NEONATAL HEMOLYTIC-UREMIC SYNDROME, METHY LMALONIC ACIDURIA AND HOMOCYSTINURIA DUE TO A CONGENITAL DEFECT IN INTRACELLULAR COBALAMIN METABOLISM

Background. A hemolytic-uremic syndrome associated with methylmalonic aciduria and homocystinuria is seen during the first weeks of life. A molecular defect in the CbIC mutation has been found. This report desc ribes a new case with this association. Case report. A girl, the secon d in this family, was born at term: her birth weight was 2 100 g, heig ht was 47 cm and head circumference 31,5 cm. She was admitted at 32 da ys of age with hemolytic anemia and fragmencytosis, renal failure and thrombocytopenia. The renal failure required peritoneal dialysis follo wed by hemofiltration. The signs of pancytopenia of central origin and liver failure seen at that time raised the possibility of an intracel lular defect of B12 metabolism. Chromatography of the aminoacids and o rganic acids in the urine and plasma revealed homocystinemia, hypometh ioninemia, homocystinuria and methylmalonic aciduria. The deficient B1 2 metabolism was confirmed in fibroblasts which showed deficits in bot h methyl and adenosylcobalamin synthesis. The metabolic disturbances w ere completely resolved after intravenous administration of hydroxy-co balamin (2 000 mug per day) and folinic acid (25 mg per day) for 5 day s. But the neurological abnormalities persisted, with retinitis pigmen tosa and major leukodystrophic changes seen by MRI, and the infant die d one month later. Conclusion. This new case emphasizes the importance of systematically screening all cases of neonatal hemolytic-uremic sy ndrome for this autosomal recessive disorder.