title: The interaction between BDNF and DRD2 in bipolar II disorder but not in bipolar I disorder.
abstract: Bipolar I (BP-I) and bipolar II (BP-II) disorders are the two most common subtypes of bipolar disorder. However, most studies have not differentiated bipolar disorder into BP-I and BP-II groups, for which the underlying etiology differentiating these two subtypes remains unclear. The genetic association between both subtypes is essential for improving our understanding. The dopamine D2 receptor/ankyrin repeat and kinase domain containing 1 (DRD2/ANKK1), one of the dopaminergic pathways, as well as the brain-derived neurotrophic factor (BDNF) gene, were reported as candidate genes in the etiology of bipolar disorder. Therefore, we examined the contribution of the BDNF and DRD2/ANKK1 genes and their interaction to the differentiation of BP-I and BP-II. Seven hundred ninety-two participants were recruited: 208 with BP-I, 329 with BP-II, and 255 healthy controls. The genotypes of the BDNF and DRD2/ANKK1 Taq1A polymorphisms were determined using polymerase chain reactions plus restriction fragment length polymorphism analysis. A significant main effect for the Val/Val genotype of the BDNF Val66Met polymorphism predicted BP-II patients. The significant interaction effect for the Val/Val genotype of the BDNF Val66Met polymorphism and A1/A2 genotype of DRD2/ANKK1 Taq1A polymorphism was found only in BP-II patients. We provide initial evidence that the BDNF Val66Me and DRD2/ANKK1 Taq1A polymorphisms interact only in BP-II disorder and that BP-I and BP-II are genetically distinct.
authors.affiliation: Department of Medicine, National Cheng Kung University Hospital, Tainan, Taiwan.
authors.forename: Chih-Chun
authors.initials: CC
authors.lastname: Huang
authors.forename: Yun-Hsuan
authors.initials: YH
authors.lastname: Chang
authors.forename: Sheng-Yu
authors.initials: SY
authors.lastname: Lee
authors.forename: Shiou-Lan
authors.initials: SL
authors.lastname: Chen
authors.forename: Shih-Heng
authors.initials: SH
authors.lastname: Chen
authors.forename: Chun-Hsien
authors.initials: CH
authors.lastname: Chu
authors.forename: San-Yuan
authors.initials: SY
authors.lastname: Huang
authors.forename: Nian-Sheng
authors.initials: NS
authors.lastname: Tzeng
authors.forename: I Hui
authors.initials: IH
authors.lastname: Lee
authors.forename: Tzung Lieh
authors.initials: TL
authors.lastname: Yeh
authors.forename: Yen Kuang
authors.initials: YK
authors.lastname: Yang
authors.forename: Ru-Band
authors.initials: RB
authors.lastname: Lu
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000145:classification* / Q000235:genetics*; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics*; D016022:Case-Control Studies; D004843:Epistasis, Genetic; D005260:Female; D005787:Gene Frequency / Q000235:genetics; D020022:Genetic Predisposition to Disease; D006801:Humans; D016015:Logistic Models; D008297:Male; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D017448:Receptors, Dopamine D2 / Q000235:genetics*
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D017448:Receptors, Dopamine D2