Carbohydrate deficient glycoprotein syndrome (CDGS) type II. Phosphomannose isomerase (PMI) deficiency.
Incidence
Very rare. Only 3 pts reported (3 siblings).
Clinical Characteristics
Contrary to carbohydrate deficient glycoprotein syndrome (CDGS) type I (PMM deficiency), these pts with CDGS type II have no mental nor psychomotor retardation. The main clinical feature is cyclic vomiting with onset in the newborn period and congenital hepatic fibrosis, hepatomegaly, low blood albumin.There is also diarrhea leading to dehydration. Many hospital admissions. Serun transferrin isoelectric focusing shows increased asialo- and disialotransferrin isoforms as seen in CDGS type I. PMI activity is deficient in fibroblasts, leukocytes and liver tissue. PMI deficient pts have many similarities with the clinical symptoms of hereditary fructose intolerance (HFI). Untreated HFI causes defective glycosylation. Fructose-1-phosphate inhibits PMI, explaining the hypoglycosylation in fructose intolerance. Mannose is a constituent of glycoproteins. Pts can not make mannose from glucose because PMI deficiency. Treatment of PMI pts with D-mannose is effective.
Precipitants
no
Provocation Tests
no
Diagnostic Procedures
Serun transferrin isoelectric focusing shows increased asialo- and disialotransferrin isoforms as seen in CDGS type I. PMI activity is deficient in fibroblasts, leukocytes and liver tissue.