Long-chain fatty acid oxidative disorders (LC-FAOD) are a type of rare and potentially life-threatening genetic metabolic disorders that affect the body’s ability to use fats from food as a source for energy.

The body has many enzymes and transporters involved in converting fat to energy and genetic defects in almost all these enzymes have been found in patients with fatty acid oxidative disorders. Fatty acids are metabolized in the mitochondria where specific enzymes break down each of the fatty acids to produce adenosine triphosphate (ATP) for energy. Mutations in the genes encoding the enzymes that break down long-chain fatty acids may lead to severe energy deficits.

The symptoms and severity of LC-FAOD can vary; the most severe cases are diagnosed within the first few days or weeks of life. Patients with LC-FAOD often suffer from severe energy deficit that results in extreme fatigue. They may have liver dysfunction, hypoglycemia, encephalopathy, and high risk for sudden death. Older patients usually have milder forms of the disease and may experience lack of endurance, poor exercise tolerance, muscle aches, rhabdomyolysis or breakdown of muscle tissue, and are at risk of developing kidney injury.

Current management of LC-FAOD is limited to lifestyle changes such as changes in the diet and avoidance of prolonged fasting. Many patients with LC-FAOD take specific dietary and nutritional supplements such as medium chain triglycerides (MCT).