Three Biochemical Subtypes in Type I Carbohydrate-Deficient Glycoprotein Syndrome (CDGS). • 614

Abstract

CDGS is a group of disorders with clinical and biochemical heterogeneity, presenting in infancy with developmental delay, multisystemic involvement and abnormal serum glycoproteins. Clear evidence exists that defects both in the earliest part of the N-linked oligosaccharide synthetic pathway, dolichol-linked oligosaccharide (DLO) synthesis, and more distal steps, processing the protein-linked oligosaccharide (PLO), result in the Type I phenotype. However, despite similar clinical presentation and diagnostic testing, not all Type 1 CDGS patients have the same biochemical defect. Fibroblasts from a subpopulation of Type 1 CDGS patients have been shown to have phosphomannomutase deficiency (FEBS Letters 377:318, 1995). We now report that 3 biochemical subtypes can be dissected from the Type I CDGS population using fibroblast metabolic labelling.