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Test ID GBAW Beta-Glucosidase, Leukocytes


Ordering Guidance


This test is preferred for diagnostic testing but does not reliably detect carriers. For carrier detection, order GBAZ / Gaucher Disease, Full Gene Analysis, Varies or CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies (specify GBA Gene List ID IEMCP-M4F13T). Call 800-533-1710 to discuss testing options.



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


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 specimen in whole blood original tube. Do not aliquot.


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.

Useful For

Diagnosis of Gaucher disease

 

This test is not intended for carrier detection.

Method Name

Flow Injection Analysis-Tandem Mass Spectrometry

Reporting Name

Beta-Glucosidase, Leukocytes

Specimen Type

Whole Blood ACD

Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Whole Blood ACD Refrigerated (preferred) 6 days
  Ambient  6 days

Clinical Information

Gaucher disease (GD) is an autosomal recessive lysosomal storage disorder caused by reduced or absent acid beta-glucosidase (glucocerebrosidase) enzyme activity resulting in accumulation of glucosylceramide (glucocerebroside) and glucopsychosine (glucosylsphingosine) in the lysosomes. This interferes with the normal functioning of cells and leads to clinical abnormalities characteristic of the disease.

 

While clinical features and severity of symptoms are widely variable within Gaucher disease, common features include abnormal blood parameters such as decreased red blood cells (anemia) and/or platelets (thrombocytopenia), bone disease, and hepatosplenomegaly. Three clinical subtypes have been identified based on the presence and progression of central nervous system (CNS) involvement. Type 1 is the most common type, representing 95% of all cases, and is generally characterized by bone disease, hepatosplenomegaly, anemia and thrombocytopenia, coagulation abnormalities, lung disease, and no CNS involvement. Type 2 or acute neuronopathic (GD2), typically has a very severe progression with onset in the first 2 years of life including neurologic disease, hepatosplenomegaly, and lung disease, with death usually between 2 and 4 years due to lung failure. Individuals with type 3 or chronic neuronopathic (GD3) may have onset prior to 2 years of age, but the progression is not as severe, and they may survive into the third and fourth decade. Finally, within the spectrum, there is a perinatal lethal form associated with skin abnormalities and nonimmune hydrops fetalis and a cardiovascular form presenting with calcification of the aortic and mitral valves, mild splenomegaly, and corneal opacities.

 

Treatment is available in the form of enzyme replacement therapy (ERT), substrate reduction therapy, and chaperone therapy for types 1 and 3. Individuals with type 3 may benefit from bone marrow transplantation. Currently, only supportive therapy is available for type 2. Emerging therapies currently listed at Clinicaltrials.gov include gene therapy and in utero ERT.

 

The incidence of type 1 ranges from 1 in 20,000 to 200,000 in the general population, but it is much more frequent among Ashkenazi Jewish population with an incidence between 1 in 400 and 900. Types 2 and 3 both have an incidence of approximately 1 in 100,000 in the general population.

 

A diagnostic workup for Gaucher disease may demonstrate the characteristic finding of "Gaucher cells" on bone marrow examination. Significantly reduced or absent enzyme activity of acid beta-glucosidase along with elevation of the biomarker, glucopsychosine (GPSY / Glucopsychosine, Blood Spot; GPSYP / Glucopsychosine, Plasma; GPSYW / Glucopsychosine, Blood) is diagnostic. Molecular analysis of the GBA gene allows for detection of disease-causing variants in affected patients (GBAZ / Gaucher Disease, Full Gene Analysis, Varies or CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies [specify GBA Gene List ID IEMCP-M4F13T]).

Reference Values

≥3.53 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 beta-glucosidase enzyme levels.

Interpretation

Individuals affected with Gaucher disease will have enzyme levels less than 3.53 nmol/h/mg protein. In our experience some carriers will also have less than 3.53 nmol/h/mg protein activity.

Clinical Reference

1. Martins AM, Valadares ER, Porta G, et al: Recommendations on diagnosis, treatment, and monitoring for Gaucher disease. J Pediatr. 2009 Oct;155(4 Suppl):S10-S18

2. Daykin EC, Ryan E, Sidransky E: Diagnosing neuronopathic Gaucher disease: New considerations and challenges in assigning Gaucher phenotypes. Mol Genet Metab. 2021 Feb;132(2):49-58. doi: 10.1016/j.ymgme.2021.01.002

3. Pastores GM, Hughes DA: Gaucher disease. In: Adam MP, Ardinger HH, Pagon RA, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2000. Updated June 21, 2018. Accessed March 1, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1269/

4. Weinreb NJ, Andersson HC, Banikazemi M, et al: Prevalence of type 1 Gaucher disease in the United States. Arch Intern Med. 2008 Feb;168:326-328

5. 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 Aug;118(4):304-309

Day(s) Performed

Preanalytical processing: Monday through Saturday

Testing performed: Monday, Wednesday

Report Available

5 to 9 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 US Food and Drug Administration.

CPT Code Information

82963

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GBAW Beta-Glucosidase, Leukocytes 32540-7

 

Result ID Test Result Name Result LOINC Value
606273 Beta-Glucosidase, Leukocytes 32540-7
606274 Interpretation 59462-2
606275 Reviewed By 18771-6