Friedreich's ataxia

Friedreich’s ataxia is a relatively rare inherited condition of the nervous system, characterized by the gradual loss of coordination. A person with the condition has increasing difficulty with coordination, leading to an unsteady gait and slurred speech.

What causes Friedreich’s ataxia?#

Friedreich’s ataxia is caused by changes in a gene called FXN, located on chromosome 9. The altered gene interferes with the production of a protein called frataxin.

The condition is inherited in an autosomal recessive pattern. This means both parents carry one altered copy of the gene but have no symptoms themselves, because they also have a healthy second copy. When both parents are carriers, each of their children has a 25 per cent chance of being affected and a 50 per cent chance of being a carrier like their parents.

The symptoms are caused by the gradual deterioration of the nerve cells (neurones) in the cerebellum and spinal cord. This prevents electrical messages from passing smoothly between nerves and muscles, leading to poor coordination and movement.

How the condition progresses#

Friedreich’s ataxia progresses slowly. At first, the lack of coordination may be mistaken for clumsiness. Symptoms usually begin on average between 10 and 15 years of age, but can appear as early as four years or as late as middle age.

Most people eventually need to use a wheelchair full-time, on average around 15 years after symptoms begin. Life span may also be reduced. At this stage, medicine cannot predict how fast the condition will progress, as some people progress faster than others.

Symptoms#

Symptoms of Friedreich’s ataxia can include:

• lack of physical coordination and loss of balance
• unsteadiness on the feet, with a tendency to position the feet widely apart for balance
• unsteadiness that worsens when the person cannot see, such as in the dark
• muscle weakness as the condition progresses
• walking abnormalities and loss of tendon reflexes in the legs
• jerky, uncoordinated movements that eventually involve the arms, legs and body
• speech difficulties, such as slurring
• swallowing problems, with an associated risk of choking
• increased susceptibility to respiratory infections
• numbness and other changes in skin sensation, such as reduced ability to feel temperature, pressure or pain
• spine curvatures, such as scoliosis (where the spine curves sideways)

Heart problems and other complications#

Around two out of three people with Friedreich’s ataxia develop an associated heart problem called cardiomyopathy. The heart muscle fibers degenerate and eventually impair the heart’s function, which can cause problems such as palpitations and congestive heart failure.

Other possible complications include:

• diabetes
• vision problems, which rarely include blindness
• hearing difficulties, including deafness

Many people hear normally in a quiet environment but have significant difficulty hearing in a noisy one.

Diagnosis#

Friedreich’s ataxia is diagnosed using a number of tests, which may include:

• medical history and physical examination
• electrical nerve conduction tests
• electrocardiogram (ECG)
• echocardiogram (ultrasound of the heart)
• x-rays
• magnetic resonance imaging (MRI)
• genetic testing, which is the method used for definitive diagnosis

Treatment#

There is currently no cure for Friedreich’s ataxia. Treatment aims to ease symptoms and may include:

• exercise, such as aquatic physical therapy, to help maintain the ability to walk
• physiotherapy to help with balance, flexibility and accuracy of limb movements
• regular assessment of ataxia and muscle weakness, to enable referral to the appropriate specialists
• regular heart monitoring
• speech and language pathology to assist with speech difficulties
• maintaining a healthy weight for your height
• orthopedic aids and protective foot care
• adaptations to the home, such as wheelchair access ramps
• surgery to correct abnormal spine curvatures
• medication to reduce muscle tremors and spasms, to treat heart palpitations, and to treat diabetes, such as insulin

Research into the function of frataxin may offer potential for beneficial treatments in the future.

Genetic counseling#

If your child or another family member has been diagnosed with Friedreich’s ataxia, or if it runs in your family, it may help to speak with a genetic counselor. Genetic counselors are health professionals qualified in both counseling and genetics.

As well as offering emotional support, they can help you understand the condition, what causes it, how it is inherited, and what a diagnosis means for your child’s health and development and for your family. They are trained to provide information and support that is sensitive to your family circumstances, culture and beliefs.

If Friedreich’s ataxia runs in your family, a genetic counselor can explain the genetic testing options available to you and other relatives. You may choose to see a genetic counselor if you are planning a family, to find out your risk of passing the condition on, or to arrange prenatal tests. Genetic testing is generally recommended for parents who already have one child with the condition, as well as for other relatives. Support groups can also connect you with other individuals and families affected by Friedreich’s ataxia.

Key points#

• Friedreich’s ataxia is a rare inherited condition caused by changes in the FXN gene, which interferes with production of a protein called frataxin.
• It is inherited in an autosomal recessive pattern, so two carrier parents each have a 25 per cent chance of having an affected child.
• Symptoms include loss of coordination and balance, muscle weakness, speech and swallowing difficulties, and often heart problems such as cardiomyopathy.
• There is no cure, but treatment can ease symptoms, and genetic counseling can help families understand the condition and their testing options.

Where to get help#