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FXN gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

FXN gene

The FXN gene provides instructions for making frataxin, a protein essential for energy production and iron regulation within cells.

Normal Function

The FXN gene provides instructions for making a protein called frataxin. This protein is found in cells throughout the body, with the highest levels in the heart, spinal cord, liver, pancreas, and skeletal muscles. Within cells, frataxin is found in energy-producing structures called mitochondria.

Frataxin appears to help assemble clusters of iron and sulfur molecules that are critical for the function of many proteins, including those needed for energy production. One region of the FXN gene contains a segment of DNA known as a GAA trinucleotide repeat. In most people, this segment is repeated fewer than 12 times (short normal), while 12 to 33 repeats is considered long normal.

Health Conditions Related to Genetic Changes

Friedreich ataxia

Friedreich ataxia results from an increased number of copies (expansion) of the GAA trinucleotide repeat in the FXN gene. In people with this condition, the GAA segment is abnormally repeated 66 to more than 1,000 times.

  • Age of onset: The length of the repeat is related to the age at which symptoms appear. People with fewer than 300 repeats tend to have a later onset (after age 25).
  • Inheritance: Most individuals have the expanded repeat in both copies of the FXN gene. About 2 percent have an expansion in one copy and a different mutation in the other.

Mutations in this gene disrupt the production of frataxin, reducing the amount of this protein in cells. A shortage of frataxin decreases the activity of proteins containing iron-sulfur clusters, impairing energy production. Furthermore, cells with insufficient frataxin are sensitive to free radicals, which can damage and destroy cells in the brain, spinal cord, and muscles.

Other Names for This Gene

  • CyaY
  • FA
  • FARR
  • FRDA
  • FRDA_HUMAN
  • Friedreich ataxia
  • MGC57199
  • X25

Frequently Asked Questions

The repeat length is measured by PCR‑based sizing or Southern blot analysis of DNA from blood. The number of GAA repeats correlates with disease severity and age of onset: repeats  600 are linked to early‑onset, rapidly progressive disease.
Friedreich ataxia is typically recessive, requiring pathogenic changes in both copies of the FXN gene. A single expanded allele (carrier) usually does not cause disease, but carriers have a 1‑in‑2 chance of passing the expanded allele to each child. If the partner is also a carrier, there is a 25 % chance their child will inherit two expanded alleles and develop the disease.
Baseline evaluation includes an electrocardiogram (ECG) and transthoracic echocardiogram to detect hypertrophic cardiomyopathy, a common complication. Follow‑up imaging is recommended every 1‑2 years, or sooner if symptoms (e.g., shortness of breath, palpitations) appear. Cardiac MRI may be added for detailed assessment in progressive cases.
No cure exists, but multidisciplinary care can improve quality of life. Physical therapy and regular aerobic exercise help maintain balance and muscle strength. Idebenone and other antioxidant agents have shown modest benefits in some trials, though they are not universally approved. Cardiac medications (e.g., ACE inhibitors) are used if cardiomyopathy develops. Nutritional support, diabetes screening, and speech therapy are also part of comprehensive management.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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