Sign in →

Test ID: GALK Galactokinase, Blood

Reporting Name

Galactokinase, B

Useful For

Diagnosis of galactokinase deficiency, the second most common cause of galactosemia

Testing Algorithm

See Galactosemia Testing Algorithm in Special Instructions.

Specimen Type

Whole Blood EDTA


Advisory Information


This test is for diagnosis of galactokinase (GALK) deficiency. The most common cause of galactosemia is GALT deficiency. In most cases, GALT deficiency should be ruled out prior to evaluating for galactokinase (GALK) deficiency (see GCT / Galactosemia Reflex, Blood).

 

To evaluate for galactose-1-phosphate uridyltransferase deficiency, see GALT / Galactose-1-Phosphate Uridyltransferase, Blood.

 

This assay will not detect UDP-galactose 4' epimerase (GALE) deficiency or galactose-1-phosphate uridyltransferase (GALT) deficiency. For epimerase deficiency, see GALE / UDP-Galactose 4' Epimerase (GALE), Blood.

 

This assay is not appropriate for monitoring dietary compliance; see GAL1P / Galactose-1-Phosphate (Gal-1-P), Erythrocytes.



Specimen Required


Container/Tube:

Preferred: Lavender top (EDTA)

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

Specimen Volume: 4 mL


Specimen Minimum Volume

2 mL

Specimen Stability Information

Specimen Type Temperature Time
Whole Blood EDTA Refrigerated (preferred) 10 days
  Ambient  72 hours

Reference Values

≥0.7 nmol/h/mg of hemoglobin

Day(s) and Time(s) Performed

Mondays; 9 a.m.

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 U.S. Food and Drug Administration.

CPT Code Information

82759

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GALK Galactokinase, B 81143-0

 

Result ID Test Result Name Result LOINC Value
38005 Galactokinase, B In Process
38007 Interpretation (GALK) In Process
38006 Reviewed By No LOINC Needed

Clinical Information

Galactokinase (GALK) deficiency is the second most common form of galactosemia, affecting approximately 1 in 250,000 live births, with a higher frequency in the Romani population. Individuals with GALK deficiency have a milder clinical presentation than that seen in patients with classic galactosemia, galactose-1-phosphate uridyltransferase (GALT) deficiency. The major clinical manifestation is bilateral juvenile cataracts.

 

GALK deficiency is treated with a lactose-restricted diet. Early treatment may prevent or reverse the formation of cataracts.

 

In GALK deficiency, erythrocyte galactose-1-phosphate levels are generally normal and plasma galactose levels are generally elevated. The diagnosis is established by demonstrating deficient GALK enzyme activity in erythrocytes. Testing for GALK deficiency should be performed when there is a suspicion of galactosemia, either based upon the patient's clinical presentation or laboratory studies and GALT deficiency has been excluded. Specimens sent for GALT analysis may be used for GALK testing if the original specimen was received in the laboratory within the stability parameters listed in Specimen Stability Information.

 

GALK deficiency is caused by mutations in the GALK1 gene. Gene analysis is available from some commercial laboratories. Contact Mayo Medical Laboratories for recommendations or contact information for laboratories that offer this testing.

 

See Galactosemia Testing Algorithm in Special Instructions.

Interpretation

An interpretive report will be provided.

 

See Galactosemia Testing Algorithm in Special Instructions for additional information.

Clinical Reference

1. Li, Y, Ptolemy AS, Harmonay L, et al: Ultra fast and sensitive liquid chromatography tandem mass spectrometry based assay for galactose-1-phosphate uridylyltransferase and galactokinase deficiencies. Mol Gen Metab 2011;102(1):33-40

2. Ko DH, Jun SH, Park HD, et al: Multiplex enzyme assay for galactosemia using ultraperformance liquid chromatography-tandem mass spectrometry. Clin Chem 2010;56:764-771

3. Hennermann JB, Schadewaldt P, Vetter B, et al: Features and outcome of galactokinase deficiency in children diagnosed by newborn screening. J Inherit Metab Dis 2011;34:399-407

4. Walter JH, Fridovich-Keil JL: Galactosemia. In The Online Metabolic and Molecular Bases of Inherited Disease. Edited by D Valle, AL Beaudet, B Vogelstein, et al. McGraw-Hill, New York, 2014, Accessed March 31, 2017. Available at: http://ommbid.mhmedical.com/content.aspx?bookid=971&Sectionid=62672411

Analytic Time

8 days

Method Name

Enzyme Reaction Followed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Forms

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 (T576) is available in Special Instructions

2. Biochemical Genetics Patient Information (T602) in Special Instructions.

Mayo Medical Laboratories | Genetics and Pharmacogenomics Catalog Additional Information:

mml-biochemical