Episodes of severe metabolic acidosis in a patient with 3-methylglutaconic aciduria.

Persistent excretion of 3-methylglutaconic acid was found in a 6-month-old infant with multiple minor physical malformations and delayed development. During two episodes of intercurrent viral illness, the patient developed severe metabolic acidosis and excreted large amounts of lactate, 3-hydroxybutyrate and acetoacetate. The excretion of 3-methylglutaconic acid did not change during these episodes, nor did it increase following leucine loading. In vitro studies suggest that in this patient, as in the majority of other patients with 3-methylglutaconic aciduria, a primary defect in leucine metabolism is not responsible for the biochemical abnormality.