Signs and Symptoms
FA affects 1:30 000 people in Australia and New Zealand. Most individuals have onset of symptoms of FA between the ages of 5 and 18 years old. Adult or late onset FA is less common and can occur anytime during adulthood.
Symptoms that usually occur:
- Loss of co-ordination in arms and legs (Ataxia)
- Fatigue- Energy deprivation and muscle loss
- Vision impairment, hearing loss and slurred speech
- Aggressive scoliosis (Curvature of the spine)
- Diabetes mellitus (Insulin dependent usually)
- serious heart conditions, including hypertrophic cardiomyopathy and arrthymias
These symptoms are not present in all individuals with FA, for example diabetes occurs in about 10-20% of individuals with FA. The mental capabilities of people with Friedrichs Ataxia remain completely intact. The progressive loss of coordination and muscle strength leads to motor incapacitation and the full-time use of a wheelchair. Most young people diagnosed with FA require mobility aids such as a cane, walker, or wheelchair by their teens or early 20s.
How does FA occur?
Friedreich’s Ataxia aka FA, is an inherited or single gene disorder. Mutations or DNA changes in the FXN gene cause FA.
FA is inherited in an autosomal recessive manner, meaning that individuals with FA have two mutated or abnormal copies of the FXN gene, this means both biological parents must be a carrier of the disease for a child to be affected. It is estimated that 1 in 100 people are carriers, and carriers do not exhibit symptoms of FA. Each such carrier parent has one mutated gene (allele) and one normal gene (allele) in the FXN gene. Because each child gets one of the mother’s genes and one of the father’s genes in this location, there are four possible combinations of the genes passed down to the child or a 25% chance that the child will have FA.
The FA gene mutation limits the production of a protein called Frataxin. Frataxin is known to be an important protein that functions in the mitochondria (the energy producing factories) of the cell. Frataxin helps to move iron and is involved with the formation of iron-sulfur clusters, which are necessary components in the function of the mitochondria and thus energy production. We also know that specific nerve cells (neurons) degenerate in people with FA, and this is directly manifested in the symptoms of the disease.