Galactosemia is an autosomal recessive disorder of galactose metabolism that often presents in the newborn period with poor suck, vomiting, diarrhea, bleeding diathesis, lethargy, jaundice, and sepsis. If left untreated, an individual may progress to irreversible liver disease and mental retardation.
Galactokinase deficiency should be considered in individuals with cataracts, elevated red cell galactose, galactosuria, or elevated urinary galactitol and normal GALT enzyme activity. Galactokinase converts galactose to galactose-1-phosphate. The deficiency results in the accumulation of galactose and urine galactitol.
Galactokinase activity is used to rule-out variant galactosemia due to galactokinase deficiency. Galactokinase deficiency should not be confused with classical Galactosemia secondary to GALT deficiency. Refer to Galactosemia: Comprehensive Panel (GS) for a disease overview.
Click here for the GeneReviews summary on this condition.
This test is indicated in the case of:
- Normal galactose-1-phosphate and normal GALT activity
- Galactosemia with cataracts
Galactokinase is evaluated by measuring the enzyme's ability to convert galactose to galactose-1-phosphate using a radioenzymatic reaction.
Detection and Reference Range
Detection of reduced galactokinase activity is diagnostic of galactokinase deficient galactosemia.
0-2 yrs: 0.92 - 4.4 umol/hr/gm Hb
>3 yrs: 0.62 - 1.93 umol/hr/gm Hb
Type: Whole Blood
Specimen Requirements:In sodium heparin (green top) tube: 3-5 ml
Specimen Collection and Shipping: Refrigerate until time of shipment. Ship sample overnight at room temperature for receipt at EGL within 24 hours of collection.
- Galactitol (test code GL) - biochemical screening test for diagnosis and monitoring of patients with galactosemia.
- Galctose-1-Phosphate (test code GP) - biochemical screening test for diagnosis and monitoring of patients with galactosemia.
- Galactosemia: Nonclassic Galactosemia Panel (GALK & GALE Enzymes and Galactose-1-Phosphate) (test code BGKEP).
- Galactosemia (Galactokinase Deficiency): Full Gene Sequencing (test code IQ) - if the proband has a biochemical diagnosis of galactokinase deficiency.
- Custom Diagnositic Mutation Analysis (test code KM) is available to individuals. Please contact the laboratory genetic counselor to arrange testing.
- Galactosemia (Galactokinase Deficiency): Deletion/duplication (test code JA) - when mutations are not detected by full gene sequencing.
- Prenatal testing is available by molecular methods. Please contact the laboratory genetic counselor to determine the availability of prenatal testing.