Octanoic acidemia and octanoylcarnitine excretion with dicarboxylic aciduria due to defective oxidation of medium-chain fatty acids.
Five patients aged 7 to 21 months are described who developed attacks of coma after a short prodromal illness with diarrhea or vomiting or both. Four had concomitant hypoglycemia, and all had hypoketonemia, with excessive urinary excretion of medium-chain dicarboxylic acids, medium-chain (omega-1)-hydroxyacids, suberylglycine, hexanoylglycine, and octanoylcarnitine. All patients accumulated octanoic acid, decanoic acid, and cis-4-decenoic acid in plasma. Fibroblasts from three patients showed a decreased rate of octanoate oxidation (10%, 12%, and 29% of control values, respectively). These findings suggest a deficiency of medium-chain acyl-CoA dehydrogenase, most probably an autosomal recessive inherited metabolic disorder. Two of the patients died during an acute attack, and a third had severe neurologic sequelae; the two remaining patients recovered. Plasma free carnitine levels were low, but total carnitine was normal. The three surviving patients underwent a fasting test, which did not lead to hypoglycemia, although hypoketonemia, dicarboxylic aciduria, and excessive mobilization of fatty acids did occur. The surviving patients were maintained on frequent carbohydrate-enriched meals.
D044944:Acyl-CoA Dehydrogenases / Q000172:deficiency*; D002210:Caprylates / Q000097:blood*; D002331:Carnitine / Q000031:analogs & derivatives* / Q000652:urine; D002478:Cells, Cultured; D003652:Decanoic Acids / Q000097:blood; D003998:Dicarboxylic Acids / Q000652:urine*; D005227:Fatty Acids / Q000172:deficiency*; D005230:Fatty Acids, Nonesterified / Q000097:blood; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D007223:Infant; D008052:Lipid Metabolism, Inborn Errors / Q000378:metabolism; D008297:Male; D010084:Oxidation-Reduction
D002210:Caprylates; D003652:Decanoic Acids; D003998:Dicarboxylic Acids; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; C031071:decanoic acid; D044944:Acyl-CoA Dehydrogenases; C008698:octanoylcarnitine; D002331:Carnitine