Test ID: BGA
Beta-Galactosidase, Leukocytes
NY State Approved 
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
Diagnosis of GM1 gangliosidosis, Morquio B disease, and galactosialidosis
Genetics Test Information Provides information that may help with selection of the correct test or proper submission of the test request
Not recommended for carrier detection.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Fluorometric
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
G[M1] Gangliosidosis
Galactosidase, Beta
Generalized Gangliosidosis, G(M1)
GLB1 Deficiency
GM1 Gangliosidosis
Morquio B
Morquio Disease
Morquio Syndrome
Morquio's B
Morquio's Disease
MPS IV
MPS IVB
Mucopolysaccharidosis IVb
Cathepsin A Deficiency
Galactosialidosis
PPCA (Protective Protein/Cathepsin A) Deficiency
Protective Protein Deficiency
Protective Protein/Cathepsin A (PPCA) Deficiency
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
Specimen must arrive within 72 hours of draw to be stabilized. Draw specimen Monday through Thursday only and not the day before a holiday. Specimen should be drawn and packaged as close to shipping time as possible.
Container/Tube:
Preferred: Yellow top (ACD solution B)
Acceptable: Yellow top (ACD solution A)
Specimen Volume: 7 mL
Collection Instructions: Do not transfer blood to other containers.
Forms:
1. 1. 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 (Supply T576) is available in Special Instructions.
2. 2. If not ordering electronically, submit a Biochemical Genetics Request Form (Supply T439) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | Mild OK; Gross reject |
| Lipemia | NA |
| Icterus | NA |
| Other | NA |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Whole Blood ACD | Refrigerated (preferred) | 72 hours |
| Ambient | 72 hours |
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Beta-galactosidase is a lysosomal enzyme responsible for catalyzing the hydrolysis of gangliosides. The deficiency of this enzyme can lead to the following conditions: GM1 gangliosidosis, Morquio syndrome B, and galactosialidosis.
GM1 gangliosidosis is an autosomal recessive lysosomal storage disorder caused by reduced or absent beta-galactosidase activity. Absent or reduced activity leads to the accumulation of GM1 gangliosides, oligosaccharides, and keratan sulfate. The disorder can be classified into 3 subtypes that vary with regard to age of onset and clinical presentation. Type 1, or infantile onset, typically presents between birth and 6 months with a very rapid progression of hypotonia, dysostosis multiplex, hepatosplenomegaly, central nervous system degeneration, and death usually by 1 to 2 years. Type 2 is generally classified as late infantile or juvenile with onset between 7 months and 3 years presenting with developmental delays and a slower progression. Type 3 is an adult or chronic variant with onset between 3 and 30 years and is typically characterized by slowly progressive dementia with Parkinsonian features and dystonia. The incidence has been estimated to be 1 in 100,000 to 200,000 live births.
Mucopolysaccharidosis type IVB (MPS IVB, Morquio B) is an autosomal recessive lysosomal storage disorder caused by reduced or absent beta-galactosidase activity. The mucopolysaccharidoses are a group of disorders caused by the deficiency of any of the enzymes involved in the stepwise degradation of dermatan sulfate, heparan sulfate, keratan sulfate, or chondroitin sulfate (glycosaminoglycans; GAGs). Accumulation of GAGs (also known as mucopolysaccharides) in lysosomes interferes with normal functioning of cells, tissues, and organs. MPS IVB is caused by a reduced or absent activity of the beta-galactosidase enzyme and gives rise to the physical manifestations of the disease. Clinical features and severity of symptoms of MPS IVB are widely variable ranging from severe disease to an attenuated form, which generally presents at a later onset with a milder clinical presentation. In general, symptoms may include coarse facies, short stature, hepatosplenomegaly, hoarse voice, stiff joints, cardiac disease, but no neurological involvement. Treatment options are limited to symptomatic management.
Galactosialidosis is an autosomal recessive lysosomal storage disease associated with a combined deficiency of beta-galactosidase and neuraminidase secondary to a defect in the cathepsin A protein. The disorder can be classified into 3 subtypes that vary with regard to age of onset and clinical presentation. Typical clinical presentation is coarse facial features, cherry-red spots, or skeletal dysplasia. The early infantile form is associated with fetal hydrops, skeletal dysplasia, and early death. The late infantile form typically presents with short stature dysostosis multiplex, coarse facial features, hepatosplenomegaly, and/or heart valve problems. The juvenile/adult form is typically characterized by progressive neurologic degeneration, ataxia, and/or angiokeratomas. The incidence of the juvenile/adult form is greater in individuals with Japanese ancestry.
A diagnostic workup in an individual with GM1 gangliosidosis, Morquio B, or galactosialidosis typically demonstrates decreased beta-galactosidase enzyme activity in leukocytes and/or fibroblasts; however, enzymatic testing is not reliable to detect carriers. Individuals with galactosialidosis would also have decreased neuraminidase activity in leukocytes and/or fibroblasts in addition to decreased beta-galactosidase enzyme activity. Molecular sequence analysis of the GLB1 gene allows for detection of the disease-causing mutations in affected patients with GM1 gangliosidosis and/or Morquio B and sequencing of the CTSA gene allows for detection of disease-causing mutations in patients with galactosialidosis.
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.
>=1.56 nmol/min/mg
Interpretation Provides information to assist in interpretation of the test results
Very low enzyme activity levels are consistent with GM1 gangliosidosis and Morquio B disease. Clinical findings must be used to differentiate between those 2 diseases. The deficiency of beta-galactosidase combined with neuraminidase deficiency is characteristic of galactosialidosis.
At this time there is no known clinical significance to elevated enzyme levels.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not suitable for carrier detection.
Because beta-galactosidase is decreased in 3 clinically distinct disorders, a careful review of the clinical findings is necessary to differentiate between GM1 gangliosidosis and Morquio syndrome B. Patients with galactosialidosis will also exhibit decreased neuraminidase values in addition to decreased beta-galactosidase.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1.Suzuki Y, Sakuraba H, Oshima A: Chapter 151: Beta-galactosidase deficiency. In The Metabolic Basis of Inherited Disease. Vol 3. Eighth edition. Edited by CR Scriver, AL Beaudet, WS Sly, D Valle. New York, McGraw-Hill Book Company, 2001
2. Brunetti-Pierri N, Scaglia F: GM1 gangliosidosis: review of clinical, molecular, and therapeutic aspects. Mol Genet Metab 2008 Aug;94(4):391-396
3. Caciotti A, Garman SC, Rivera-Colon, Y, et al: GM1 gangliosidosis and Morquio B disease: an update on genetic alterations and clinical findings. Biochim Biophys Acta 2011 Jul;1812(7):782-790.
Method Description Describes how the test is performed and provides a method-specific reference
The deficiency of beta-galactosidase is demonstrable using the artificial substrate 4-methylumbelliferyl-beta-D-galactopyranoside. The enzyme hydrolyzes the artificial substrate to produce 4-methylumbelliferone, which is measured fluorometrically.(Modified from Ho MW, O'Brien JS: Differential effect of chloride ions on galactosidase isoenzymes: a method for separate assay. Clin Chim Acta 1971 May;32[3]:443-450; Gehler J, Cantz M, Tolksdorf M, et al: Mucopolysaccharidosis. VII. Beta-glucuronidase deficiency. Humangenetik 1974 July 15;23[2]:149-158)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Specimens are processed Monday through Sunday.
Assay is performed on Wednesday; varies.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
82657
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 8486 | Beta-Galactosidase, Leukocytes | 24061-4 |
| 34979 | Interpretation (BGA) | 59462-2 |
| 34907 | Reviewed By | N/A |
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