There are still many problems with the diagnosis and classification of inherited disorders of mitochondrial beta-oxidation. At present only the
acyl-CoA dehydrogenase step of the beta-oxidation spiral has been explored in any detail and a large number of patients have disorders that cannot be properly characterized. beta-Oxidation defects may present in a wide variety of ways, the most dramatic being acute
encephalopathy with hepatic involvement (atypical
Reye's syndrome) or '
sudden' death. Investigations may include urinary and plasma organic
acids, metabolic stress tests and assays of overall metabolic pathways or of specific
enzymes in cultured fibroblasts, lymphocytes, or other material. Early postnatal diagnosis presents particular difficulties but in
medium-chain acyl-CoA dehydrogenase deficiency the diagnosis may be apparent from careful examination of urine. There is as yet little general experience in prenatal diagnosis of this group of disorders except for
glutaric aciduria type II. Single prenatal diagnoses of
medium-chain acyl-CoA dehydrogenase deficiency and of an incompletely characterized defect of medium-chain
fatty acid oxidation have been performed.