Friedreich's ataxia is an inherited disease that is characterized by a progressive degeneration of the spinal cord and nerve tissue. Caused by a mutated gene region on chromosome 9 that results in mitochondrial malfunction, Friedreich's ataxia can lead to a variety of conditions including speech problems, vision impairment, muscle weakness, diabetes and scoliosis. X123, also known as C9orf61 (chromosome 9 open reading frame 61), is a 289 amino acid protein that is expressed at high levels in skeletal muscle and at lower levels in brain, heart and lung. The gene encoding X123 is located within the Friedreich's ataxia region on chromosome 9, suggesting a possible role for X123 in the pathogenesis of this disease.