The cognitive neuropsychological phenotype of carriers of the FMR1 premutation

• Type of Material: Article
• Authors: Jim Grigsby, University of Colorado Denver; Kim Cornish, Monash University; Darren Hocking, La Trobe University; Claudine Kraan, Monash University; John M Olichney, University of California, Davis; Susan M Rivera, University of California, Davis; Andrea Schneider, University of California, Davis; Stephanie Sherman, Emory University; Jun Yi, University of California, Davis; Jin-Chen Yang, University of California, Davis
• Language: English
• Date: 2014-07-30
• Publisher: BioMed Central
• Publication Version: Final Published Version
• Copyright Statement: © 2014 Grigsby et al.; licensee BioMed Central Ltd.
• License: Creative Commons Attribution 2.5 Generic
• Final Published Version (URL): http://dx.doi.org/10.1186/1866-1955-6-28
• Title of Journal or Parent Work: Journal of Neurodevelopmental Disorders
• ISSN: 1866-1947
• Volume: 6
• Issue: 1
• Start Page: 28
• End Page: 28
• Keywords: Executive function; Cognition disorders; FMR1; Fragile X premutation; Fragile X; Fragile X-associated tremor/ataxia syndrome; FXTAS
• Research Categories: Health Sciences, General; Biology, Genetics; Biology, Neuroscience

Abstract

The fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder affecting a subset of carriers of the FMR1 (fragile X mental retardation 1) premutation. Penetrance and expression appear to be significantly higher in males than females. Although the most obvious aspect of the phenotype is the movement disorder that gives FXTAS its name, the disorder is also accompanied by progressive cognitive impairment. In this review, we address the cognitive neuropsychological and neurophysiological phenotype for males and females with FXTAS, and for male and female unaffected carriers. Despite differences in penetrance and expression, the cognitive features of the disorder appear similar for both genders, with impairment of executive functioning, working memory, and information processing the most prominent. Deficits in these functional systems may be largely responsible for impairment on other measures, including tests of general intelligence and declarative learning. FXTAS is to a large extent a white matter disease, and the cognitive phenotypes observed are consistent with what some have described as white matter dementia, in contrast to the impaired cortical functioning more characteristic of Alzheimer's disease and related disorders. Although some degree of impaired executive functioning appears to be ubiquitous among persons with FXTAS, the data suggest that only a subset of unaffected carriers of the premutation - both female and male - demonstrate such deficits, which typically are mild. The best-studied phenotype is that of males with FXTAS. The manifestations of cognitive impairment among asymptomatic male carriers, and among women with and without FXTAS, are less well understood, but have come under increased scrutiny.