title: Association between DRD2/ANKK1 TaqIA Polymorphism and Susceptibility with Tourette Syndrome: A Meta-Analysis.
abstract: BACKGROUND
  Genetic factors are important in the pathogenesis of Tourette syndrome (TS). Notably, Dopamine receptor D2 (DRD2) gene has been suggested as a possible candidate gene for this disorder. Several studies have demonstrated that DRD2/ANKK1 TaqIA polymorphism is associated with an increased risk of developing TS. However, past results remain conflicting. We addressed this controversy by performing a meta-analysis of the relationship between DRD2/ANKK1 TaqIA polymorphism and TS.
  
  
  METHODS
  Literature was searched in multiple databases including PUBMED, COCHRANE and WEB OF SCIENCE up to July 2014. The number of the genotypes for DRD2/ANKK1 TaqIA in the TS and control subjects was extracted and statistical analysis was performed using Review Manager 5.0.16 and Stata 12.0 software. Summary odds ratios (ORs) and 95% confidence intervals (95%CIs) were utilized to calculate the risk of TS with DRD2/ANKK1 TaqIA. Stratified analysis based on ethnicity was also conducted.
  
  
  RESULTS
  523 patients with TS, 564 controls and 87 probands plus 152 relatives from five published studies were finally involved in this meta-analysis. Combined analysis revealed that the overall ORs for the DRD2/ANKK1 TaqIA A1 allele were 1.69 (95%CIs = 1.42-2.00) in the fixed-effect model and 1.66 (95%CIs = 1.33-2.08) in the random-effects model. Stratification by ethnicity indicated the TaqIA A1 allele was significantly associated with TS in Caucasians (fixed-effect model: OR=1.75, 95%CI = 1.43-2.16; random-effect model: OR=1.69, 95%CI = 1.25-2.28) and in Asians (OR=1.54, 95%CI = 1.12-2.10). Meta-analysis of the A1A1 vs. A2A2 (homozygous model), A1A2 vs. A2A2 (heterozygous model) and A1A1+A1A2 vs. A2A2 (dominant model) of this polymorphism revealed a significant association with TS in overall populations and Caucasians.
  
  
  CONCLUSIONS
  This meta-analysis suggested that the DRD2/ANKK1 TaqIA polymorphism might contribute to TS susceptibility, especially in Caucasian population. However, further investigation with a larger number of worldwide studies should be conducted to verify the association.
authors.affiliation: Department of Genetics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Center for Translational Neuromedicine and the Department of Neurology, University of Rochester Medical Center, Rochester, New York, United States of America.
authors.forename: Aihua
authors.initials: A
authors.lastname: Yuan
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Su
authors.affiliation: Department of Genetics, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Shunying
authors.initials: S
authors.lastname: Yu
authors.affiliation: Shanghai Key Laboratory of Psychotic Disorders, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Chunbo
authors.initials: C
authors.lastname: Li
authors.affiliation: Bio-X Center, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Yu
authors.affiliation: Department of Medical Psychology, Shanghai General Hospital, Shanghai Jiao Tong University, Shanghai, China; Department of Child & Adolescent Psychiatry, Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Sun
mesh_terms: D000483:Alleles; D044466:Asian People / Q000235:genetics; D016022:Case-Control Studies; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D005838:Genotype; D006801:Humans; D011110:Polymorphism, Genetic / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D012306:Risk; D005879:Tourette Syndrome / Q000209:etiology / Q000235:genetics*; D044465:White People / Q000235:genetics
chemical_list: C581293:DRD2 protein, human; D017448:Receptors, Dopamine D2; C489948:ANKK1 protein, human; D017346:Protein Serine-Threonine Kinases