Psychopharmacology

, Volume 181, Issue 1, pp 179–187

Association study of 12 polymorphisms spanning the dopamine D2 receptor gene and clozapine treatment response in two treatment refractory/intolerant populations

  • Rudi Hwang
  • Takahiro Shinkai
  • Vincenzo De Luca
  • Daniel J. Müller
  • Xingqun Ni
  • Fabio Macciardi
  • Steven Potkin
  • Jeffrey A. Lieberman
  • Herbert Y. Meltzer
  • James L. Kennedy
Original Investigation

DOI: 10.1007/s00213-005-2223-5

Cite this article as:
Hwang, R., Shinkai, T., De Luca, V. et al. Psychopharmacology (2005) 181: 179. doi:10.1007/s00213-005-2223-5

Abstract

Rationale

Dopamine D2 receptor blockade is the major basis for the antipsychotic action of typical antipsychotic drugs (AP) and a necessary but not sufficient basis for the antipsychotic action of atypical APs such as clozapine and other multireceptor antagonists which rely, in part, upon 5-HT2A antagonism. Genetic factors affecting the density and/or function of D2 receptors may therefore affect AP response.

Objectives

This exploratory study investigates the effect of 12 single nucleotide polymorphisms (SNPs) spanning the entire dopamine D2 gene on clozapine response in two distinct schizophrenic populations (Caucasian and African–American) refractory or intolerant to conventional APs.

Methods

This study included 183 Caucasian and 49 African–American DSM-III-R or DSM-IV schizophrenics. Genotyping was determined by 5′-exonuclease fluorescence assays. Within each population genotype, allele, allele +/−, and haplotype frequencies were compared between responders and non-responders by X2 tests. Linkage disequilibrium analysis was also performed.

Results

In the Caucasian sample, no significant associations were found for individual SNP tests; however, two haplotypes were identified as having significant protective effects on treatment outcome. In the African–American sample, individual SNP tests identified the Taq1A, Taq1B, and rs1125394 markers as being predictive of clozapine response. Haplotype analyses identified four protective haplotypes containing these SNPs. In addition, no association between the −141C Ins/Del site and clozapine response was found in either population.

Conclusions

Interindividual variability in clozapine response among treatment refractory/intolerant patients is still not fully understood and likely involves multiple factors. This exploratory analysis suggests that the D2 receptor gene may be one such factor.

Keywords

Clozapine Antipsychotics Response Dopamine D2 Association Haplotype Pharmacogenetics Gene Receptor 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Rudi Hwang
    • 1
  • Takahiro Shinkai
    • 2
  • Vincenzo De Luca
    • 1
  • Daniel J. Müller
    • 6
  • Xingqun Ni
    • 1
  • Fabio Macciardi
    • 1
  • Steven Potkin
    • 3
  • Jeffrey A. Lieberman
    • 4
  • Herbert Y. Meltzer
    • 5
  • James L. Kennedy
    • 1
  1. 1.Neurogenetics Section, Center for Addiction and Mental HealthUniversity of TorontoTorontoCanada
  2. 2.Department of PsychiatryUniversity of Occupational and Environmental HealthKitakyushuJapan
  3. 3.Brain Imaging CenterUniversity of CaliforniaIrvineUSA
  4. 4.University of North Carolina Medical SchoolChapel HillUSA
  5. 5.Psychiatric HospitalVanderbilt UniversityNashvilleUSA
  6. 6.Departement of PsychiatryCharité University Medicine BerlinBerlinGermany