What is Friedreich's ataxia (FA)?
Friedreich's ataxia (FA) is a rare, progressive neurogenetic condition found in approximately 1 in 50,000 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 you decide to move your arm, nerves in your brain send an electrical signal to your spinal cord, and then peripheral nerves pass the signal on to your arm muscles. You feel your arm moving because nerves in your arm send an electrical signal back through to your brain.
In a person with Friedreich's 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 and coordination due to a decrease in the ability to identify where your limbs are in space (proprioception) — all of these are common symptoms of FA.
In most cases, ataxia is the first symptom of FA, and a person 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 motor movements of the hands and feet may become harder to execute.
People with Friedreich's ataxia may 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. Reflexes are often absent.
Other non-neurological features of the condition include issues with the heart, spine, ears, eyes and bladder.
Friedreich's 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.
Friedreich's 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 FA 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's ataxia can vary from person to person, but commonly include:
- Poor balance
- Unsteadiness while walking, especially in dark conditions
- Poor muscle coordination
- Poor gross motor skills
- Slurred speech (dysarthria)
- Decreased fine motor skills in the hands and feet (i.e. handwriting, using buttons)
- Stiffness and cramping in legs
- Decreased or absent reflexes
Other non-neurological features of the condition include:
- Hypertrophic cardiomyopathy, where the walls of the heart muscle are abnormally thick
- Heart arrhythmias (heart rhythm abnormalities)
- Scoliosis, a curvature of the spine
- Hearing loss
- Optic atrophy, damage to the optic nerve in the eye
- Urinary urgency
- Increased insulin resistance
- Increased chance of developing diabetes
Currently, there is no cure for Friedreich's 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 you or your child maximize muscle functionality and prolong walking.
A Center of Excellence
At Children's Hospital of Philadelphia, your or your child's care will be managed by our dedicated Friedreich’s Ataxia Center of Excellence. Our team focuses on managing the symptoms of Friedreich's ataxia and improving quality of life, with an emphasis on:
- Promoting normal growth and development.
- Slowing the progression of FA.
- Prevention and treatment of complications, including hypertrophic cardiomyopathy, a condition where the heart muscle is abnormally thick, and heart rhythm abnormalities. Access to CHOP's cardiology experts who specialize in treating these complications is part of the standard of care provided to patients with FA here at CHOP.
- Helping your family integrate complex care regiments into daily life.
- Accessing services to maximize independence.
- Connecting your family with educational programs.
We are constantly adjusting our approach to care based on the latest research findings and treatment approaches.
Children’s Hospital of Philadelphia is part of a network of centers around the world devoted to clinical research into Friedreich's ataxia. Our goal is to gain a better understanding of FA and its natural progression, and to use this understanding to identify better treatments.
Many new therapeutic approaches to FA are in various stages of development. We review any available clinical trials with all patients so that you have the opportunity to participate in these clinical studies if they may be of benefit to you or your child.
While Friedreich's ataxia can cause you or your child to experience significant muscle and ambulatory issues, it does not usually affect the part of the brain involved in cognition and learning. Because of this, people with FA can lead active, rewarding lives.
Reviewed by David Lynch, MD, PhD, Kim Schadt, MSN, CRNP, CCRP