Clinical and biochemical aspects of carnitine deficiency and insufficiency: transport defects and inborn errors of beta-oxidation.

Carnitine is required for entry of long chain fatty acids into mitochondria where beta-oxidation occurs. Primary carnitine deficiency, due to a generic defect in cellular carnitine transport, exists in myopathic and systemic forms. Secondary carnitine deficiency may be due to multiplicity of inherited abnormalities, including deficiencies in carnitine palmitoyl-transferase acyl-CoA dehydrogenases, electron transfer flavoprotein, and 3-ketoacyl-CoA-thiolase. The clinical features, diagnosis, and treatment of these conditions are described.