Test Id : GALE
Uridine Diphosphate-Galactose 4' Epimerase, Blood
Useful For
Suggests clinical disorders or settings where the test may be helpful
Diagnosis of uridine diphosphate-galactose 4' epimerase deficiency
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Enzymatic testing for the diagnosis of uridine diphosphate-galactose 4' epimerase deficiency.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For more information see Galactosemia Testing Algorithm.
Method Name
A short description of the method used to perform the test
Enzyme Reaction followed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
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
UDP-Galactose 4' Epimerase (GALE)
Galactosemia
Galactosemia Enzyme (verify which test)
GALE deficiency
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For more information see Galactosemia Testing Algorithm.
Specimen Type
Describes the specimen type validated for testing
Whole Blood EDTA
Ordering Guidance
This test is appropriate for diagnosis of uridine diphosphate-galactose 4' epimerase (GALE) deficiency, but it will not detect galactokinase (GALK) deficiency, galactose-1-phosphate uridyltransferase (GALT) deficiency, or galactose mutarotase (GALM) deficiency.
-To evaluate for GALK deficiency, order GALK / Galactokinase, Blood.
-To evaluate for GALT deficiency, order GALT / Galactose-1-Phosphate Uridyltransferase, Blood.
-To evaluate for GALM deficiency, order GALP / Galactose, Plasma and molecular analysis of the GALM gene.
This assay is not appropriate for monitoring dietary compliance for patients with GALE deficiency. If dietary monitoring is needed, order GAL1P / Galactose-1-Phosphate, Erythrocytes.
Necessary Information
Patient's age is required.
Biochemical Genetics Patient Information (T602) is recommended, but not required, to be filled out and sent with the specimen to aid in the interpretation of test results.
Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing
Multiple whole blood tests for galactosemia can be performed on 1 specimen. Prioritize order of testing when submitting specimens. For a list of tests that can be ordered together, see Galactosemia-Related Test List.
Container/Tube:
Preferred: Lavender top (EDTA)
Acceptable: Green top (sodium or lithium heparin) or yellow top (ACD)
Specimen Volume: 5 mL
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) is recommended.
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.
2 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 EDTA | Refrigerated (preferred) | 14 days | |
| Ambient | 6 days |
Useful For
Suggests clinical disorders or settings where the test may be helpful
Diagnosis of uridine diphosphate-galactose 4' epimerase deficiency
Genetics Test Information
Provides information that may help with selection of the correct genetic test or proper submission of the test request
Enzymatic testing for the diagnosis of uridine diphosphate-galactose 4' epimerase deficiency.
Testing Algorithm
Delineates situations when tests are added to the initial order. This includes reflex and additional tests.
For more information see Galactosemia Testing Algorithm.
Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Galactosemia is an autosomal recessive disorder that results from a deficiency of any 1 of the 4 enzymes catalyzing the conversion of galactose to glucose: galactose-1-phosphate uridyltransferase (GALT), galactokinase (GALK), uridine diphosphate galactose-4-epimerase (GALE), and galactose mutarotase (GALM).
Epimerase deficiency galactosemia can be categorized into 3 types: generalized, peripheral, and intermediate. Generalized epimerase deficiency galactosemia is rare with less than 10 cases described in the literature and results in profoundly decreased enzyme activity in all tissues, whereas peripheral epimerase deficiency galactosemia results in decreased enzyme activity in red and white blood cells, but normal enzyme activity in all other tissues. This is compared to intermediate epimerase deficiency galactosemia, which results in decreased enzyme activity in red and white blood cells and less than 50% of normal enzyme levels in other tissues.
Clinically, infants with generalized epimerase deficiency galactosemia develop symptoms such as liver and kidney dysfunction and mild cataracts when on a normal milk diet, while infants with peripheral or intermediate epimerase deficiency galactosemia do not develop any symptoms. Generalized epimerase deficiency galactosemia is treated by a galactose- and lactose-restricted diet, which can improve or prevent the symptoms of kidney and liver dysfunction and mild cataracts. Despite adequate treatment from an early age, individuals with generalized epimerase deficiency galactosemia remain at increased risk for developmental delay and intellectual disability. Unlike patients with classic galactosemia resulting from a GALT deficiency, female patients with generalized epimerase deficiency galactosemia experience normal puberty and are not at increased risk for premature ovarian failure. Based upon reports by newborn screening programs, the frequency of epimerase deficiency galactosemia in the United States ranges from approximately 1 in 6700 African American infants to 1 in 70,000 infants of European ancestry.
Galactose-1-phosphate (Gal1P) accumulates in the erythrocytes of patients with galactosemia due to either GALT or GALE deficiency or in neonates with GALM deficiency. The quantitative measurement of Gal1P (GAL1P / Galactose-1-Phosphate, Erythrocytes) is useful for monitoring compliance with dietary therapy. Gal1P is thought to be the causative factor for development of liver disease in patients with GALT or GALE deficiency. Because of this, patients should maintain low levels and be monitored on a regular basis.
Newborn screening varies from state to state and identifies potentially affected individuals by measuring total galactose (galactose and Gal1P) or determining the activity of the GALT enzyme. The diagnosis of galactosemia is established by follow-up quantitative measurement of GALT enzyme activity. If enzyme levels are normal, but an infant has an elevated Gal-1-P, then epimerase deficiency galactosemia should be considered. Molecular analysis of the GALE gene is available; order CGPH / Custom Gene Panel, Hereditary, Next-Generation Sequencing, Varies and specify Gene List ID: IEMCP- MGXGL2.
For more information see Galactosemia Testing Algorithm.
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 =3.5 nmol/h/mg of hemoglobin
Interpretation
Provides information to assist in interpretation of the test results
Results below 3.5 nmol/h/mg of hemoglobin in properly submitted specimens have different causes from carrier status for a disease-causing variant in the GALE gene (typically reduced uridine diphosphate-galactose 4' epimerase [GALE] activity close to the normal activity range) to generalized epimerase deficiency galactosemia due to biallelic disease-causing variants in the GALE gene that markedly reduce GALE activity. Further differentiation requires additional biochemical and molecular genetic analyses as well as correlation with clinical signs and symptoms.
Normal results (> or =3.5 nmol/hour/mg of hemoglobin) are not consistent with galactosemia due to GALE deficiency.
Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
The results of testing performed in erythrocytes, including analysis of enzymes, biochemical phenotyping, or galactose-1-phosphate are invalid following a transfusion.
Clinical Reference
Recommendations for in-depth reading of a clinical nature
1. Fridovich-Keil J, Bean L, He M, Schroer R. Epimerase deficiency galactosemia. In: Adam MP, Feldman J, Mirzaa GM,, et al. eds. GeneReviews [Internet]. University of Washington, Seattle; 2011. Updated March 11, 2021. Accessed September 12, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK51671/
2. Walter JH, Fridovich-Keil JL. Galactosemia. In: Valle D, Antonarakis S, Ballabio A, Beaudet AL, Mitchell GA, eds. The Online Metabolic and Molecular Bases of Inherited Disease. McGraw-Hill; 2019. Accessed September 12, 2024. Available at https://ommbid.mhmedical.com/content.aspx?bookid=2709§ionid=%20225081023
3. Timson DJ. Type IV galactosemia. Genet Med. 2019;21(6):1283-1285. doi:10.1038/s41436-018-0359-z
4. Wada Y, Kikuchi A, Arai-Ichinoi N, et al. Biallelic GALM pathogenic variants cause a novel type of galactosemia. Genet Med. 2019;21(6):1286-1294. doi:10.1038/s41436-018-0340-x
Method Description
Describes how the test is performed and provides a method-specific reference
A buffered enzyme incubation with substrate and cofactors is performed on lysed red blood cells. A post-incubation extraction is performed and subjected to liquid chromatography-tandem mass spectrometry. The ratio of the extracted product to its internal standard is used to calculate the total enzymatic product. This is then normalized using the calculated hemoglobin concentration to determine the patient's enzyme level in nmol/h/mg of hemoglobin.(Unpublished Mayo method)
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.
Friday
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.
82542
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 |
|---|---|---|
| GALE | UDP-galactose 4' epimerase, RBC | 79469-3 |
| 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.
|
|---|---|---|
| 64372 | UDP-galactose 4' epimerase, RBC | 79469-3 |
| 37979 | Interpretation (GALE) | 59462-2 |
| 37978 | Reviewed By | 18771-6 |