Phosphomannomutase deficiency is a cause of carbohydrate-deficient glycoprotein syndrome type I.
Carbohydrate-deficient glycoprotein (CDG) syndromes are genetic multisystemic disorders characterized by defective N-glycosylation of serum and cellular proteins. The activity of phosphomannomutase was markedly deficient (< or = 10% of the control activity) in fibroblasts, liver and/or leucocytes of 6 patients with CDG syndrome type I. Other enzymes involved in the conversion of glucose to mannose 1-phosphate, as well as phosphoglucomutase, had normal activities. Phosphomannomutase activity was normal in fibroblasts of 2 patients with CDG syndrome type II. Since this enzyme provides the mannose 1-phosphate required for the initial steps of protein glycosylation, it is concluded that phosphomannomutase deficiency, which is first reported here for higher organisms, is a cause, and most likely the major one, of CDG syndrome type I.
Van Schaftingen
E
E
Laboratory of Physiological Chemistry, ICP, Louvain, Belgium.
Jaeken
J
J
D000328:Adult; D002675:Child, Preschool; D018981:Congenital Disorders of Glycosylation / Q000145:classification / Q000201:enzymology / Q000209:etiology*; D005260:Female; D005947:Glucose / Q000378:metabolism; D006031:Glycosylation; D006801:Humans; D007223:Infant; D008099:Liver / Q000201:enzymology; D008359:Mannose-6-Phosphate Isomerase / Q000032:analysis; D008360:Mannosephosphates / Q000096:biosynthesis; D010733:Phosphoglucomutase / Q000032:analysis; D017875:Phosphotransferases (Phosphomutases) / Q000032:analysis / Q000172:deficiency*; D011499:Protein Processing, Post-Translational
D008360:Mannosephosphates; C047217:mannose 1-phosphate; D008359:Mannose-6-Phosphate Isomerase; D017875:Phosphotransferases (Phosphomutases); D010733:Phosphoglucomutase; C052799:phosphomannomutase; D005947:Glucose