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Test ID: FABRZ Fabry Disease, Full Gene Analysis

Useful For

Confirmation of a diagnosis of classic or variant Fabry disease in affected males with reduced alpha-Gal A enzyme activity

 

Carrier or diagnostic testing for asymptomatic or symptomatic females, respectively

Testing Algorithm

The following algorithms are available in Special Instructions:

-Fabry Disease: Newborn Screen-Positive Follow-up

-Fabry Disease Testing Algorithm

Method Name

Polymerase Chain Reaction (PCR) Amplification/DNA sequencing

Reporting Name

Fabry Disease Full Gene Analysis

Specimen Type

Varies


Specimen Required


Specimen preferred to arrive within 96 hours of draw.

 

Submit only 1 of the following specimens:

 

Preferred:

Specimen Type: Whole blood

Container/Tube:

Preferred: Lavender top (EDTA) tube or yellow top (ACD) tube

Acceptable: Any anticoagulant

Specimen Volume: 3 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send specimen in original tube.

Specimen Stability Information: Ambient (preferred)/Refrigerated

 

Acceptable:

Specimen Type: Blood spot

Container/Tube:

Preferred: Collection card (Whatman Protein Saver 903 Paper)

Acceptable: Ahlstrom 226 filter paper, or Blood Spot Collection Card (T493)

Specimen Volume: 2 to 5 Blood spots on collection card (Whatman Protein Saver 903 Paper; Ahlstrom 226 filter paper; or Blood Spot Collection Card, T493)

Collection Instructions:

1. An alternative blood collection option for a patient >1 year of age is finger stick.

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

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

4. Do not stack wet specimens.

5. Keep specimen dry.

Specimen Stability Information: Ambient (preferred)/Refrigerated


Specimen Minimum Volume

Blood: 1 mL; Blood Spots: 5 punches-3 mm diameter

Specimen Stability Information

Specimen Type Temperature Time
Varies Varies

Clinical Information

Fabry disease is an X-linked recessive disorder with an incidence of approximately 1 in 50,000 males. Symptoms result from a deficiency of the enzyme alpha-galactosidase A (alpha-Gal A). Reduced alpha-Gal A activity results in accumulation of glycosphingolipids in the lysosomes of both peripheral and visceral tissues.

 

Severity and onset of symptoms are dependent on the residual alpha-Gal A activity. Males with <1% alpha-Gal A activity have the classic form of Fabry disease. Symptoms can appear in childhood or adolescence and usually include acroparesthesias (pain crises), multiple angiokeratomas, reduced or absent sweating, and corneal opacity. By middle age, most patients develop renal insufficiency leading to end-stage renal disease, as well as cardiac and cerebrovascular disease. Males with >1% alpha-Gal A activity may present with a variant form of Fabry disease. The renal variant generally has onset of symptoms in the third decade. The most prominent feature in this form is renal insufficiency and, ultimately, end-stage renal disease. Individuals with the renal variant may or may not have other symptoms of classic Fabry disease. Individuals with the cardiac variant are often asymptomatic until they present with cardiac findings such as cardiomyopathy or mitral insufficiency later in life. The cardiac variant is not associated with renal failure.

 

Female carriers of Fabry disease can have clinical presentations ranging from asymptomatic to severe. Measurement of alpha-Gal A activity is not generally useful for identifying carriers of Fabry disease, as many of these individuals have normal levels of alpha-Gal A.

 

Mutations in the GLA gene result in deficiency of alpha-Gal A. Most of the mutations identified to date are family specific. Full sequencing of the GLA gene identifies over 98% of the sequence variants in the coding region and splice junctions. In addition, our assay detects the intron 4 mutation common in the Taiwanese population.(1)

 

See Fabry Disease: Newborn Screen-Positive Follow-up algorithm and Fabry Disease Testing Algorithm in Special Instructions.

Reference Values

An interpretive report will be provided.

Interpretation

All detected alterations will be evaluated according to the American College of Medical Genetics and Genomics (AMCG) recommendations.(2) Variants will be classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

Clinical Reference

1. Hwu WL, Chien YH, Lee NC, et al: Newborn screening for Fabry disease in Taiwan reveals a high incidence of the later-onset GLA mutation c.936+919G>A). Hum Mutat 2009:30(10):1397-1405

2. Richards S, Aziz N, Bale S, et al: Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med 2015 May;17(5):405-424

3. Germain DP: Fabry disease. Orphanet J Rare Dis. 2010 Nov 22;5:30

4 Wang RY, Lelis A, Mirocha J, Wilcox WR: Heterozygous Fabry women are not just carriers, but have a significant burden of disease and impaired quality of life. Genet Med 2007 Jan;9(1):34-35

Day(s) and Time(s) Performed

Performed weekly, Varies

Analytic Time

14 days

Test Classification

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 U.S. Food and Drug Administration.

CPT Code Information

81405-GLA (galactosidase, alpha) (eg, Fabry disease), full gene sequence

LOINC Code Information

Result ID Test Result Name Result LOINC Value
53894 Result Summary 50397-9
53895 Result In Process
53896 Interpretation In Process
53897 Additional Information 48767-8
53898 Specimen In Process
53899 Source 31208-2
53900 Released By No LOINC Needed

Forms

1. Molecular Genetics: Biochemical Disorders Patient Information (T527) in Special Instructions

2. 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 (T576) is available in Special Instructions.

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-inherited-molecular