3-HYDROXYDICARBOXYLIC AND 3-KETODICARBOXYLIC ACIDURIA IN 3 PATIENTS -EVIDENCE FOR A NEW DEFECT IN FATTY-ACID OXIDATION AT THE LEVEL OF 3-KETOACYL-COA THIOLASE

Three patients presented with evidence of a fatty acid oxidation disor der. Analysis of urinary organic acids by gas chromatography/mass spec trometry demonstrated the presence of medium-chain (C6-C-12) dicarboxy lic, 3-hydroxydicarboxylic, and 3-ketodicarboxylic acids in all three urines. 3-Ketodicarboxylic aciduria is reported for the first time her e, as are the mass spectra for 3-ketosuberic, 3-ketosebacic, and 3-ket ododecanedioic acids and the oximated spectrum for 3-ketoadipic acid. The presence of 3-ketodicarboxylic acids suggests a defect at the leve l of a long-chain 3-ketoacyl-CoA thiolase, an enzyme for which a defic iency state has not previously been described. Our patients may repres ent the first cases of a long-chain thiolase defect.