A variant form of 2-methyl-3-hydroxybutyric and 2-methylacetoacetic aciduria.

A new case of assumed beta-ketothiolase deficiency, excreting 2-methyl-3-hydroxybutyrate and tiglylglycine is described in a 15-year-old boy. The patient presented with episodes of metabolic acidosis following intercurrent infections in the early childhood. After the age of 7 years he has had periods of headache, but no acidotic episodes have occurred even during infections. Systematic dietary treatment has not been instituted, and the patient is physically and mentally normal. This indicates a mild variant of the beta-ketothiolase deficiency. Diagnosis of the condition may be obscured by large quantities of ordinary ketone bodies, and requires gas chromatographic and mass spectrometric techniques.