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Test ID: GPSYP Glucopsychosine, Plasma


Ordering Guidance


This test is also available as a part of a panel; see HSMP / Hepatosplenomegaly Panel, Plasma. If this test (GPSYP) is ordered with either CTXP / Cerebrotendinous Xanthomatosis, Plasma or OXNP / Oxysterols, Plasma, the individual tests will be canceled and HSMP ordered.



Specimen Required


Collection Container/Tube:

Preferred: Lavender top (EDTA)

Acceptable: Green top (sodium heparin, lithium heparin), yellow top (ACD B)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.3 mL

Collection Instructions:

1. Centrifuge at 4° C, if possible

2. Aliquot plasma into plastic vial. Do not disturb or transfer the buffy coat layer.

3. Send frozen


Forms

1. Biochemical Genetics Patient Information (T602)

2. If not ordering electronically, complete, print, and send a Biochemical Genetics Test Request (T798) with the specimen.

Useful For

Second-tier test when newborn screening results with reduced beta-glucosidase (GBA) activity are identified

 

Diagnosis and monitoring of patients with Gaucher disease using plasma specimens

 

Supporting a biochemical diagnosis of Gaucher disease

 

Monitoring a patient's response to treatment

 

This test is not useful for identifying carriers of GBA variants.

Method Name

Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

Glucopsychosine, P

Specimen Type

Plasma

Specimen Minimum Volume

0.25 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Plasma Frozen 65 days

Clinical Information

Gaucher disease is an autosomal recessive lysosomal storage disorder caused by a deficiency of the enzyme, beta-glucosidase, which facilitates the lysosomal degradation of glucosylceramide (glucocerebroside) and glucopsychosine (glucosylsphingosine: lyso-GL1). Gaucher disease is caused by mutations in the GBA gene and presents with a markedly variable phenotype, ranging from a perinatal lethal disorder to mildly symptomatic. It has historically been categorized into 3 types (GD1, GD2 and GD3) based on the presence and progression of neuropathic features. All types of Gaucher disease include hepatosplenomegaly and hematological abnormalities.

 

Gaucher disease type I is the most common, representing more than 90% of cases. It is generally characterized by bone disease, hepatosplenomegaly, anemia and thrombocytopenia, coagulation abnormalities, lung disease, but no central nervous system involvement. Gaucher disease types II and III are characterized by the presence of primary neurologic disease, although in practice, assigning a type in infancy can sometimes be challenging due to overlapping clinical features. In addition, type II typically presents with limited psychomotor development, hepatosplenomegaly, and lung disease, resulting in death usually between 2 and 4 years of age. Individuals with Gaucher disease type III may present prior to 2 years of age, but the progression is not as rapid, and patients may survive into the third and fourth decade. Additional subtypes of Gaucher disease include 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, corneal opacities, and gaze impairment.

 

Treatment is available in the form of enzyme replacement therapy and substrate reduction therapy for types I and III. These treatment options have generally made bone marrow transplantation obsolete. Currently, only supportive therapy is available for type II because of the inability of enzyme provided by replacement therapy to cross the blood-brain barrier.

 

The incidence of Gaucher disease type I ranges from 1 in 30,000 to 1 in 100,000 in the general population but is much more frequent among the Ashkenazi Jewish population with an incidence of approximately 1 in 900. Types II and III 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, other hematologic abnormalities, and hepatosplenomegaly. The diagnosis can be confirmed by the demonstration of reduced or absent acid beta-glucosidase activity in leukocytes (GBAW / Beta-Glucosidase, Leukocytes), or dried blood spots (PLSD / Lysosomal and Peroxisomal Storage Disorders Screen, Blood Spot) and molecular genetic analysis of the GBA gene (GBAZ / Gaucher Disease, Full Gene Analysis, Varies). Lyso-GL1 is a sensitive and specific biomarker for Gaucher disease, and an elevation of lyso GL-1 in blood supports the diagnosis. Lyso GL-1 has also been shown to be helpful in monitoring mildly symptomatic individuals for disease progression and in determining treatment response.

Reference Values

GLUCOPSYCHOSINE

Cutoff: ≤0.003 nmol/mL

Interpretation

An elevation of glucopsychosine (glucosylsphingosine: lyso-GL1) is indicative of Gaucher disease.

Clinical Reference

1. Pastores GM, Hughes DA: Gaucher disease. In: Adam MP, Everman DB, Mirzaa GM, et al, eds. GeneReviews [Internet]. University of Washington, Seattle; 2000. Updated June 21, 2018. Accessed December 28, 2022. Available at www.ncbi.nlm.nih.gov/books/NBK1269/

2. Kaplan P, Baris H, De Meirleir L, et al: Revised recommendations for the management of Gaucher disease in children. Eur J Pediatr. 2013 Apr;172(4):447-458

3. Grabowski GA, Petsko GA, Kolodny EH: : Gaucher disease. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill Education; 2019. Accessed December 28, 2022. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225546056&bookid=2709

4. Murugesan V, Chuan WL, Liu J, et al: Glucosylsphingosine is a key biomarker of Gaucher disease. Am J Hematol. 2016 Nov;91(11)1082-1089

5. Saville JT, McDermott BK, Chin SJ, Fletcher JM, Fuller M: Expanding the clinical utility of glucosylsphingosine for Gaucher disease. J Inherit Metab Dis. 2020 May;43(3):558-563

6. 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. Epub 2021 Jan 9. PMID: 33483255; PMCID: PMC7884077

Day(s) Performed

Tuesday, Thursday

Report Available

3 to 7 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

82542

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GPSYP Glucopsychosine, P 92750-9

 

Result ID Test Result Name Result LOINC Value
BA4375 Interpretation (GPSYP) 59462-2
BA4373 Glucopsychosine 92750-9
BA4374 Reviewed By 18771-6
Mayo Clinic Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

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