friedreich ataxia

Friedreich ataxia is the most common hereditary progressive ataxia.


Thought to have an estimated prevalence of ~1:50,000. There is no recognized gender predilection.

Typically present in childhood to adolescence . Those with a higher number of trinucleotide repeats (>500) are thought to present at an earlier age and with significantly different clinical features .

Clinical presentation

There are a wide variety of potential clinical manifestations :



The condition results from an expansion of an unstable GAA trinucleotide repeat in the FXN gene located on chromosome 9q . This gene encodes for frataxin, a protein that has multiple important roles in relation to iron in various tissues of the body, but most prominently the brain, heart and pancreas . Friedreich ataxia carries an autosomal recessive inheritance .

Microscopic appearance

In the posterior and lateral columns of the spinal cord, there is a loss of myelinated fibers and gliosis.

Radiographic features


In the brain and spinal cord:

  • may show thinning (reduction in AP diameter) of the cervical cord
  • cerebral and cerebellar atrophy may also be evident
  • DWI is a suitable non-invasive technique to quantify the extent of neurodegeneration in Friedreich ataxia, that appears more extended than previously reported, showing a microstructural involvement of structures such as optic radiation and middle cerebral peduncle

History and etymology

It is named after Nikolaus Friedreich (1825-1882), a German physician.

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