Fragile X gene expansions are not associated with dementia

The purpose of this study was to determine the frequency of fragile X mental retardation 1 (FMR1) premutation size expansions in individuals with Alzheimer's disease (AD) and other cognitive disorders compared with control subjects. FMR1 genetic screening was completed in patients being seen in a neurobehavioral or AD clinics. Appropriate controls were also collected. A second cohort was a community based, autopsy confirmed, sample of individuals with normal cognitive function, mild cognitive impairment, or AD. There was not an increased frequency of FMR1 expansions in individuals with cognitive disorders, including AD, compared with control subjects.