Friedreich-Ataxie
Friedreich ataxia is the most common hereditary progressive ataxia.
Epidemiology
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 :
- neurological
- cerebellar and spinocerebellar tract involvement: four-limb ataxia, gait ataxia, cerebellar dysarthria
- lateral corticospinal tract involvement: upper motor neuron pattern weakness
- dorsal columns involvement: vibration and proprioceptive loss
- dorsal root ganglia involvement: areflexia
- musculoskeletal
- hypertrophic cardiomyopathy
- diabetes mellitus
Pathology
Genetics
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
MRI
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.
Siehe auch:
Assoziationen und Differentialdiagnosen zu Friedreich-Ataxie:
