title: Diagnosis of inherited disorders of galactose metabolism.
abstract: Galactose metabolism occurs through an evolutionarily conserved pathway in which galactose and uridine diphosphoglucose are converted to glucose-1-phosphate and uridine diphosphogalactose through the action of three sequential enzymes: galactokinase (GALK, EC 2.7.1.6), galactose-1-phosphate uridyltransferase (GALT, EC 2.7.7.12), and uridine phosphogalactose 4'-epimerase (GALE, EC 5.1.3.2). Inborn errors of galactose metabolism occur with impaired activity for each of the enzymes. Classical galactosemia is the most common and the most severe of these diseases and is caused by deficiency of the GALT enzyme, affecting from approximately 1 in 10,000 to 1 in 30,000 live births. Deficiency of GALE is the rarest of the three diseases. Assays for galactitol and galactose-1-phosphate and methods for assaying enzyme activities of GALT, GALK, and GALE are provided here. Interpretation of diagnostic results for screen-positive newborns or symptomatic patients, as well as therapeutic interventions based on biochemical phenotype and molecular genotype, are also included as decision trees.
authors.affiliation: Leonard Miller School of Medicine, University of Miami, Miami, Florida, USA.
authors.forename: Carla
authors.initials: C
authors.lastname: Cuthbert
authors.forename: Helene
authors.initials: H
authors.lastname: Klapper
authors.forename: Louis
authors.initials: L
authors.lastname: Elsas
mesh_terms: D002239:Carbohydrate Metabolism, Inborn Errors / Q000175:diagnosis* / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D017931:DNA Primers; D004376:Galactitol / Q000032:analysis; D005686:Galactokinase / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D005690:Galactose / Q000378:metabolism*; D005693:Galactosemias / Q000175:diagnosis / Q000235:genetics / Q000378:metabolism; D005695:Galactosephosphates / Q000032:analysis; D005826:Genetics, Medical; D006801:Humans; D007231:Infant, Newborn; D015997:Neonatal Screening; D016133:Polymerase Chain Reaction; D014534:UDPglucose 4-Epimerase / Q000032:analysis / Q000172:deficiency / Q000235:genetics; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase / Q000032:analysis / Q000172:deficiency / Q000235:genetics
chemical_list: D017931:DNA Primers; D005695:Galactosephosphates; D004376:Galactitol; C029973:galactose-1-phosphate; D005686:Galactokinase; D005694:UTP-Hexose-1-Phosphate Uridylyltransferase; D014534:UDPglucose 4-Epimerase; D005690:Galactose