Friedreich’s ataxia (FA) is a rare genetically inherited disorder. It manifests itself in the form of progressive impairment of muscle coordination (ataxia), loss of muscle strength and sensation, and impaired speech, vision, and hearing. The disease is characterized by a slow progression and, in general, rather poor prognosis. Individual prognosis depends on many factors, including specific genetic changes behind the condition, the age of disease onset, the severity of symptoms, and the presence of other illnesses.
The genetic cause of the disease is the expansion of a trinucleotide repeat (GAA) in a gene called frataxin (FXN), which encodes for a protein that is required for the normal functioning of the mitochondria (the energy factories of the cells). The trinucleotide repeats are present in small numbers (between five and 33 times) in healthy people. But in people with FA, the number of repeats can be as many as 1,000. The expansion of repeats reduces the production of frataxin protein, disrupting the functions of the mitochondria, and leading to the symptoms of the disease.
The factors affecting the prognosis of Friedreich’s ataxia, includes age of disease onset, severity of symptoms, and comorbidities.
Age of onset
The age of onset of the disease varies substantially among patients. Most patients (75-85 percent) are diagnosed with FA before the age of 25 years. Onset at a very young age (before age 5) is exceptionally rare. Around 25 percent of patients have an atypical presentation with the onset of disease at older ages. Approximately 15 percent of cases are diagnosed between ages 26 and 39 (called late-onset Friedreich’s ataxia (LOFA)), and a further 12 percent of cases are diagnosed after age 40. This is called very late onset Friedreich’s ataxia (VLOFA).
The age of onset and prognosis is linked to the number of trinucleotide repeats, with patients with a lower number of repeats (less than 300) developing the disease later in life, having less severe symptoms, and usually living longer.
In general, the age of disease onset correlates with life expectancy. People with earlier onset disease tend to manifest more severe symptoms and die younger. Most patients with FA survive until the ages 40-50, although life expectancy varies significantly depending on the severity of the symptoms. People with LOFA and VLOFA tend to have milder symptoms and survive longer.
Other illnesses and complications
The most common problem (and the cause of death in 59 percent of patients) is cardiac dysfunction, such as arrhythmia and congestive heart failure. Patients with cardiac dysfunctions tend to die earlier — on average, 17 years after the disease’s onset. Patients without disease-associated heart problems live longer and survive, on average, for 29 years after onset of the disease.
About 10 percent of FA patients develop diabetes. There also are other possible complications associated with the disease, including scoliosis (curvature of the spine) and problems with digesting carbohydrates. The presence of complications also may affect the prognosis of patients.
An overwhelming majority (95 percent) of patients eventually lose the ability to walk (on average, 15 years after the onset of the disease) and need to use a wheelchair by the age of 45.
Although FA cannot be cured, adequate symptomatic treatments (such as treatment of heart problems and diabetes, and orthopedic interventions) help reduce the severity of the complications and other risks associated with the disease, and subsequently extend the life span of patients.
Note: Friedreich’s Ataxia News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.