Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:5.4.2.8 (phosphomannomutase)
 238 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Isoelectrofocusing of serum sialotransferrins from patients with untreated hereditary fructose intolerance (HFI) shows a cathodal shift similar to that in carbohydrate-deficient glycoprotein (CDG) syndrome type I and in untreated galactosemia. This report is on serum lysosomal enzyme abnormalities in untreated HFI that are identical to those found in CDG syndrome type I but different from those in untreated galactosemia. CDG syndrome type I is due to phosphomannomutase deficiency, a defect in the early glycosylation pathway. It was found that fructose 1-phosphate is a potent competitive inhibitor (Ki congruent to 40 microM) of phosphomannose isomerase (EC 5.3.1.8), the first enzyme of the N-glycosylation pathway thus explaining the N-glycosylation disturbances in HFI.
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PMID:Inhibition of phosphomannose isomerase by fructose 1-phosphate: an explanation for defective N-glycosylation in hereditary fructose intolerance. 891 Sep 43

Female classic galactosemia patients suffer from primary ovarian insufficiency (POI). The cause for this long-term complication is not fully understood. One of the proposed mechanisms is that hypoglycosylation of complex molecules, a known secondary phenomenon of galactosemia, leads to FSH dysfunction. An earlier study showed less acidic isoforms of FSH in serum samples of two classic galactosemia patients compared to controls, indicating hypoglycosylation. In this study, FSH isoform patterns of five classic galactosemia patients with POI were compared to the pattern obtained in two patients with a primary glycosylation disorder (phosphomannomutase-2-deficient congenital disorders of glycosylation, PMM2-CDG) and POI, and in five postmenopausal women as controls. We used FPLC chromatofocussing with measurement of FSH concentration per fraction, and discovered that there were no significant differences between galactosemia patients, PMM2-CDG patients and postmenopausal controls. Our results do not support that FSH dysfunction due to a less acidic isoform pattern because of hypoglycosylation is a key mechanism of POI in this disease.
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PMID:FSH isoform pattern in classic galactosemia. 2081 26

Congenital Disorders of Glycosylation (CDG) are a group of recently described inborn errors of metabolism affecting glycosylation. CDG are disorders that have been reported with a great variability in the clinical presentation, especially for the most common PMM2-CDG. The classical form is neurologic but severe forms with multisystem disorders and hydrops fetalis have been described. Here, we extend on the opposite end the clinical spectrum to an asymptomatic PMM2-CDG case. The case was the father of a child who died of neonatal galactosemia few days after birth. He presented without any clinical or biological signs, except a typical CDG 1 pattern in Western blot of glycoproteins associated with a deficient phosphomannomutase activity in blood leukocytes and compound heterozygosity in PMM2 gene. The sister of the father, who was also affected by PMM deficiency, presented with infertility and premature ovarian failure. Finally, the absence of any abnormal clinical or biological signs as for the case completes the clinical spectrum of PMM2-CDG at its extreme end, at the opposite of the supposed total lethality of the R141H homozygous status.
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PMID:Expanding the Spectrum of PMM2-CDG Phenotype. 2343 Sep 27