Genetics
Friedreich's ataxia (FRDA), in almost all cases is caused by a mutation in FXN (previously called X25 and FRDA).
- in majority of FRDA cases (about 96%), there is homozygosity for a pathological expansion of a GAA trinucleotide repeat in intron one of FXN while in the other 4%, there is compound heterozygosity for an intron one GAA repeat expansion in one allele and a point mutation or deletion in the other (1)
The gene FXN codes for the protein frataxin.
- GAA expansion results in a reduction of frataxin
- frataxin is a mitochondrial membrane protein involved in iron sulfur protein production, storage and transport
The Friedreich's ataxia mutation results in iron overload in mitochondria and neuronal death.
Reference:
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