Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS).

Individuals carrying an FMR1 expansion between 55 and 200 CGG repeats, are at risk of developing the Fragile X-associated tremor/ataxia syndrome (FXTAS), a late onset neurodegenerative disorder characterized by cerebellar gait ataxia, intentional tremor, neuropathy, parkinsonism, cognitive decline, and psychological disorders, such as anxiety and depression. In addition, brain atrophy, white matter disease, and hyperintensities of the middle cerebellar peduncles can also be present. The neuropathological distinct feature of FXTAS is represented by the presence of eosinophilic intranuclear inclusions in neurons and astrocytes throughout the brain and in other tissues. In this chapter, protocols for available diagnostic tools, in both humans and mice, the clinical features and the basic molecular mechanisms leading to FXTAS and the animal models proposed to study this disorder are discussed.