Friedreich ataxia

Last revised by Ruben dos Reis Maia on 17 Feb 2023

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 11. Those with a higher number of trinucleotide repeats (>500) are thought to present at an earlier age and with significantly different clinical features 1.

There are a wide variety of potential clinical manifestations 11:

The condition results from an expansion of an unstable GAA trinucleotide repeat in the FXN gene located on chromosome 9q 1,6,11. 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 11. Friedreich ataxia carries an autosomal recessive inheritance 1.

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

In the brain and spinal cord:

  • may show thinning (reduction in AP diameter) of the cervical cord 2

  • cerebral and cerebellar atrophy may also be evident 5

  • 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 cerebellar peduncles 10

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

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