Long-chain Fatty Acid Oxidation Disorders (LC-FAOD)

What is Long-chain Fatty Acid Oxidation Disorders (LC-FAOD)?

Long-Chain Fatty Acid Oxidation Disorders (LC-FAOD) is a group of inherited metabolic disorders caused by defects in the enzymes responsible for the breakdown of fatty acids. As a result, the body is unable to properly break down long-chain fatty acids and uses other sources such as glucose for energy. LC-FAOD can lead to hyperammonemia (the buildup of ammonia in the blood) which can cause neurological problems such as seizures, muscular weakness and intellectual disability in children.

Types of LC-FAOD

There are seven types of LC-FAOD, each caused by a different enzyme defect:

  • Carnitine palmitoyltransferase-I (CPT-I) deficiency
  • Carnitine palmitoyltransferase-II (CPT-II) deficiency
  • Medium chain acyl-CoA dehydrogenase (MCAD) deficiency
  • Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency
  • Long-chain hydroxyacyl-CoA dehydrogenase (LCHAD) deficiency
  • Trifunctional protein deficiency
  • Beta-oxygenase deficiency

Symptoms of LC-FAOD

The symptoms of LC-FAOD vary depending on the type of disorder, but may include high levels of ammonia in the blood, low blood sugar, fatigue, poor appetite, abnormal muscle tone, intellectual disability and seizures. In more severe cases, LC-FAOD can lead to death.

Diagnosis of LC-FAOD

Diagnosis of LC-FAOD usually involves a blood test to measure levels of fatty acid levels in the body, a urine test to measure levels of ammonia and ketones, a muscle biopsy to identify the affected gene and an EEG to monitor any seizures. Genetic testing may also be done to identify the affected gene.

Treatments for LC-FAOD

Treatment for LC-FAOD may include dietary changes to reduce the amount of long-chain fatty acids a person consumes, supplementation with carnitine or other fat-soluble vitamins, and medications to control seizures. In some cases, a liver transplant may be necessary to prevent further damage to the liver.