NEW VARIANT OF GALACTOSEMIA

Abstract

Several variants of galactose-1-phosphate uridyltransferase (G-l-P UT) are known. We have studied an infant with what is probably a new biochemical variant of galactosemia. He was identified by routine newborn screening at the age of 3 days when he was found to have a slightly increased blood galactose concentration. Unlike “classical” galactosemics, blood galactose in this infant varied from 50 mg/100 ml. on a normal diet. Activity of erythrocyte G-1-P UT was measured at 0.6 U/gm Hgb by UDPG consumption assay at 3 hour incubation. This is within the range of activity found in “classical” galactosemia and is less than corresponding activity in any “Duarte” variant state. However, in contrast to “classical” galactosemia and the “Negro” variant, there was repeatedly moderate activity by the fluorescent spot technique after 16 hours incubation. Additional studies ruled out presence of the “Indiana” variant. By a “milk loading test”, this infant accumulated galactose in blood to a peak of >50 mg/100 ml. at 90 minutes but completely cleared galactose from the blood by 180 minutes, in contrast to a “classical” patient who did not clear by 4 hours, to a “Negro” variant patient who “peaked” only to 4 mg/100 ml., and to “Duarte” variant patients who did not accumulate any detectable blood galactose. Galactosemic variants such as this have considerable significance in terms of therapy and subsequent evaluation.