Galactosaemia Screen (Dried Blood Spot)

Diagnostic Use

Newborn baby screening measures galactose + galactose-1-phosphate and detects the classical transferase, epimerase and kinase deficiencies.

The preferred galactosaemia screen for symptomatic patients is the measurement of galactose, galactose-1-phosphate and galactose-1-phosphate uridyltransferase enzyme. Urine reducing substances, even non-glucose reducing substances, are an unreliable screen.

Patients with galactosaemia often present in the second week of life with liver dysfunction, vomiting and possibly sepsis. They may have early evidence of cataracts. Late infantile presentation with failure to thrive, cataracts, hepatic disease and/or rickets is well described.  In New Zealand newborns are screened for classical galactosemia. These patients have very low transferase activities. There are a number of ‘non-disease’ alleles, the Duarte variant being the most well known, which can lead to decreased activity (10-20%) but are usually, if not always, benign. Most patients with classical galactosemia are homozygous for a common mutation (Q188R).

Patients with cataracts may have the very rare conditions galactokinase and UPDGal epimerase deficiency. The latter may also present like galactosemia.  Red cell galactose-1-phosphate and plasma galactose are helpful in diagnosing these conditions.

Red cell galacatose-1-phosphate is useful in monitoring dietary compliance in classical galactosemia.

Reference Intervals

The reference interval will be provided with the result.