Friedreich Ataxia

Summary

Friedreich ataxia is a neurodegenerative disease affecting the corticospinal tract, spinocerebellar tract, dorsal column, and the dorsal root ganglia. It is an autosomal recessive inherited disease caused by expansion of a GAA trinucleotide repeat in the frataxin gene of chromosome 9. This mutation leads to sensory loss and impaired muscle coordination, contributing to symptoms like ataxia, frequent falling, dysarthria, or nystagmus. Friedreich ataxia is also often associated with diabetes, hypertrophic cardiomyopathy, kyphoscoliosis, and foot deformities like pes cavus and hammer toes. 

Key Points

• Friedreich Ataxia
  • Genetics
    • Trinucleotide repeat disorder with GAA repeats
      • Mutation in frataxin (iron binding protein) on chromosome 9
    • Autosomal recessive inheritance
  • Pathophysiology
    • Neurological degeneration of multiple structures
      • (Lateral) Corticospinal tract
        • Leads to spastic paralysis
      • Spinocerebellar tract
        • Leads to ataxia
      • Dorsal column
        • Leads to loss of proprioception and vibration sense
        • Contributes to ataxia
      • Dorsal root ganglia
        • Leads to loss of DTRs/areflexia
  • Presentation
    • Staggering gait / ataxia
    • Frequent falling
      • Secondary to sensory and motor abnormalities
    • Nystagmus
    • Dysarthria
    • Diabetes mellitus
    • Hypertrophic cardiomyopathy
    • Kyphoscoliosis
    • Foot deformities
      • Pes cavus
      • Hammer toes