Fragile X-Associated Tremor Ataxia/Syndrome

Approximately one-third of the male carriers of the fragile X premutation allele (CGG repeat size of 55-200 on the. FMR1 gene) are at risk of developing the neurodegenerative disorder fragile X-associated tremor/ataxia syndrome (FXTAS). This disorder is caused by a mutation in the same gene on the X chromosome as the childhood-onset neurodevelopmental disorder fragile X syndrome. FXTAS is characterized by gait ataxia, intention tremor, and brain atrophy with intranuclear inclusions found in cortical and subcortical structures. FXTAS is commonly mistaken for other movement disorders, such as atypical Parkinson's disease and multiple system atrophy.