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Diseases

Genetic and Rare Diseases Information Center (GARD)

Friedreich ataxia


Other Names for this Disease
  • Friedreich's ataxia
  • Spinocerebellar ataxia, Friedreich
  • Hereditary spinal sclerosis
  • Hereditary spinal ataxia
  • FRDA
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.

Your Question

My 32-year-old brother has Friedreich ataxia and is completely dependent and wheelchair bound. I have lived a normal, healthy life but have read recently that late onset of this condition can occur in individuals from 26 years and older. I am currently 33-years-old. What are my chances of developing Friedreich ataxia later on in life? Should I get tested for it?

Our Answer

We have identified the following information that we hope you find helpful. If you still have questions, please contact us.

What causes Friedreich ataxia?

Friedreich ataxia is caused by mutations in the FXN gene. This gene provides instructions for making a protein called frataxin. One region of the FXN gene contains a segment of DNA known as a GAA trinucleotide repeat. This segment is made up of a series of three DNA building blocks (one guanine and two adenines) that appear multiple times in a row. Normally, this segment is repeated 5 to 33 times within the FXN gene. In people with Friedreich ataxia, the GAA segment is repeated 66 to more than 1,000 times. The length of the GAA trinucleotide repeat appears to be related to the age at which the symptoms of Friedreich ataxia appear.[1]

The abnormally long GAA trinucleotide repeat disrupts the production of frataxin, which severely reduces the amount of this protein in cells. Certain nerve and muscle cells cannot function properly with a shortage of frataxin, leading to the characteristic signs and symptoms of Friedreich ataxia.[1]
Last updated: 5/22/2015

How is Friedreich ataxia inherited?

Friedreich ataxia is inherited in an autosomal recessive manner.[1] This means that to be affected, a person must have a mutation in both copies of the responsible gene in each cell. The parents of an affected person usually each carry one mutated copy of the gene and are referred to as carriers. Carriers typically do not show signs or symptoms of the condition. When two carriers of an autosomal recessive condition have children, each child has a 25% (1 in 4) risk to have the condition, a 50% (1 in 2) risk to be a carrier like each of the parents, and a 25% chance to not have the condition and not be a carrier.
Last updated: 11/19/2015

Can individuals with Friedreich ataxia develop symptoms later in life?

Yes. Symptoms typically begin between the ages of 5 and 15 years, although they sometimes appear in adulthood and on rare occasions as late as age 75.[2] In about 15% of individuals with Friedreich ataxia, the onset of symptoms is later than age 25 years. In people with late-onset Friedreich ataxia (LOFA), signs and symptoms of the disease occur between 26-39 years.  In very late-onset Friedreich ataxia (VLOFA), symptoms usually occur after age 40. Disease progression is usually slower in late-onset forms as compared to typical Friedreich ataxia, including a later age of needing a wheelchair and lower incidence of skeletal abnormalities (e.g., scoliosis, pes cavus,clubbing of the feet).[3]

People with LOFA frequently have fewer than 500 GAA repeats in at least one of the expanded alleles. Those with VLOFA usually have fewer than 300 GAA repeats in at least one of the expanded alleles. However, one study reported an individual with VLOFA who had GAA expansions greater than 800 GAA repeats, underscoring the inability to predict the outcome in each individual. In general, repeat lengths of 100-300 repeats are often associated with LOFA and VLOFA.[3]
Last updated: 1/23/2012

How can I find a genetics professional in my area?

Genetics clinics are a source of information for individuals and families regarding genetic conditions, treatment, inheritance, and genetic risks to other family members. More information about genetic consultations is available from Genetics Home Reference. To find a genetics clinic, we recommend that you contact your primary healthcare provider for a referral.

The following online resources can help you find a genetics professional in your community:
Last updated: 6/5/2014

References
Other Names for this Disease
  • Friedreich's ataxia
  • Spinocerebellar ataxia, Friedreich
  • Hereditary spinal sclerosis
  • Hereditary spinal ataxia
  • FRDA
See Disclaimer regarding information on this site. Some links on this page may take you to organizations outside of the National Institutes of Health.