Frequently asked questions (FAQ) about FAOD

Fatty acid oxidation disorders (FAOD) are a group of ultrarare genetic conditions in which an enzyme that ordinarily breaks down fat is either at a very low level or not functioning normally. The inability to process fats effectively can lead to energy depletion and, in some patients, clinical symptoms.

Learn more about what causes FAOD.

FAOD affect 1 in 4600 people in the United States
Long-chain FAOD (LC-FAOD) are a specific group of FAOD. The most common types of LC-FAOD are

  • Very long–chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency
  • Long-chain 3-hydroxyacyl-coenzyme A dehydrogenase (LCHAD) deficiency
  • Trifunctional protein (TFP) deficiency
  • Carnitine palmitoyltransferase I and II (CPT I and II) deficiency

Learn about the different kinds of FAOD.

FAOD are inherited diseases. If two people carry a specific FAOD mutation, their children may inherit the disorder.

See how the inheritance pattern of FAOD, called autosomal recessive, works.

No. FAOD are a collection of conditions that impact people differently and symptoms can vary in severity and age of onset. The most common symptoms of FAOD are:

  • Pain (muscle pains, cramps, weakness)
  • A breakdown of muscle fibers (rhabdomyolysis)
  • Low blood sugar (hypoglycemia)
  • Decreased muscle tone and weakness (hypotonia)
  • Heart muscle weakness (cardiomyopathy)

Learn more about the signs and symptoms of FAOD.

Starting in 1999, newborn screening gradually expanded by state to include testing for FAOD. For people born before 1999, they can be evaluated for suspected FAOD symptoms and may need to take a blood test.
Talk to your doctor if you suspect that you may have FAOD.

Learn more about FAOD diagnosis.

Talk to your doctor if you suspect that you or your child may have FAOD. Your doctor can help you find a specialty metabolic or genetics clinic for testing.
Currently, there are no FDA-approved treatments for FAOD. Supportive care options to maintain energy levels in LC-FAOD may include taking dietary supplements, such as medium-chain triglyceride (MCT) oil and/or taking prescribed carnitine, avoidance of fasting, and monitoring carbohydrate and fat intake. If you suspect you have FAOD, talk to your doctor about supportive care options that are appropriate for you.

Learn about managing FAOD.

If you are interested in clinical study opportunities for FAOD, talk to your doctor or sign up to learn more.

For additional information on clinical studies for FAOD, visit

Learn about clinical studies in FAOD.

Support groups can make a difference in the lives of people with FAOD.

Visit the Advocacy & resources section of this website to learn more.

Learn how FAOD are Managed

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References: 1. Fatty acid oxidation disorders. The Screening, Technology and Research in Genetics (STAR-G) Project. Updated February 20, 2016. Accessed August 17, 2016. 2. Lindner M, Hoffmann GF, Matern D. Newborn screening for disorders of fatty-acid oxidation: experience and recommendations from an expert meeting. J Inherit Metab Dis. 2010;33(5):521-526. 3. Ultragenyx announces initiation of phase 2 study for patients with long-chain fatty acid oxidation disorders [press release]. Novato, CA: Ultragenyx Pharmaceutical Inc.; February 12, 2014. 4. MCAD and other fatty acid oxidation disorders. Illinois Department of Public Health: Genetics and Newborn Screening. Accessed August 17, 2016. 5. Roe CR, Sweetman L, Roe DS, David F, Bruengraber H. Treatment of cardiomyopathy and rhabdomyolysis in long-chain fat oxidation disorders using an anaplerotic odd-chain triglyceride. J Clin Invest. 2002;110(2):259-269. doi:10.1172/JCI200215311. 6. Fatty acid oxidation disorders. March of Dimes. Updated January 2014. Accessed August 17, 2016. 7. The National Newborn Screening and Genetics Resource Center. National Newborn Screening Report: 1999. Austin, TX:  The National Newborn Screening and Genetics Resource Center; July 2002. 8. Waisbren SE, Landau Y, Wilson J, et al. Neuropsychological outcomes in fatty acid oxidation disorders: 85 cases detected by newborn screening. Dev Disabil Res Rev. 2013;17(3):260-268. doi:10.1002/ddrr.1119. 9. Frazier DM, Millington DS, McCandless SE, et al. The tandem mass spectrometry newborn screening experience in North Carolina: 1997-2005. J Inherit Metab Dis. 2006;29(1):76-85. 10. Zytkovicz TH, Fitzgerald EF, Marsden D, et al. Tandem mass spectrometric analysis for amino, organic, and fatty acid disorders in newborn dried blood spots: a two-year summary from the New England Newborn Screening Program. Clin Chem. 2001;47(11):1945-1955. 11. LC-FAOD. Ultragenyx Pharmaceutical Inc. Accessed August 17, 2016.