Fatty acids are one of the body's fuels: oxidation is the process by which they are broken down to release energy. This process has many steps, each catalysed by a different enzyme. Fatty acid oxidation disorders result from deficiency of one of these enzymes:

• Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency
• Very-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency
• Short-chain acyl-CoA dehydrogenase (SCAD) deficiency
• Multiple acyl-CoA dehydrogenase (MAD) deficiency (= Glutaric aciduria type II, GA II)
• Long-chain hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency
• Trifunctional protein deficiency
• Carnitine palmitoyl-transferase I (CPT I) deficiency
• Carnitine palmitoyl-transferase II (CPT II) deficiency
• Carnitine acylcarnitine translocase deficiency
• Primary (systemic) carnitine deficiency

MCAD deficiency is the commonest disorder. Patients with MCAD deficiency are healthy most of the time. Infections or prolonged fasting, however, can lead to drowsiness and coma or sudden death. This can be prevented by avoiding fasting and maintaining a regular intake of sugar during infections - by mouth or intravenously if the child vomits. With this simple management, outcomes are excellent.

Patients with other fatty acid oxidation disorders also need to avoid fasting and to maintain a regular sugar intake during infections. Unfortunately, they can have additional problems, such as muscle problems or heart muscle disease. Treatment usually involves a low fat diet.

Inheritance patterns
All these disorders show autosomal recessive inheritance.

Prenatal diagnosis
Prenatal diagnosis is available for these disorders.

Medical text written October 2000 by Dr A Morris. Last reviewed August 2005 by Dr A Morris, Consultant Paediatrician with Special Interest in Metabolic disease, Willink Biochemical Genetics Unit, Royal Manchester Children's Hospital, Manchester, UK.

While there is no specific support group in the UK for Fatty Acid Oxidation Disorders, support and information is available from a group of families under the umbrella of Climb (see entry, Metabolic diseases). The US FOD Family Support Group http://www.fodsupport.org acts as an international group.