title: BDNF Val66Met polymorphism and plasma levels in Chinese Han population with obsessive-compulsive disorder and generalized anxiety disorder.
abstract: BACKGROUND
  Anxiety disorders are a category of mental disorders characterized by feelings of anxiety and fear, which include generalized anxiety disorder (GAD). Obsessive-Compulsive Disorder (OCD) used to be categorized as anxiety disorder in DSM-IV. However OCD was no longer included in anxiety disorders and came into its own category titled as Obsessive-Compulsive and Related Disorders (OCRD) in DSM-5. It will be interesting to explore is there any different biological characteristics between OCD and anxiety disorders. Brain-derived neurotrophic factor (BDNF) was a potential candidate gene in both OCD and GAD. The results of genetic association studies between BDNF and OCD have been inconsistent. BDNF plasma/serum levels in OCD have been found lower than those in healthy controls. However the heritable reason of the lowered BDNF levels was not well elucidated. The amount of studies about BDNF and GAD were relatively small. The aims of this study were to determine whether single nucleotide polymorphism Val66Met of BDNF was associated with OCD and GAD, to examine BDNF plasma levels in OCD and GAD, and to explore whether Val66Met variation influences BDNF plasma levels.
  
  
  METHODS
  We genotyped Val66Met variation in 148 OCD patients, 108 GAD patients and 99 healthy controls. Within the same sample, BDNF plasma levels were determined in 113 OCD patients, 102 GAD patients and 63 healthy controls.
  
  
  RESULTS
  Val66Met variation was not associated with OCD or GAD. BDNF plasma levels in OCD and GAD patients were significant lower than those in healthy controls. Val66Met variation had no influence on BDNF plasma levels. No difference was found between OCD and GAD. Results do not change no matter taking OCD and GAD as one group or separated two.
  
  
  CONCLUSIONS
  First, the sample size for genotyping was relatively small, which leaded to a low statistical power of the genetic part in this study. Second, we genotyped just one SNP in BDNF gene. Third, parts of the participants did not be assayed for BDNF plasma levels.
  
  
  CONCLUSIONS
  Our findings support the hypothesis that BDNF is involved in the pathophysiology of mental disorders, not only OCD but also GAD. OCD and GAD patients both show lower BDNF plasma levels compared to healthy controls. The BDNF plasma levels are not associated with Val66Met variation.
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Haiyin
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Zhen
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Fan
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Shunying
authors.initials: S
authors.lastname: Yu
authors.affiliation: Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China.
authors.forename: Zhiguang
authors.initials: Z
authors.lastname: Lin
authors.affiliation: Psychiatric Department of Shanghai Jiao Tong University School of Medicine, 200030 Shanghai, China. Electronic address: xiaozeping88@163.com.
authors.forename: Zeping
authors.initials: Z
authors.lastname: Xiao
mesh_terms: D000328:Adult; D001008:Anxiety Disorders / Q000097:blood / Q000235:genetics*; D044466:Asian People / Q000235:genetics*; D019208:Brain-Derived Neurotrophic Factor / Q000097:blood / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D009771:Obsessive-Compulsive Disorder / Q000097:blood / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D055815:Young Adult
chemical_list: D019208:Brain-Derived Neurotrophic Factor; C579455:BDNF protein, human
keywords: Brain-derived neurotrophic factor; Generalized anxiety disorder; Obsessive-compulsive disorder; Plasma; Val66Met