Dopamine transporter polymorphisms and risperidone response in Chinese schizophrenia patients: an association study.

Risperidone is a widely used atypical antipsychotic medication and there is currently considerable interest in individual differences in patient response to it. In this study, we investigated the pharmacogenetic correlates of SLC6A3 and response to risperidone treatment in 130 Chinese schizophrenia patients. We selected six polymorphisms, including two SNPs in the 5'-regulatory regions, two SNPs in intron 1, one SNP and a variable number tandem repeat in the 3'-flanking region of SLC6A3 for this study and analyzed the differences in the reduction of Positive and Negative Syndrome Scale (PANSS) scores among the subgroups with different genotypes and diplotypes after 8 weeks of risperidone treatment. The confounding effects of nongenetic factors were estimated and the baseline symptom score was included as a covariate for adjustment. We found no significant differences in response to treatment in terms of PANSS or subscores improvements among the subgroups according to different genotypes and diplotypes. In addition, we have found no significant differences between different diplotypic groups in the plasma levels of risperidone and 9-hydroxyrisperidone. Further studies on larger groups and on the effects of longer-term risperidone treatment are needed to confirm these results.