (FABRZ / Fabry Disease, Full Gene Analysis, Varies) is recommended to detect carriers.
Unless irreversible damage has already occurred, treatment with enzyme replacement therapy has led to significant clinical improvement in affected individuals. In addition, some adult patients may be candidates for an oral chaperone therapy. For this reason, early diagnosis and treatment are desirable and, in a few US states, early detection of Fabry disease through newborn screening has been implemented.
Absent or reduced alpha-Gal A in blood spots (AGABS / Alpha-Galactosidase, Blood Spot), leukocytes (this test), or serum (AGAS / Alpha-Galactosidase, Serum) can indicate a diagnosis of classic or variant Fabry disease. The biomarkers globotriaosylsphingosine (LGBWB / Globotriaosylsphingosine, Blood) and ceramide trihexosides (CTSU / Ceramide Trihexosides and Sulfatides, Random, Urine) may be elevated in patients with Fabry disease and may aid in the diagnostic evaluation of female patients. Molecular sequence analysis of the GLA gene (FABRZ / Fabry Disease, Full Gene Analysis, Varies) allows for detection of the disease-causing variant in both male and female patients.
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 =10.32 nmol/hour/mg protein
An interpretative report will be provided.
Note: Results from this assay do not reflect carrier status because of individual variation of alpha-galactosidase enzyme levels.
Interpretation
Provides information to assist in interpretation of the test results
Values below the reference range are consistent with a diagnosis Fabry Disease.
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
Individuals with pseudodeficiency allelic variants can show reduced alpha-galactosidase A enzyme activity with this assay.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. ACMG Newborn Screening ACT Sheets. Accessed October 30, 2023. Available at www.acmg.net/ACMG/Medical-Genetics-Practice-Resources/ACT_Sheets_and_Algorithms/ACMG/Medical-Genetics-Practice-Resources/ACT_Sheets_and_Algorithms.aspx?hkey=9d6bce5a-182e-42a6-84a5-b2d88240c508
2. Desnick RJ, Ioannou YA, Eng CM: Alpha-galactosidase A deficiency: Fabry disease. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed March 3, 2022. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225546984
3. De Schoenmakere G, Poppe B, Wuyts B, et al: Two-tier approach for the detection of alpha-galactosidase A deficiency in kidney transplant recipients. Nephrol Dial Transplant. 2008 Dec;23(12):4044-4048. doi: 10.1093/ndt/gfn370
4. Mehta A, Hughes DA: Fabry disease. In: Adam MP, Ardinger HH, Pagon RA, et al: eds. GeneReviews [Internet]. University of Washington, Seattle; 2002. Updated January 27, 2022. Accessed March 3, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1292/
5. Laney DA, Bennett RL, Clarke V, et al: Fabry disease practice guidelines: recommendations of the National Society of Genetic Counselors. J Genet Couns. 2013 Oct;22(5):555-564. doi: 10.1007/s10897-013-9613-3
6. Laney DA, Peck DS, Atherton AM, et al: Fabry disease in infancy and early childhood: a systematic literature review. Genet Med. 2015 May;17(5):323-330. doi: 10.1038/gim.2014.120
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 acid sphingomyelinase, beta-glucocerebrosidase, acid alpha-glucosidase, alpha-galactosidase, galactocerebrosidase and alpha-L-iduronidase. The sample is then purified by liquid-liquid extraction. The extract is evaporated and reconstituted before analysis by tandem mass spectrometry.(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
Assay 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 :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
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.
82657
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| AGAW | Alpha-Galactosidase, Leukocytes | 24049-9 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 606261 | Alpha-Galactosidase, Leukocytes | 24049-9 |
| 606262 | Interpretation | 59462-2 |
| 606263 | Reviewed By | 18771-6 |