title: Fragile X premutation carriers: A systematic review of neuroimaging findings.
abstract: BACKGROUND
  Expansion of the CGG repeat region of the FMR1 gene from less than 45 repeats to between 55 and 200 repeats is known as the fragile X premutation. Carriers of the fragile X premutation may develop a neurodegenerative disease called fragile X-associated tremor/ataxia syndrome (FXTAS). Recent evidence suggests that premutation carriers experience other psychiatric difficulties throughout their lifespan.
  
  
  METHODS
  Medline, EMBASE and PsychINFO were searched for all appropriate English language studies published between January 1990 and December 2013. 419 potentially relevant articles were identified and screened. 19 articles were included in the analysis.
  
  
  RESULTS
  We discuss key structural magnetic resonance imaging (MRI) findings such as the MCP sign and white matter atrophy. Additionally, we discuss how functional MRI results have progressed our knowledge of how FXTAS may manifest, including reduced brain activation during social and memory tasks in multiple regions.
  
  
  CONCLUSIONS
  This systematic review may have been limited by the search for articles on just 3 scientific databases. Differing techniques and methods of analyses between research groups and primary research articles may have caused differences in results between studies.
  
  
  CONCLUSIONS
  Current MRI studies into the fragile X premutation have been important in the diagnosis of FXTAS and identifying potential pathophysiological mechanisms. Associations with blood based measures have also demonstrated that neurodevelopmental and neurodegenerative aspects of the fragile X premutation could be functionally and pathologically separate. Larger longitudinal studies will be required to investigate these conclusions.
authors.affiliation: Patrick Wild Centre, Division of Psychiatry, School of Molecular and Clinical Medicine, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh EH10 5HF, UK. Electronic address: s0935170@sms.ed.ac.uk.
authors.forename: Stephanie S G
authors.initials: SS
authors.lastname: Brown
authors.affiliation: Patrick Wild Centre, Division of Psychiatry, School of Molecular and Clinical Medicine, University of Edinburgh, Royal Edinburgh Hospital, Edinburgh EH10 5HF, UK. Electronic address: andrew.stanfield@ed.ac.uk.
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Stanfield
mesh_terms: D001259:Ataxia / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D001284:Atrophy / Q000473:pathology; D051860:Fragile X Messenger Ribonucleoprotein 1 / Q000235:genetics*; D005600:Fragile X Syndrome / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009154:Mutation; D059906:Neuroimaging / Q000379:methods; D014202:Tremor / Q000235:genetics / Q000473:pathology* / Q000503:physiopathology*; D019680:Trinucleotide Repeat Expansion / Q000235:genetics
chemical_list: D051860:Fragile X Messenger Ribonucleoprotein 1; C497683:FMR1 protein, human
keywords: FXTAS; Fragile X premutation; Fragile X syndrome; MRI; Neuroimaging; Premutation carriers