Analysis index

Special filter paper with 4 – 5 drops capillary blood from the heel (Extraction conditions: please refer to newborn screening) or 1 ml EDTA-blood

Gal-1-PUT > 2,0 U/gHb: negative

Gal-1-PUT 1,0 – 2,0 U/gHb: grey area, a repeat screening test (filter paper) is required immediately

Gal-1-PUT < 1,0 U/gHb: positive

A minimum of 2 ml EDTA-blood is required for the evaluation of Gal-1-PUT and genotyping as well as 0,5 ml sodium fluoride blood (glucose monovette tube with yellow cap) for glucose determination. Determination of the Gal-1-PUT activity (Galactose-1-phosphate uridyltransferase activity) in the erythrocytes. In 1:100 – 1:5000 cases, false-positive results may show. In any case, the evaluation of galactose (sodium fluoride blood) or galactose-1-phosphate (Hemolysate, see there) is required.

Molecular-genetic evaluation: Early detection of “classical galactosemia” with sequencing of all exons and introns (2 ml EDTA-blood)

Early detection of galactosemia

Gal-1-PUT-activity determination is carried out along with the newborn screening.

Three enzymes are involved in the galactose metabolization:

1. Galactose-1-phosphate-uridyltransferase activity (Gal-1-PUT) (Incidence of deficiency 1 : 30.000, classical galactosemia)
2. Galactokinase (Incidence of deficiency 1 : 50.000)
3. UDP-galactose-4-epimerase (very rare).

The reason for severe clinical presentation with icterus, vomiting, lethargy, hypoglycemia and failure to thrive is practically always a decrease in Gal-1-PUT activity.

Galactokinase deficiency leads to a progressive development of serious cataracts.

UDP-galactose-4-epimerase deficiency, which is very rare, has no or just very mild clinical symptoms.

The large majority of classical galactosemia (1) cases shows increased galactose values even without consumption of milk or other galactose-containing food products. Prerequisite for the demonstration of the two other types (2 & 3) is the consumption of a sufficient amount of milk prior to blood extraction. Blood should be taken two hours after food consumption.