- Autosomal recessive
- Frataxin gene chr. 9. Protein= Frataxin. GAA nucleotide repeat (normal repeat number is 6-27). Compound heterozygotes occur in 5%.
- Ataxia & dysarthria
- Areflexia, extensor plantars
- Hammer toes arched foot, scoliosis
Gross: atrophy of spinal cord. Grey discolouration of posterior & lateral aspects of the spinal cord. Small sensory nerve roots.
Microscopically: Brain stem: atrophy of the dentate nucleus and superior cerebellar peduncle. Neuronal loss in vestibular and cochlear nuclei. Spinal cord: degeneration of posterior columns, spinocerebellar tracts and corticospinal tracts. Neuronal loss in Clarkes column. Dorsal root ganglia: neuronal loss.
Findings on investigations:
Fasting blood glucose: diabetes mellitus
ECG: conduction defects
Consider Co-enzyme Q, Vitamin E