What is Friedreich Ataxia

FA is inherited in an autosomal recessive pattern, which means that in order for a child to be affected, they must inherit two abnormal copies of the FXN gene, one from each parent. The parents, who each have one abnormal copy of the FXN gene are known as ‘carriers’, do not have any symptoms of FA and usually don’t know that they are carriers. If both parents are carriers, they have a 1 in 4 chance of having an affected child. About 1 in 90 people of Caucasian background is a carrier of the FA gene. FA can be diagnosed via a genetic test.

Symptoms usually begin between the ages of 5 and 15 but can appear as early as 18 months, or as late as 40 or 50 years of age. About a quarter of people have what is considered late-onset FA with symptoms appearing after the age of 25. There is a lot of variability from person to person in the age of onset, severity, and range of symptoms experienced. The main symptoms include muscle weakness and ataxia, which is a loss of balance and coordination. FA doesn’t affect a person’s cognitive ability.

The first symptom is usually difficulty in walking which may be noticed as frequent tripping or an unsteady walk. Before diagnosis, people with FA are often considered ‘clumsy’. Balance and coordination continue to decline over time, and muscles in the legs are easily fatigued, making it increasingly difficult to walk. Most people with FA will need the aid of a wheelchair sometime between 10-20 years after symptoms begin. As FA progresses, problems with speech and swallowing may start to appear due to tongue and facial muscle weakness. Everyday tasks like writing, dressing, cooking and eating become more difficult. FA can also lead to hearing loss or visual impairment, for some. Foot deformity is also a common problem and about two-thirds or people with FA develop curvature of the spine (scoliosis). Other possible serious complications include heart problems and diabetes.

Friedreich Ataxia is caused by changes (sometimes called mutations) in the FXN gene which contains the instructions for making frataxin protein. Normally, the gene contains five to 30 repeats of a three-letter code, but in people with FA, the gene contains hundreds of these repeats. The frataxin protein has an important role in energy production in the energy factories of the cell, which are called mitochrondria. Iron is essential for energy production in the mitochrondria and it is thought that frataxin acts as a storage vessel for iron and releases it only when it is needed. If frataxin is missing or defective, excess iron is left floating around which stresses and damages the mitochrondria. This stress is known as oxidative stress - the build-up of harmful oxygen-based free radicals.

Mitochrondria act as an essential energy source for nearly all of the cells in our bodies, which probably explains why FA affects many different parts of the body including the muscles, nervous system and heart. It is also thought that these parts of the body may be particularly susceptible to damage by free radicals.