Vitamin B12 responsive homocystinuria and megaloblastic anemia: heterogeneity in methylcobalamin deficiency.

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Rosenblatt DS, Thomas IT, Watkins D, Cooper BA, Erbe RW

Vitamin B12 responsive homocystinuria and megaloblastic anemia: heterogeneity in methylcobalamin deficiency.

Am J Med Genet. 1987 Feb;26(2):377-83.

PubMed ID

3812589 [ View in PubMed

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Abstract

A male infant with methyl-B12 deficiency (cblE) presented at age 6 weeks with lethargy, staring spells, and vomiting. He later became hypotonic and unresponsive to stimuli and required intubation and ventilation. He had homocystinuria and hypomethioninemia with megaloblastic anemia but normal serum folate and vitamin B12 concentrations. No methylmalonic aciduria was detected. Fibroblasts, cultured from the patient, were unable to grow in medium in which homocysteine replaced methionine and incorporated abnormally small amounts of [14C]-methyl-tetrahydrofolate but normal amounts of [14C]-propionate into protein. Methyl-B12 content of fibroblasts was low, while the adenosyl-B12 content was normal. Methionine synthase activity was decreased when the assay was performed under both optimal and suboptimal reducing conditions, suggesting heterogeneity in the cblE disease. The patient responded dramatically to hydroxocobalamin treatment. Homocystinuria disappeared after 10 days of therapy, and methionine was normalized after 3 weeks. Psychometric testing at age 15 months showed a developmental age of 9 months.

DrugBank Data that Cites this Article

Drug Targets

Drug	Target	Kind	Organism	Pharmacological Action	Actions
Hydroxocobalamin	Methionine synthase	Protein	Humans	Yes	Cofactor	Details