Transferrin and apolipoprotein C-III isofocusing are complementary in the diagnosis of N- and O-glycan biosynthesis defects.

Abstract

BACKGROUND:

Apolipoprotein C-III (apoC-III) isoelectric focusing (IEF) can be used to detect abnormalities in the biosynthesis of core 1 mucin-type O-glycans.

METHODS:

We studied plasma samples from 55 patients with various primary defects in N- and/or O-glycosylation, 21 patients with secondary N-glycosylation defects, and 6 patients with possible glycosylation abnormalities. Furthermore, we analyzed 500 plasma samples that were sent to our laboratory for selective screening for inborn errors of metabolism.

RESULTS:

Plasma samples from patients with congenital disorders of glycosylation (CDG) types -IIe and -IIf showed a hypoglycosylated apoC-III isoform profile, as did plasma samples from 75% of the patients with an unspecified CDG type II. Hyposialylated O-glycan profiles were also seen in plasma from 2 patients with hemolytic-uremic syndrome. In the 500 plasma samples from the selective screening, 3 patients were identified with a possible isolated defect in the biosynthesis of core 1 mucin-type O-glycans.

CONCLUSIONS:

To our knowledge this is the first study in which use of a plasma marker protein has identified patients in whom only O-glycan biosynthesis might be affected. The primary defect(s) remain as yet unknown. Plasma apoC-III IEF is complementary to transferrin isofocusing. In conjunction both tests identify biosynthesis defects in N-glycan and mucin-type core 1 O-glycan biosynthesis. The apoC-III IEF assay is likely to help metabolic laboratories to identify and unravel further subtypes of inborn errors of glycan biosynthesis.

• Authors: Suzan Wopereis, Stephanie Grünewald, Karin M L C Huijben, Eva Morava, Rosella Mollicone, Baziel G M van Engelen, Dirk J Lefeber, Ron A Wevers
• Journal: Clinical chemistry (Clin Chem) Vol. 53 Issue 2 Pg. 180-7 (Feb 2007) ISSN: 0009-9147 [Print] England
• PMID: 17170056 (Publication Type: Case Reports, Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Apolipoprotein C-III
• Polysaccharides
• Protein Isoforms
• Transferrin

Topics

• Adolescent
• Apolipoprotein C-III (blood)
• Child
• Child, Preschool
• Female
• Glycosylation
• Humans
• Infant
• Infant, Newborn
• Infant, Premature
• Isoelectric Focusing
• Male
• Metabolism, Inborn Errors (blood, genetics)
• Polysaccharides (biosynthesis)
• Protein Isoforms (blood)
• Retrospective Studies
• Transferrin (metabolism)