title: No association between the Val66Met polymorphism of the brain-derived neurotrophic factor gene and bipolar disorder in a Japanese population: a multicenter study.
abstract: BACKGROUND
  Two previous studies reported a significant association between a missense polymorphism (Val66Met) in the brain-derived neurotrophic factor (BDNF) gene and bipolar disorder; however, contradictory negative results have also been reported, necessitating further investigation.
  
  
  METHODS
  We organized a multicenter study of a relatively large sample of 519 patients with bipolar disorder (according to DSM-IV criteria) and 588 control subjects matched for gender, age, and ethnicity (Japanese). Genotyping was done by polymerase chain reaction-based restriction fragment length polymorphism or direct sequencing.
  
  
  RESULTS
  The genotype distributions and allele frequencies were similar among the patients and control subjects. Even if the possible relationships of the polymorphism with several clinical variables (i.e., bipolar I or II, presence of psychotic features, family history, and age of onset) were examined, no variable was related to the polymorphism.
  
  
  CONCLUSIONS
  The Val66Met polymorphism of the BDNF gene is unrelated to the development or clinical features of bipolar disorder, at least in a Japanese population.
authors.affiliation: Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1 Ogawahigashi, Kodaira, Tokyo, Japan. hkunugi@ncnp.go.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kunugi
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Iijima
authors.forename: Masahiko
authors.initials: M
authors.lastname: Tatsumi
authors.forename: Mariko
authors.initials: M
authors.lastname: Yoshida
authors.forename: Ryota
authors.initials: R
authors.lastname: Hashimoto
authors.forename: Tadafumi
authors.initials: T
authors.lastname: Kato
authors.forename: Kaoru
authors.initials: K
authors.lastname: Sakamoto
authors.forename: Takako
authors.initials: T
authors.lastname: Fukunaga
authors.forename: Toshiya
authors.initials: T
authors.lastname: Inada
authors.forename: Tatsuyo
authors.initials: T
authors.lastname: Suzuki
authors.forename: Nakao
authors.initials: N
authors.lastname: Iwata
authors.forename: Norio
authors.initials: N
authors.lastname: Ozaki
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yamada
authors.forename: Takeo
authors.initials: T
authors.lastname: Yoshikawa
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001714:Bipolar Disorder / Q000453:epidemiology / Q000235:genetics*; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D016009:Chi-Square Distribution; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008715:Methionine / Q000235:genetics*; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D012333:RNA, Messenger / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014633:Valine / Q000235:genetics*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D012333:RNA, Messenger; D008715:Methionine; D014633:Valine