Three siblings suffered from an unusual disorder of cyclic vomiting and congenital hepatic fibrosis. Serum transferrin isoelectric focusing showed increased asialo- and disialotransferrin isoforms as seen in the carbohydrate-deficient glycoprotein (CDG) syndrome type I. Phosphomannomutase, which is deficient in most patients with type I CDG syndrome, was found to be normal in all three patients. Structural analysis of serum transferrin revealed nonglycosylated, hypoglycosylated, and normoglycosylated transferrin molecules. These findings suggested a defect in the early glycosylation pathway. Phosphomannose isomerase was found to be deficient and the defect was present in leucocytes, fibroblasts, and liver tissue. Phosphomannose isomerase deficiency appears to be a novel glycosylation disorder, which is biochemically indistinguishable from CDG syndrome type I. However, the clinical presentation is entirely different.

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doi.org/10.1006/bbrc.1998.8385, hdl.handle.net/1765/70307
Biochemical and Biophysical Research Communications
Department of Clinical Genetics

de Koning, T., Dorland, L., van Diggelen, O., Boonman, A. M., de Jong, J., van Noort, W., … Poll-The, B. T. (1998). A novel disorder of N-glycosylation due to phosphomannose isomerase deficiency. Biochemical and Biophysical Research Communications, 245(1), 38–42. doi:10.1006/bbrc.1998.8385