Diagnosis and Prognosis
FA is usually diagnosed by genetic testing. Approximately 75% of people with FA are diagnosed between six and 20 years of age. Typically, the most common symptom is loss of balance and coordination, which usually occurs between five to 15 years of age.5
People with FA experience progressive loss of coordination, muscle weakness, and fatigue, which commonly leads to wheelchair reliance.1,6 Because FA is a multisystem disease, individuals may also experience visual impairment, hearing loss, skeletal abnormalities, diabetes, and cardiomyopathy.6,7 Childhood-onset FA is more common than later-onset FA, and is usually marked by rapid disease progression, which can occur as early as five years of age.6-8
Most individuals with FA experience disease onset between approximately 13 to 15 years of age, and often require use of a wheelchair within 10 to 15 years.6-8 The mean age of death is 35 years, and more than half of these deaths are caused by cardiac complications.6
FA is characterized by a decrease in frataxin expression, which is caused by the transcriptional silencing of the FXN gene. A deficiency of frataxin in cells leads to mitochondrial iron overload and poor cellular iron regulation, increased sensitivity to oxidative stress, and mitochondrial dysfunction that impairs ATP production.1,4,7 Impaired ATP production likely accounts for the decreased coordination, progressive muscle weakness, exercise intolerance, and fatigue observed in patients with FA, as well as other disease manifestations.