TEST CATALOG ORDERING & RESULTS SPECIMEN HANDLING CUSTOMER SERVICE EDUCATION & INSIGHTS
Test Catalog

Test ID: GBAZ    
Gaucher Disease, Full Gene Analysis, Varies

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

Confirmation of a diagnosis of Gaucher disease

 

Carrier screening in cases where there is a family history of Gaucher disease, but an affected individual is not available for testing or disease-causing alterations have not been identified

Genetics Test Information Provides information that may help with selection of the correct genetic test or proper submission of the test request

Testing includes full gene sequencing of the GBA gene.

 

Risk alleles for Parkinson disease with no known beta-glucocerebrosidase enzyme reduction or Gaucher disease association will only be reported in patients over 18 years old unless otherwise requested.

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

If a skin biopsy is received, fibroblast culture and cryopreservation for biochemical studies will be added at an additional charge.

 

See Newborn Screen Follow-up for Gaucher Disease in Special Instructions.

 

For more information, see Newborn Screening Act Sheet Gaucher Disease: Decreased Acid Beta-Glucosidase in Special Instructions.

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Gaucher disease is a relatively rare lysosomal storage disorder resulting from a deficiency of acid beta-glucocerebrosidase. Reduced or absent activity of this enzyme results in accumulation of its substrate in lysosomes, interfering with cell function. There are 3 major types of Gaucher disease: nonneuropathic (type 1), acute neuropathic (type 2), and subacute neuropathic (type 3). In addition, there are 2 rare presentations of Gaucher disease: 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. Gaucher disease demonstrates large clinical variability, even within families.

 

Type 1 accounts for over 95% of all cases of Gaucher disease and is the presentation commonly found among Ashkenazi Jewish patients. The carrier rate of Gaucher disease in the Ashkenazi Jewish population is 1:18. There is a broad spectrum of disease in type 1 Gaucher disease, with some patients exhibiting severe symptoms and others very mild disease. Type 1 disease does not involve nervous system dysfunction; patients may display anemia, low blood platelet levels, massively enlarged livers and spleens, lung infiltration, and extensive skeletal disease. Type 2 is characterized by early-onset neurologic disease with rapid progression to death by 2 to 4 years of age. Type 3 may have early onset of symptoms, but generally a slower disease progression than type 2.

 

Alterations in the GBA gene cause the clinical manifestations of Gaucher disease. Over 250 variants have been reported to date. The N370S and L444P alterations have the highest prevalence in most populations. N370S is associated with type 1 Gaucher disease, and individuals with at least 1 copy of this alteration do not develop the primary neurologic disease seen in types 2 and 3. Conversely, L444P is associated with neurologic disease.

 

Alterations in the GBA gene have also been reported to cause an increased risk for Parkinson disease. Alterations associated with Parkinson disease, but not Gaucher disease, are not routinely reported for patients under the age of 18, but are available upon request.

 

For carrier screening of the general population, the recommended test is GAUP / Gaucher Disease, Mutation Analysis, GBA, Varies, which tests for the 8 most common GBA alterations. For diagnostic testing (ie, potentially affected individuals), enzyme testing (GBAW / Beta-Glucosidase, Leukocytes) should be performed prior to variant analysis. In individuals with abnormal enzyme activity and 1 or no variants detected by a panel of common alterations, sequence analysis of the GBA gene should be utilized to detect private variants. Additionally, measurement of the glucopsychosine biomarker can aid in diagnosis and ongoing therapeutic monitoring (GPSY / Glucopsychosine, Blood Spot).

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.

An interpretive report will be provided.

Interpretation Provides information to assist in interpretation of the test results

All detected alterations are evaluated according to American College of Medical Genetics and Genomics (ACMG) recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.

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

A small percentage of individuals who are carriers or have a diagnosis of Gaucher disease may have a variant that is not identified by this method (eg, large genomic deletions, promoter alterations). The absence of a variant, therefore, does not eliminate the possibility of positive carrier status or the diagnosis of Gaucher disease. For carrier testing, it is important to first document the presence of a GBA gene variant in an affected family member.

 

In some cases, DNA alterations of undetermined significance may be identified.

 

Rare alterations exist that could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, additional testing should be considered.

 

Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Errors in the interpretation of results may occur if information given is inaccurate or incomplete.

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

1. 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

2. Guggenbuhl P, Grosbois B, Chales G: Gaucher disease. Joint Bone Spine. 2008 Mar;75(2):116-124

3. Hruska KS, LaMarca ME, Scott CR, Sidransky E: Gaucher disease: mutation and polymorphism spectrum in the glucocerebrosidase gene (GBA). Hum Mutat. 2008 May;29(5):567-583

4. O'Regan G, deSouza RM, Balestrino R, Schapira AH: Glucocerebrosidase mutations in Parkinson disease. J Parkinsons Dis. 2017;7(3):411-422

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