The role of methionine in ethylmalonic encephalopathy with petechiae.

Among patients with ethylmalonic aciduria, a subgroup with encephalopathy, petechial skin lesions, and often death in infancy is distinct from those with short-chain acyl-coenzyme A dehydrogenase deficiency or multiple acyl-coenzyme A dehydrogenase deficiency. The nature of the molecular defect in this subgroup is unknown, and the source of the ethylmalonic acid has been unclear. To determine whether the administration of candidate amino acids increased the excretion of ethylmalonic acid. Examination of patterns of organic acids excreted in the urine before and following loading doses of isoleucine and methionine. General clinical research center. An infant with ethylmalonic aciduria, global developmental delay, acrocyanosis, and intermittent showers of petechiae. Excretion of ethylmalonic acid in the urine. Loading with methionine increased the excretion of ethylmalonic acid, whereas loading with isoleucine did not. Restriction of the dietary intake of methionine decreased ethylmalonic acid excretion. In ethylmalonic acid encephalopathy with petechiae, methionine is a precursor of ethylmalonic acid.