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Genetic and Rare Diseases Information Center (GARD)

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Friedreich ataxia

Other Names for this Disease
  • FRDA
  • Friedreich's ataxia
  • Hereditary spinal ataxia
  • Hereditary spinal sclerosis
  • Spinocerebellar ataxia, Friedreich
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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 a defect in a gene called Frataxin (FXN), which 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: 1/23/2012

How is Friedreich ataxia inherited?

Friedreich ataxia is inherited in an autosomal recessive pattern, which means that both copies of the FXN gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene (and are referred to as carriers); but they typically do not show signs and symptoms of the condition. When two people who are carriers of an autosomal recessive condition have a child, each time there is a 25% (1 in 4) chance that the child will have the condition, a 50% (1 in 2) chance that the child will be a carrier like each of the parents, and a 25% (1 in 4) chance that the child will not have the condition and not be a carrier.[1]
Last updated: 1/23/2012

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

Is genetic testing available for Friedreich ataxia?

Yes, genetic testing is available to look for expanded GAA triplet-repeat mutations in the FXN gene. GeneTests lists the names of laboratories that are performing genetic testing for Friedreich ataxia. To view the contact information for the clinical laboratories conducting testing, click herePlease note:  Most of the laboratories listed through GeneTests do not accept direct contact from patients and their families; therefore, if you are interested in learning more, you will need to work with a health care provider or a genetics professional.  Below, we provide a list of online resources that can assist you in locating a genetics professional near you.
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: 10/18/2013