Rapid method for screening for galactosemia and galactokinase deficiency by measuring galactose in whole blood spotted on paper.

Two major metabolic disorders are associated with galactose metabolism: galactokinase (ATP : D-galactose1-phosphotransferase, EC 2.7.1.6) deficiency and galactosemia (1) secondary to a deficiency in galactose-i-phosphate uridyl transferase (UTP: a-D-galactose-i-phosphate uridyltransferase, EC 2.7.7.10) activity. One case reported in 1972 (2) described a third enzymatic (UDPglucose 4-epimerase, EC 5.1.3.2) deficiency related to galactose metabolism. The clinical manifestations in galactosemia may vary in severity from perinatal death to mental retardation, cataracts, and hepatic cirrhosis; cataracts may be the only symptom of galactokinase deficiency. The infant reported (2) with the epimerase deficiency was apparently healthy. Abnormally high concentration of galactose in the blood of milk-fed newborns is a biochemical manifestation of these disorders. We propose a modified technique (3) adapted to dried blood spots, which is rapid and sensitive. Another automated method for blood galactose determination has already been proposed (4). It requires blood spots of 14-mm diameter, much bigger than those usually collected for phenylketonuria screening (5, 6). The Guthrie test based on bacterial inhibition (7) also measures blood galactose and remains an alternative procedure to the one presented in this paper. Other techniques for the screening for galactosemia depend on measurements of uridyltransferase activity by use of dried blood on paper