Test Catalog

Test Id : AGABS

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Alpha-Galactosidase, Blood Spot

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

Diagnosis of Fabry disease in male patients using blood spot specimens

 

Verifying abnormal serum alpha-galactosidase results in male patients with a clinical presentation suggestive of Fabry disease

 

Follow-up to an abnormal newborn screen for Fabry disease

 

This test is not useful for patients undergoing a workup 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

This test provides diagnostic testing for male patients with positive newborn screen results, positive family history, or clinical signs and symptoms suspicious for Fabry disease.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test provides diagnostic testing for male patients with positive newborn screen results, positive family history, or clinical signs and symptoms suspicious for Fabry disease.

Testing Algorithm

The following algorithms are available:

-Fabry Disease Diagnostic Testing Algorithm

-Fabry Disease: Newborn Screen-Positive Follow-up

 

For more information, see Newborn Screening Act Sheet Fabry Disease: Decreased Alpha-Galactosidase A

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Name
A short description of the method used to perform the test

Fluorometric Enzyme Assay

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Alpha-Galactosidase, BS

Aliases
Lists additional common names for a test, as an aid in searching

a-galactosidase A

Alpha Galactosidase

Anderson-Fabry Disease

Fabry Disease

Fabry's Disease

Galactosidase, Alpha

GLA Deficiency

AGA

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test provides diagnostic testing for male patients with positive newborn screen results, positive family history, or clinical signs and symptoms suspicious for Fabry disease.

Testing Algorithm

The following algorithms are available:

-Fabry Disease Diagnostic Testing Algorithm

-Fabry Disease: Newborn Screen-Positive Follow-up

 

For more information, see Newborn Screening Act Sheet Fabry Disease: Decreased Alpha-Galactosidase A

Specimen Type
Describes the specimen type validated for testing

Whole blood

Ordering Guidance

If testing 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.

 

This test is not suitable for carrier detection in female patients. Molecular testing is recommended for diagnosis in female patients; order FABRZ / Fabry Disease, Full Gene Analysis, Varies.

Additional Testing Requirements

Additional studies including molecular genetic analysis of the GLA gene (FABRZ / Fabry Disease, Full Gene Analysis, Varies) are recommended to detect carriers.

Necessary Information

Provide a reason for testing with each specimen.

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Card-Blood Spot Collection (Filter Paper) (T493)

Container/Tube:

Preferred: Blood spot collection card

Acceptable: PerkinElmer 226 (formerly Ahlstrom 226) filter paper and Whatman Protein Saver 903 paper

Specimen Volume: 2 blood spots

Collection Instructions:

1. Do not use device or capillary tube containing EDTA to collect specimen.

2. An alternative blood collection option for a patient 1 year of age or older is a fingerstick. For infants younger than 1 year, a heel stick should be used. See Dried Blood Spot Collection Tutorial for how to collect blood spots via fingerstick: 

3. Let blood dry on the filter paper at ambient temperature in a horizontal position for a minimum of 3 hours.

4. Do not expose specimen to heat or direct sunlight.

5. Do not stack wet specimens.

6. Keep specimen dry.

Additional Information:

1. For collection instructions, see Blood Spot Collection Instructions

2. For collection instructions in Spanish, see Blood Spot Collection Card-Spanish Instructions (T777)

3. For collection instructions in Chinese, see Blood Spot Collection Card-Chinese Instructions (T800)

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

1 Blood spot

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Shows serum rings Multiple layers 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 Ambient (preferred) 90 days FILTER PAPER
Frozen 90 days FILTER PAPER
Refrigerated 90 days FILTER PAPER

Useful For
Suggests clinical disorders or settings where the test may be helpful

Diagnosis of Fabry disease in male patients using blood spot specimens

 

Verifying abnormal serum alpha-galactosidase results in male patients with a clinical presentation suggestive of Fabry disease

 

Follow-up to an abnormal newborn screen for Fabry disease

 

This test is not useful for patients undergoing a workup 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

This test provides diagnostic testing for male patients with positive newborn screen results, positive family history, or clinical signs and symptoms suspicious for Fabry disease.

Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.

This test provides diagnostic testing for male patients with positive newborn screen results, positive family history, or clinical signs and symptoms suspicious for Fabry disease.

Testing Algorithm

The following algorithms are available:

-Fabry Disease Diagnostic Testing Algorithm

-Fabry Disease: Newborn Screen-Positive Follow-up

 

For more information, see Newborn Screening Act Sheet Fabry Disease: Decreased Alpha-Galactosidase A

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, the kidney, heart, and brain. Variants within the GLA gene cause Fabry disease with severity and symptom onset 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 renal involvement leading to kidney failure (formerly end-stage renal disease) 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.

 

Measurement of alpha-Gal A in blood spots, leukocytes (AGAW / Alpha-Galactosidase, Leukocytes), or serum (AGAS / Alpha-Galactosidase, Serum) can reliably diagnose classic or variant Fabry disease in males. 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 kidney failure but without the pain or skin lesions; a cardiac variant typically presenting in the sixth to eighth decade with left ventricular hypertrophy, cardiomyopathy and arrhythmia, and proteinuria, but without kidney failure; and a cerebrovascular variant presenting as stroke or transient ischemic attack. The variant forms of Fabry disease may be underdiagnosed. Molecular genetic analysis of the GLA gene (FABRZ / Fabry Disease, Full Gene Analysis, Varies) allows for confirmation of a diagnosis of classic of variant Fabry disease in affected male patients with reduced alpha-Gal A activity.

 

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 as the most appropriate diagnostic test to detect asymptomatic or symptomatic female carriers.

 

The biomarkers globotriaosylsphingosine (LGB3S / Globotriaosylsphingosine, Serum) and ceramide trihexosides (CTSU / Ceramide Trihexosides and Sulfatides, Random, Urine) may be elevated in patients with Fabry disease and can also be used in follow up of absent or reduced alpha-Gal A activity in both male and female patients.

 

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.

 

Molecular genetic testing is the recommended diagnostic test for 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.

Males: > or =1.2 nmol/mL/hour

Females: > or =2.8 nmol/mL/hour

An interpretive report will be provided.

Interpretation
Provides information to assist in interpretation of the test results

In male patients, results less than 1.2 nmol/mL/hour in properly submitted specimens are consistent with Fabry disease. Normal results (> or =1.2 nmol/mL/hour) are not consistent with Fabry disease.

 

In female patients, normal results (> or =2.8 nmol/mL/hour) in properly submitted specimens are typically not consistent with carrier status for Fabry disease; however, enzyme analysis, in general, is not sufficiently sensitive to detect all carriers. Because a carrier range has not been established in females, molecular genetic analysis of the GLA gene (FABRZ / Fabry Disease, Full Gene Analysis, Varies) should be considered when alpha-galactosidase A activity is less than 2.9 nmol/mL/hour, or if clinically indicated.

 

Pseudodeficiency results in low measured alpha-galactosidase A activity but is not consistent with Fabry disease; FABRZ / Fabry Disease, Full Gene Analysis, Varies should be performed to resolve the clinical question.

 

See Fabry Disease Diagnostic Testing Algorithm

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Individuals with pseudodeficiency alleles can show reduced alpha-galactosidase A enzyme activity with this assay.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. 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 January 5, 2022. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225546984

2. Matern D, Gavrilov D, Oglesbee D, et al: Newborn screening for lysosomal storage disorders. Semin Perinatol. 2015 Apr;39(3):206-216

3. Mehta A, Hughes DA: Fabry Disease. In: Pagon RA, Adam MP, Ardinger HH, et al: eds. GeneReviews [Internet]. University of Washington, Seattle; 2002. Updated January 5, 2017. Accessed January 05, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1292/

4. 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

Special Instructions
Library of PDFs including pertinent information and forms related to the test

Method Description
Describes how the test is performed and provides a method-specific reference

Whole blood is collected on grade 903 (Whatman) filter paper. A one-eighth inch (3-mm) disk is punched out of the dried blood spot into a 96-well plate. An elution liquid/inhibitor, N-acetyl-D-galactosamine, and 4-methylumbelliferyl-alpha-D-galactopyranoside in citrate-phosphate buffer as the substrate are added. After the incubation period, the liquid from the plate is manually transferred to a second 96-well plate. Stop buffer (150 mM EDTA) is added to all wells. A set of calibration standards are added to every plate and are derived from 4-methylumbelliferone (4-MU) that is serially diluted manually in the plate with the highest calibrator being equivalent to an enzyme activity of 12.2 nmol/mL/hour. The plate is then read on the spectrofluorometer. Fluorescence readings for duplicate wells are averaged and the average fluorescence is used to calculate the enzyme activity result.(Poeppl AG, Murray GJ, Medin JA: Enhanced filter paper enzyme assay for high-throughput population screening for Fabry disease. Anal Biochem. 2005 Feb;337(1):161-163; Cowan T, Pasquali M: Laboratory Investigations of Inborn Errors of Metabolism. In: Sarafoglou K, Hoffman GF, Roth KS eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

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.

Thursday

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.

8 to 15 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

1 year

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

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 Regional Manager. 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. This test 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.

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
AGABS Alpha-Galactosidase, BS 55908-8
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.
50883 Specimen 31208-2
50884 Specimen ID 57723-9
50885 Source 31208-2
50886 Order Date 82785-7
50887 Reason For Referral 42349-1
50888 Method 85069-3
50889 Alpha-Galactosidase, BS 55908-8
50890 Interpretation 59462-2
50891 Amendment 48767-8
50892 Reviewed By 18771-6
50893 Release Date 82772-5

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | Create a PDF

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports