Identification of the metabolic defect in sialuria.
Sialuria is a rare inborn error of metabolism, the hallmarks of which are moderate developmental retardation, coarse facial features, and an enormous amount of free N-acetylneuraminic acid (sialic acid) in the urine. Until now, the basic biochemical defect in this disorder has remained uncertain. In this report, the activity of the rate-limiting enzyme in the biosynthesis of sialic acid has been measured directly in whole cell lysates by a highly sensitive assay. With this technique, the basic defect in sialuria has been identified unequivocally as the loss of feedback control of uridine diphosphate N-acetylglucosamine 2-epimerase by cytidine monophosphate N-acetylneuraminic acid with resultant overproduction of sialic acid.
Weiss
P
P
National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Maryland 20892.
Tietze
F
F
Gahl
W A
WA
Seppala
R
R
Ashwell
G
G
D002238:Carbohydrate Epimerases / Q000378:metabolism; D002239:Carbohydrate Metabolism, Inborn Errors / Q000378:metabolism*; D002352:Carrier Proteins; D002478:Cells, Cultured; D005246:Feedback; D005347:Fibroblasts / Q000378:metabolism; D006595:Hexosamines; D006801:Humans; D007700:Kinetics; D019158:N-Acetylneuraminic Acid; D012016:Reference Values; D012794:Sialic Acids / Q000652:urine*; D012867:Skin / Q000378:metabolism
D002352:Carrier Proteins; D006595:Hexosamines; D012794:Sialic Acids; D002238:Carbohydrate Epimerases; C024519:N-acyl-D-glucosamine 2-epimerase; C498259:RENBP protein, human; D019158:N-Acetylneuraminic Acid; C002022:N-acetylmannosamine