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Order Code LABGOR, AGABS Alpha-Galactosidase, Blood Spot

Reporting Name

Alpha-Galactosidase, BS

Useful For

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.

Testing Algorithm

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.

 

The following algorithms are available:

-Fabry Disease Diagnostic Testing Algorithm

-Fabry Disease: Newborn Screen-Positive Follow-up

 

If the patient has abnormal newborn screening results for Fabry disease. Refer to the appropriate ACMG Newborn Screening ACT Sheet.(1)

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Specimen Type

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.

 

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.



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


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 older than 1 year is a fingerstick. For detailed instructions, see How to Collect Dried Blood Spot Samples.

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)


Specimen Minimum Volume

1 Blood spot

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole blood Ambient (preferred) 90 days FILTER PAPER
  Frozen  90 days FILTER PAPER
  Refrigerated  90 days FILTER PAPER

Reference Values

Males: ≥1.2 nmol/mL/hour

Females: ≥2.8 nmol/mL/hour

An interpretive report will be provided.

Day(s) Performed

Thursday

CPT Code Information

82657

Method Description

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;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)

Reject Due To

Shows serum rings Multiple layers Reject

Method Name

Fluorometric Enzyme Assay

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.

Genetics Test Information

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.