title: Genetic variation of brain-derived neurotrophic factor (BDNF) in bipolar disorder: case-control study of over 3000 individuals from the UK.
abstract: BACKGROUND
  Brain-derived neurotrophic factor (BDNF) influences neuronal survival, proliferation and plasticity. Three family-based studies have shown association of the common Valine (Val) allele of the Val66Met polymorphism of the BDNF gene with susceptibility to bipolar disorder.
  
  
  OBJECTIVE
  To replicate this finding.
  
  
  METHODS
  We genotyped the Val66Met polymorphism in our UK White bipolar case-control sample (n=3062).
  
  
  RESULTS
  We found no overall evidence of allele or genotype association. However, we found association with disease status in the subset of 131 individuals that had experienced rapid cycling at some time (P=0.004). We found a similar association on re-analysis of our previously reported family-based association sample (P < 0.03, one-tailed test).
  
  
  CONCLUSIONS
  Variation at the Val66Met polymorphism of BDNF does not play a major role in influencing susceptibility to bipolar disorder as a whole, but is associated with susceptibility to the rapid-cycling subset of the disorder.
authors.affiliation: Department of Psychological Medicine, Henry Wellcome Building, Wales College of Medicine, Cardiff University, Heath Park, Cardiff CF4 4XN, Wales, UK.
authors.forename: Elaine K
authors.initials: EK
authors.lastname: Green
authors.forename: Rachel
authors.initials: R
authors.lastname: Raybould
authors.forename: Stuart
authors.initials: S
authors.lastname: Macgregor
authors.forename: Sally
authors.initials: S
authors.lastname: Hyde
authors.forename: Allan H
authors.initials: AH
authors.lastname: Young
authors.forename: Michael C
authors.initials: MC
authors.lastname: O'Donovan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Owen
authors.forename: George
authors.initials: G
authors.lastname: Kirov
authors.forename: Lisa
authors.initials: L
authors.lastname: Jones
authors.forename: Ian
authors.initials: I
authors.lastname: Jones
authors.forename: Nick
authors.initials: N
authors.lastname: Craddock
mesh_terms: D001714:Bipolar Disorder / Q000235:genetics*; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D016022:Case-Control Studies; D004739:England; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D014633:Valine / Q000235:genetics*; D014852:Wales
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D014633:Valine