Test Id : BGA
Beta-Galactosidase, Leukocytes
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Beta-galactosidase enzyme is deficient in the following conditions: GM1 gangliosidosis, Morquio syndrome B, and galactosialidosis.
Careful review of clinical findings will help distinguish between GM1 gangliosidosis and Morquio syndrome type B.
A diagnosis of galactosialidosis must be additionally demonstrated by a deficiency of neuraminidase.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For information see Lysosomal Disorders Diagnostic Algorithm, Part 1
Method Name
A short description of the method used to perform the test
Fluorometric
NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.
Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test
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
CTSA Deficiency
B-Galactosidase
beta-galactosidase
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For information see Lysosomal Disorders Diagnostic Algorithm, Part 1
Specimen Type
Describes the specimen type validated for testing
Whole Blood ACD
Shipping Instructions
For optimal isolation of leukocytes, it is recommended the specimen arrive refrigerated within 6 days of collection to be stabilized. Collect specimen only Monday through Thursday and not the day before a holiday. Specimen should be collected and packaged as close to shipping time as possible.
Necessary Information
Provide a reason for testing with each specimen.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Container/Tube:
Preferred: Yellow top (ACD solution B)
Acceptable: Yellow top (ACD solution A)
Specimen Volume: 6 mL
Collection Instructions: Send specimen in original tube. Do not aliquot.
Special Instructions
Library of PDFs including pertinent information and forms related to the test
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.
Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the testing laboratory. The minimum volume is sufficient for one attempt at testing.
5 mL
Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected
| Gross hemolysis | Reject |
Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Whole Blood ACD | Refrigerated (preferred) | 6 days | YELLOW TOP/ACD |
| Ambient | 6 days | YELLOW TOP/ACD |
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Beta-galactosidase enzyme is deficient in the following conditions: GM1 gangliosidosis, Morquio syndrome B, and galactosialidosis.
Careful review of clinical findings will help distinguish between GM1 gangliosidosis and Morquio syndrome type B.
A diagnosis of galactosialidosis must be additionally demonstrated by a deficiency of neuraminidase.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For information see Lysosomal Disorders Diagnostic Algorithm, Part 1
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. Isolated deficiency of this enzyme can be expressed clinically as 2 different diseases, GM1 gangliosidosis (GM1) and Morquio syndrome B (MPS IVB: mucopolysaccharidosis IVB), or in some patients as a disease that combines the skeletal features of MPS IVB and neurologic features of GM1. Galactosialidosis is also associated with a deficiency of beta-galactosidase but in conjunction with neuraminidase secondary to a defect in protective protein cathepsin A (CTSA). Enzymatic testing is not reliable for carrier detection of these conditions.
GM1 gangliosidosis is autosomal recessive and absent or reduced beta-galactosidase enzyme activity leads to the accumulation of GM1 gangliosides, oligosaccharides, and keratan sulfate. The disorder can be classified into 3 subtypes that vary with respect 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 or regression and a slower clinical course. 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.
In MPS IVB, reduced or absent beta-galactosidase activity leads to the accumulation of glycosaminoglycans (GAG), specifically keratan sulfate, in cells, tissues, and organs interfering with their normal function. MPS IVB typically manifests as a systemic skeletal disorder with variable severity ranging from early severe disease to a later onset attenuated form. Virtually all patients have dysostosis multiplex and short stature along with other symptoms that may include coarse facies, hepatosplenomegaly, hoarse voice, stiff joints, and cardiac disease but no neurological involvement.
Galactosialidosis (GS) is an autosomal recessive lysosomal storage disease caused by variants in CTSA resulting in a combined deficiency of the enzymes beta-galactosidase and neuraminidase. The disorder can be classified into 3 subtypes that vary with respect to age of onset and clinical presentation. Typical clinical presentation includes coarse facial features, cherry-red spots, and skeletal dysplasia. The early infantile form is associated with fetal hydrops, visceromegaly, 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 majority of individuals with the juvenile/adult form of GS are of Japanese ancestry and develop symptoms after 4 years of age, which include neurologic degeneration, ataxia, and angiokeratomas.
Patients with mucolipidosis II/III (I-cell disease) may also demonstrate deficiency of beta-galactosidase in leukocytes, in addition to deficiency of other hydrolases. I-cell disease is an autosomal recessive lysosomal storage disorder resulting in impaired transport and phosphorylation of newly synthesized lysosomal proteins to the lysosome due to deficiency of N-acetylglucosamine 1-phosphotransferase (GlcNAc). Characteristic clinical features include short stature, skeletal and cardiac abnormalities, and developmental delay. Measurement of beta-galactosidase activity is not the preferred diagnostic test for I-cell disease but may be included in the testing strategy.
A diagnostic workup in an individual with GM1 gangliosidosis, MPS IVB, or GS typically demonstrates decreased beta-galactosidase enzyme activity in leukocytes or fibroblasts; however, additional testing and consideration of the patient's clinical findings are necessary to differentiate between these conditions. Follow-up testing may include LSDS / Lysosomal Storage Disorders Screen, Random, Urine, which analyzes mucopolysaccharides, oligosaccharides, ceramide trihexosides, and sulfatides to help differentiate between the 3 conditions and guide physicians in choosing the best confirmatory molecular testing option, which may include LSDGP / Lysosomal Storage Disease Gene Panel, Varies.
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.
> or =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.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test does not differentiate between GM1 gangliosiosis, Morquio B, and galactosialidosis.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Suzuki Y, Nanba E, Matsuda J, Higaki K, Oshima A. Beta-galactosidase deficiency (beta-galactosidosis): GM1 gangliosidosis and Morquio B disease. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed June 9, 2025. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225547263
2. d'Azzo A, Andria G, Bonten E, Annunziata I. Galactosialidosis. In: Valle DL, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, et al, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed June 9, 2025. Available at https://ommbid.mhmedical.com/content.aspx?sectionid=225547663
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;1812(7):782-790. doi:10.1016/j.bbadis.2011.03.018
4. Kingma SDK, Ceulemans B, Kenis S, Jonckheere AI. Are GMI gangliosidosis and Morquio type B two different disorders or part of one phenotypic spectrum?. JIMD Rep. 2021;59(1):90-103. doi:10.1002/jmd2.12204
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.(Ho MW, O'Brien JS. Differential effect of chloride ions on galactosidase isoenzymes: a method for separate assay. Clin Chim Acta. 1971;32[3]:443-450; Gehler J, Cantz M, Tolksdorf M, Spranger J, Gilbert E, Drube H. Mucopolysaccharidosis. VII. Beta-glucuronidase deficiency. Humangenetik. 1974;23[2]:149-158. doi:10.1007/BF00282212; Cowan T, Pasquali M. Laboratory Investigations of Inborn Errors of Metabolism. In: Sarafoglou K, Hoffman GF, Roth KS, eds. Pediatric Endocrinology and Inborn Errors of Metabolism. 2nd ed. McGraw-Hill; 2017:1139-1158)
PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information
Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.
Preanalytical processing: Monday through Sunday
Assay performed: Tuesday
Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.
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
Indicates the location of the laboratory that performs the test
Fees :
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.
- Authorized users can sign in to Test Prices for detailed fee information.
- Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
- Prospective clients should contact their account representative. For assistance, contact Customer Service.
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 instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
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 Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
CPT codes are provided by the performing laboratory.
CPT codes are provided by the performing laboratory.
82657
LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.
| Test Id | Test Order Name | Order LOINC Value |
|---|---|---|
| BGA | Beta-Galactosidase, Leukocytes | 24061-4 |
| Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
|---|---|---|
| 8486 | Beta-Galactosidase, Leukocytes | 24061-4 |
| 34907 | Reviewed By | 18771-6 |
| 34979 | Interpretation (BGA) | 59462-2 |