Learn About LC-FAOD

Understand What Causes LC-FAOD and How It Impacts the Body

Understand What Causes LC-FAOD and How It Impacts the Body

What are long-chain fatty acid oxidation disorders (LC-FAOD)?

LC-FAOD are rare, genetic metabolic disorders that prevent the body from breaking down long-chain fatty acids into energy during metabolism.

LC-FAOD are inherited genetic conditions.

Fatty acid oxidation disorders (FAOD) are inherited conditions. For each condition, an enzyme that helps the body use stored fat for energy is missing or defective.

LC-FAOD disrupt normal metabolism.

Enzymes help the body convert fat into fatty acids and then into energy. When the body can’t convert fat into energy as it should, levels of fatty acids build up in the heart, liver, and other organs.

LC-FAOD have recognizable signs and symptoms.

Breakdown of fatty acids is necessary for energy production when sugar, or glucose, levels are low. Without this energy supply, people with LC-FAOD may have symptoms that include, but are not limited to muscle pain, muscle weakness, low blood sugar, and fatigue.

Genetics Shape Hereditary Disorders

Hereditary metabolic disorders, including LC-FAOD, develop when children inherit defective genes that control metabolism. LC-FAOD are inherited in an autosomal recessive manner.

Autosomal recessive describes the way the genes are passed down. An autosomal recessive disorder means two copies of an abnormal gene must be present for the disease to develop.

To inherit LC-FAOD, both parents must be carriers.

Each child inherits two copies of the abnormal gene—one from each parent.

With each pregnancy, parents have a:

  • 25% chance of having an affected child with two abnormal copies of the gene (left)
  • 50% chance of having an unaffected child who is also a carrier (middle)
  • 25% chance of having an unaffected child with two normal copies of the gene (right)
Autosomal recessive disorder inheritance graphic

Metabolism Is Essential to Life

Metabolism is how the body breaks down and converts food into energy.

Simplified metabolism disruption graphic

In metabolism, enzymes are needed to enable specific chemical reactions. Several specific enzymes help break down fats so that they may be turned into energy.

Simplified metabolism disruption graphic

Fatty acid oxidation disorders are metabolic disorders that are caused by a lack, or defect, of the enzymes needed to break down fats.

Simplified metabolism disruption graphic

Metabolism is disrupted when an enzyme that helps the body use stored fat for energy is missing or defective.

Once glucose (sugar) is gone, the body tries to use fat without success, which disrupts energy homeostasis and leads to clinical symptoms because of the ineffective enzyme(s) present in LC-FAOD.

Be Ready to Recognize the Signs and Symptoms

Chronic symptoms and acute episodes

LC-FAOD are serious conditions, and people diagnosed with LC-FAOD are at risk of developing severe symptoms or health complications that can be life-threatening.

Research has found that the life expectancy of individuals diagnosed with LC-FAOD is significantly negatively impacted and that the swift development of symptoms can lead to sudden death.

It is essential that patients and caregivers develop a protocol or regimen with their healthcare provider to use in emergency situations.

Chronic (persistent or recurring) symptoms may include fatigue, muscle pain, muscle cramps, muscle weakness, and foggy thinking.

Chronic symptoms can be brought on or made worse by fasting, illness, sustained exercise, and physiologic stress and may lead to the following:

  • Decreased muscle tone and weakness (hypotonia)
  • Damage to the retina of the eyes (retinopathy)*
  • Damage to the nerves outside the brain and spinal cord (peripheral neuropathy)*

*Applies to certain LC-FAOD types such as LCHAD and TFP. Consult your healthcare provider for more information.

Acute episodes can be triggered by illness or fasting, but they may also occur spontaneously and unpredictably.

Acute episodes may lead to hospitalization, emergency room visits, and emergency interventions, with the risk of sudden death.

With LC-FAOD, individuals might experience acute metabolic crises that may include serious conditions such as:

  • Heart muscle damage (cardiomyopathy)
  • Muscle breakdown (rhabdomyolysis)
  • Low glucose, ie, low sugar (hypoglycemia)

Individuals with LC-FAOD may limit their physical activity because sustained intense exercise or activity increases the risk of developing symptoms or triggering an acute episode.

May have a chronic impact.

Issues in Infants and Young Children

Caregivers of babies and young children with LC-FAOD should watch for and be aware of symptoms of a metabolic crisis, including:

  • Neurologic distress (extreme sleepiness, coma, Reye’s syndrome)
  • Changes in heart beat
  • Muscle weakness
  • Changes in appetite or dietary requirements

Keep a record and let your healthcare team know if you experience or observe any of these signs or symptoms.

Useful Resources

Medical History

Keeping an up-to-date medical history and providing copies to your healthcare team can help make the most of your office visits.


Communicating with Healthcare Providers

People with LC-FAOD may need to see multiple healthcare providers. This guide has tips on how to improve the communication between you and each professional.


People with LC-FAOD face significant challenges, and those who care for them have ongoing responsibilities

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