title: D2 receptor genetic variation and clinical response to antipsychotic drug treatment: a meta-analysis.
abstract: OBJECTIVE
  Several lines of evidence suggest that antipsychotic drug efficacy is mediated by dopamine type 2 (D(2)) receptor blockade. Therefore, it seems plausible that variation in the DRD(2) gene is associated with clinical response to antipsychotic drug treatment. The authors conducted the first meta-analysis to examine the relationship between DRD2 polymorphisms and antipsychotic drug response.
  
  
  METHODS
  A MEDLINE search of articles available up to December 31, 2008, yielded 18 prospective studies examining DRD2 gene variation and antipsychotic response in schizophrenia patients; of which, 10 independent studies met criteria for inclusion. Clinical response to antipsychotic treatment was defined as a 50% reduction of either the Brief Psychiatric Rating Scale total score or Positive and Negative Syndrome Scale total score at approximately 8 weeks of follow-up evaluation. Odds ratio was the primary effect-size measure and computed for each polymorphism in each study. Sufficient data were available for two DRD2 polymorphisms: -141C Ins/Del and Taq1A.
  
  
  RESULTS
  Six studies reported results for the -141C Ins/Del polymorphism (total sample size: N=687). The Del allele carrier was significantly associated with poorer antipsychotic drug response relative to the Ins/Ins genotype. Eight studies assessed the Taq1A polymorphism and antipsychotic response (total sample size: N=748). There was no significant difference in the response rate among A1 allele carriers relative to individuals with the A2/A2 genotype or A2 allele carriers relative to individuals with the A1/A1 genotype.
  
  
  CONCLUSIONS
  The DRD2 genetic variation is associated with clinical response to antipsychotic drug treatment. These data may provide proof-of-principle for pharmacogenetic studies in schizophrenia.
authors.affiliation: Division of Psychiatry Research, Department of Psychiatry, The Zucker Hillside Hospital, 75-59 263rd St., Glen Oaks, NY 11004, USA. jzhang1@nshs.edu
authors.forename: Jian-Ping
authors.initials: JP
authors.lastname: Zhang
authors.forename: Todd
authors.initials: T
authors.lastname: Lencz
authors.forename: Anil K
authors.initials: AK
authors.lastname: Malhotra
mesh_terms: D000483:Alleles; D014150:Antipsychotic Agents / Q000627:therapeutic use*; D005838:Genotype; D006801:Humans; D011110:Polymorphism, Genetic / Q000235:genetics; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011569:Psychiatric Status Rating Scales; D017448:Receptors, Dopamine D2 / Q000235:genetics*; D012559:Schizophrenia / Q000188:drug therapy / Q000235:genetics*; D016896:Treatment Outcome
chemical_list: D014150:Antipsychotic Agents; D017448:Receptors, Dopamine D2