Friedreich ataxia (FRDA) is an autosomal recessive disorder characterized by neurodegeneration and cardiomyopathy, and is the most common inherited ataxia. About 98% of individuals with FRDA are homozygous for an expansion of a GA A trinucleotide repeat sequence within the first intron of the FXN gene. The remaining individuals are compound heterozygotes for a GAA expansion and a point mutation. Pathogenic GAA expansion alleles are in the size range of 60 to >1300 repeats. The presence of a GAA repeat expansion results in the inhibition of FXN gene expression, reduced levels of full-length FXN transcript, and an insufficiency of the mitochondrial protein frataxin (1–4). Overall, an inverse correlation has been found between the size of the smaller GAA expansion and transcript levels, the amount of residual frataxin produced, and the age of onset of disease symptoms (5–9).

Detection of interruptions in the GAA trinucleotide repeat expansion in the FXN gene of Friedreich ataxia

Friedreich's ataxia (FRDA) is the most common hereditary ataxia among caucasians. The molecular defect in FRDA is the trinucleotide GAA expansion in the first intron of the FXN gene, which encodes frataxin. No studies have yet reported frataxin protein and mRNA levels in a large cohort of FRDA patients, carriers and controls.

A combined nucleic Acid and protein analysis in friedreich ataxia: implications for diagnosis, pathogenesis and clinical trial design

Friedreich ataxia (FRDA) is the commonest form of autosomal recessive ataxia. This study aimed to define the extent of the brain damage in FRDA patients and to identify in vivo markers of neurodegeneration, using diffusion-weighted imaging (DWI).

Brain diffusion-weighted imaging in Friedreich's ataxia

Friedreich's ataxia is a multisystem disorder of mitochondrial function affecting primarily the heart and brain. Patients experience a severe cardiomyopathy that can progress to heart failure and death. Although the gene defect is known, the precise function of the deficient mitochondrial protein, frataxin, is not known and limits therapeutic development. 

Cardiomyopathy of Friedreich's Ataxia: Use of Mouse Models to Understand Human Disease and Guide Therapeutic Development