Two gene variants appeared to be significant after adding them to the clinical regression models: (1) Ser9Gly DRD3 polymorphism was associated with severe TD (odds ratio for patients with 1 mutant allele when compared with individuals with 2 wild types was 2.5, 95% confidence interval 1.1-5.6, whereas the odds ratio for patients with 2 mutant alleles when compared with individuals with 1 mutant was 2.8, 95% confidence interval 1.0-7.4), and (2) GSTM1 absence was associated with TD (odds ratio 1.7, 95% confidence interval 1.2-2.4) particularly in white women.
We suggest that the DRD3 Ser9Gly polymorphism may be a contributing factor to the performance of eye movements used as a phenotypic marker of schizophrenia.
Thus, a number of studies have focused on the association of dopamine system gene polymorphisms and TD, with the most consistent findings being an association between TD and the Ser9Gly polymorphism of the DRD3 gene and the TaqIA site 3' of the DRD2 gene.
In this study, we examined the association between the DRD3 ser9gly and BDNF val66met genetic polymorphisms and TD occurrence in 216 schizophrenic patients (TD/non-TD = 102/114).
Search for these determinants has led to a few consensus associations of CYP2D6 *10, CYP1A2*1F, DRD2 Taq1A (rs1800497), DRD3 Ser9Gly (rs6280) and MnSOD Ala9Val (rs4880) variants with TD.
As recent observations indicate the dopamine D(3) receptor (DRD3) to modulate both therapeutic action of levodopa and dyskinesia, we reappraised the impact of the DRD3 Ser9Gly polymorphism on development of motor complications in a large scale association study based on the gene bank of the German Competence Network on Parkinson's disease.
Chinese Han patients with schizophrenia were assessed for abnormal involuntary movements, and subgroups of 42 patients with persistent tardive dyskinesia and 59 consistently without dyskinesias were assessed for the DRD3 ser9gly and the MnSOD ala-9val polymorphisms.
Remarkably, alleles of <i>COMT</i> rs165774 (G), <i>DRD2</i> rs6277 (T), and <i>DRD3</i> rs6280 (C) were associated with raised predisposition to schizophrenia (all <i>P</i><0.001).
The meta-analysis comprising 1291 East Asian subjects also showed no association between the polymorphism and TD; the Mantel-Haenszel pooled OR for TD among carriers of the DRD3 Ser9Gly of the eight Asian studies was 0.94 (95% CI: 0.78-1.12).
In our Japanese case-control sample (43 with TD/157 without TD), we found no association between the DRD3 Ser9Gly polymorphism in schizophrenia and TD (genotype: p=0.92; allele: p=1.00).
In a meta-analysis of all case-control studies comprising 8761 subjects the association between DRD3 Ser9Gly homozygosity and schizophrenia ( =4.96, degree of freedom=1, p <0.05, odds ratio=1.10, 95% confidence interval=1.01-1.20) persisted.
In this study, the authors investigated the relationship between the Ser9Gly (SG) polymorphism of the dopamine D3 receptor (DRD3) and striatal habit learning in healthy controls and patients with schizophrenia.