Clinical Reference · Movement Disorders

Friedreich Ataxia

The most common inherited ataxia — a silenced frataxin gene
Illustration of a young patient with a wide-based ataxic gait
Progressive gait & limb ataxia
AR trinucleotide ataxia
GeneFXN (frataxin) · 9q
MutationGAA repeat in intron 1
gene silencing — not a toxic protein
InheritanceAutosomal recessive
no anticipation
OnsetUsually < 25 yrs (childhood–teens)
A young patient with progressive ataxia, absent reflexes yet upgoing toes, scoliosis, and a hypertrophic cardiomyopathy.
Key clinical features
  • Progressive gait & limb ataxia (sensory + cerebellar)
  • Areflexia with extensor plantars (the classic combo)
  • Loss of proprioception & vibration (dorsal columns)
  • Dysarthria, fixation nystagmus, square-wave jerks
  • Skeletal: scoliosis, pes cavus
  • Optic atrophy & sensorineural hearing loss
◆ Signature clue

Areflexia + upgoing toes in a young patient with scoliosis and hypertrophic cardiomyopathy → Friedreich until proven otherwise. Cardiomyopathy is the leading cause of death; ~30% develop diabetes.

Diagnosis
GAA-repeat testing of FXN confirms it. Baseline ECG + echo (HCM) and glucose/HbA1c — the systemic complications that kill.
Management
Omaveloxolone (Skyclarys, 2023) — first FDA-approved, modestly slows progression. Plus PT, cardiac & diabetes surveillance, scoliosis care.
Board pearlThe only trinucleotide-repeat disease that is autosomal recessive and caused by gene silencing (not a toxic gain-of-function) — which is why it shows no anticipation.
Sources: Neuro.Wiki › Movement Disorders / Friedreich Ataxia. Educational reference — not a substitute for clinical judgment. Neuro.Wiki