Friedreich ataxia

- autosomal recessive trinucleotide repeat disorder (GAA repeat)
- most common form of hereditary ataxia
- mutation in gene encoding protein frataxin on chromosome 9
- presents with progressive ataxia, cerebellar dysfunction, pyramidal weakness and sensory motor neuropathy
- other features: pes cavus, optic atrophy, hypertrophic cardiomyopathy (50-70% patients)