Friedreich's ataxia, or FRDA, is an autosomal recessive inherited disease that causes progressive damage to the nervous system. It is the most common inherited ataxia, affecting approximately 1 in 29,000 individuals. FRDA manifests in initial symptoms of poor coordination such as gait disturbance; it can also lead to scoliosis, heart disease and diabetes, but does not affect cognitive function. The disease is progressive, and in most cases a wheelchair is required for mobility.
The particular genetic mutation (expansion of an intronic GAA triplet repeat in the FXN gene) leads to reduced expression of the mitochondrial protein frataxin. Over time, this deficiency causes the aforementioned damage, as well as frequent fatigue due to effects on cellular metabolism.
The ataxia of Friedreich's ataxia results from the degeneration of nervous tissue in the spinal cord, in particular, sensory neurons essential (through connections with the cerebellum) for directing muscle movement of the arms and legs. The spinal cord becomes thinner and nerve cells lose some of their myelin sheath (the insulating covering on some nerve cells that helps conduct nerve impulses).
The condition is named after the German physician Nikolaus Friedreich, who first described it in the 1860s.