Friedreich's Ataxia

  • What is Friedreich ataxia (FA)?

    Friedreich ataxia (FA) is a rare, progressive neurogenetic condition found in approximately 1 in 40,000 people worldwide. While FA is relatively rare, it is the most common form of inherited ataxia. It is sometimes confused with spinocerebellar ataxia, a different group of inherited ataxias.

    FA affects the function of the cerebellum, the part of the brain that helps plan and coordinate movements. For example, when your child decides to move her arm, nerves in her brain send an electrical signal to her spinal cord, and then peripheral nerves pass the signal on to her arm muscles. Your child feels her arm moving because nerves in her arm send an electrical signal back through to her brain.

    In a child with Friedreich ataxia, this flow of sensory information — particularly through the peripheral nerves and the spinal cord — is severely affected. The loss of nerve sense leads to poor balance, coordination and muscle strength — all of which are common symptoms of FA.

    In most cases, ataxia is the first symptom of FA, and a child with the disorder will have general unsteadiness when walking and will often trip or stumble - especially in dark conditions. Over time, speech may change and become more slurred, handwriting may become less clear, and fine movements of the hands and feet may become harder to execute.

    People with Friedreich ataxia will eventually become unable to stand without losing their balance and will require assistive devices such as walkers, wheelchairs or scooters to remain mobile. Some people with FA experience stiffness and cramping in their legs, and muscles may weaken over time. Reflexes are often absent.

    Other non-neurological features of the condition include issues with the heart, spine, ears, eyes, bladder and kidneys.

    Friedreich ataxia does not affect the part of the brain involved in cognition and learning.

    In most cases, FA begins during childhood, but it can present later in life, even well into adulthood. Late-onset FA can produce different symptoms and requires different medical management.

  • Causes

    Friedreich ataxia is caused by alterations, or mutations, in the frataxin (FXN) gene located on chromosome 9. Genes are specific instructions for making proteins, which provide structure to cells and drive the chemical reactions inside them.

    In the vast majority of FA cases (more than 95 percent), this alteration is an increased number of DNA bases (known as the “GAA trinucleotide repeat”) in a specific region at the beginning of the gene. This alternation acts like a roadblock. It prevents the proper reading of the gene and stops frataxin from being made and assembled.

    In other cases (less than 5 percent), a change in a single DNA base can cause an error in the genetic instructions, so the frataxin protein made from these instructions is not normal.

    In either case, individuals with FA have two altered copies of the frataxin gene, so they are unable to make the normal amount or type of frataxin. People with only one altered copy of the gene are called “carriers” — they have no symptoms of the disorder but can pass it along to their children. Approximately 1 in every 120 people of Western European descent is a carrier for FA.

  • Signs and symptoms

    Symptoms of Friedreich ataxia can vary from child to child, but may include:

    • Poor balance
    • Unsteadiness while walking
    • Increased tripping, especially in dark conditions
    • Poor muscle coordination
    • Poor gross motor skills
    • Diminished muscle strength
    • Slurred speech (dysarthria)
    • Decreased fine motor skills in the hands and feet (i.e. handwriting, using buttons)
    • Stiffness and cramping in legs
    • Delayed or absent reflexes

    Other non-neurological features of the condition include:

    • Hypertrophic cardiomyopathy, an increase in size of the walls of the heart
    • Heart arrhythmias
    • Scoliosis, a spinal deformity
    • Hearing loss
    • Optic atrophy, damage to the optic nerve in the eye
    • Urinary urgency
    • Increased insulin sensitivity
    • Increased chance of developing diabetes
  • Treatment

    Currently, there is no cure for Friedreich ataxia. However, there are some prescription medications and over-the-counter supplements that can help manage some of the symptoms of the condition.

    In addition, physical therapy and regular exercise can help your child maximize his muscle functionality and prolong walking.

  • Research

    The Children’s Hospital of Philadelphia is part of a network of centers around the world devoted to clinical research on Friedreich ataxia. Many new therapeutic approaches to FA are in various stages of development.

    Our recent and ongoing studies are either self-funded or are funded by the Friedreich Ataxia Research Alliance (FARA).   

  • Outlook

    While Friedreich ataxia can cause your child to experience significant muscle and ambulatory issues, it does not affect the part of the brain involved in cognition and learning. Because of this, your child with FA can lead an active, rewarding life. She can go to college, have a career, get married, and start a family.

    In fact, a retrospective study of women with FA conducted at CHOP found these women were no more likely to have a serious pregnancy complication than women without the disorder. They were able to successfully carry their pregnancies to term.

Reviewed on May 09, 2014