Friedreich ataxia is an autosomal recessive neurodegenerative disorder characterized by impaired muscle coordination (ataxia), gradual loss of strength and sensation in the arms and legs, muscle stiffness and problems in speech, hearing, and vision. People with Friedreich ataxia often have hypertrophic cardiomyopathy, a form of heart disease. Diagnosis is usually made between ages 5 and 15; poor coordination and balance are usually among the first symptoms.
Carrier frequency is estimated to be from 1/60 to 1/120 and the frequency of affected individuals is 1-2/50.000 people.
Approximately 95% of cases are caused by a homozygous expansion of trinucleotide GAA located in the first intron of frataxin, FXN, gene. Unaffected indiciduals have 6-36 GAA repeats, while affected people have 66 up to more than 1000 repeats. The number of the GAA trinucleotide repeats is correlated to the age at which the symptoms of Friedreich ataxia appear, how severe they are, and how quickly they progress.
The remaining 5% of cases is caused by homozygous or compound heterozygous mutations in frataxin, FXN, gene, or combination of a pathological allele with expanded GAA repeats and a mutation in the other allele of the gene.
The number of GAA repeats in FXN gene is analysed using PCR and subsequent fragment analysis in a Genetic Analyser.
Sample type: Peripheral blood in EDTA
Time to result: 2 weeks
Upon negative results or other clinical indication, analysis of the coding region of FXN gene by next generation sequencing can be performed as an additional test.
Prenatal diagnosis for Friedreich ataxia is possible, please contact us for more information.