A NEW APPROACHTO THE NEWBORN SCREENING FOR METABOLIC DISORDERS: USE OF FLOW-INJECTION ANALYSIS WITH IMMOBILIZED DEHYDROGENASES

Abstract

Three highly specific NADH-dependent dehydrogenases are studied for application in clinical analysis, particularly in newborn screening of three metabolic disorders: 1. Hydroxyisocaproate dehydrogenase for the selective determination of ketoisocaproate in Maple Syrup Urine Disease, 2. L-phenylalanine dehydrogenase for the determination of L-phenylalanine in hyperphenylalaninemias, and 3. galactose dehydrogenase for the detection of galactosemia. After immobilization, each of the three enzymes can be applied as enzyme reactors in a flow-injection analysis system. Calibration curves reveal that the sensitivity of the three methods enables the measurement of the three metabolites in the normal and the high range. First applications of these methods with plasma samples are given, a sample frequency of 60 - 100 samples per hour can be reached in each case.