Friedreich's ataxia

From Ganfyd

Friedreich ataxia is one of the most common autosomal recessive disorders. The two most common forms are

• FRDA1 frataxin (FXN) gene mutation at 9q13 (usually GAA trinucleotide repeat expansion of intron 1 for 70 to more than 1,000 GAA triplets)
• FRDA2 gene mutation at 9p23-p11

Diagnosis

1. Hypoactive knee and ankle jerks
2. Progressive cerebellar dysfunction
3. Preadolescent onset

• Genetics (especially if triad above not present !)

Clinical presentation

Fatigue.

• Cerebellar signs
  • Incoordination of limbs
  • Dysarthria
  • Nystagmus
• Long tract signs
  • Reduced or absent deep tendon reflexes
  • Upgoing plantars
  • Impaired position and vibratory sense
  • Motor and sensory nerve conduction abnormalities
• Skeletal signs
  • Scoliosis
  • Pes cavus
  • Hammer toe.
• Hypertrophic cardiomyopathy

There are late onset forms (the upper limit of normal GAA repeats is about 40 at intron 1) which may not exhibit the scoliosis or other features. A form with normal reflexes is known.(Friedreich Ataxia with Retained Reflexes, FARR), as is one with chorea as the presenting picture (but FRDA1 genetics).

Treatment

• Idebenone is being used experimentally in Canada. The effectiveness is said to be mainly on the heart.

Prognosis

The disease causes death but the rate of progression is variable.

Occupation

Changes to jobs, and of occupation are likely to be necessary.