DRD3 and DAT1 genes in schizophrenia: An association study

Objective: To investigate the role of the dopamine receptor 3 (DRD3) and transporter 1 (DAT1) genes in schizophrenia or in modulating its phenotype. Methods: a Ser9Gly polymorphism in codon 9 of the DRD3 and a VNTR polymorphism in the DAT1genes were examined in two groups of schizophrenic patients, one of excellent neuroleptic responders (N=42) and one of nonresponders (N=64). A group of healthy volunteers screened for major psychiatric disorders was also included (N=89). In addition, age at onset of psychotic symptoms, attention performance and family loading for schizophrenia spectrum disorders were compared between patients with different genotypes in the DRD3 and DAT1 genes. Results: No significant differences in the allelic distribution of the DRD3 and DAT1 polymorphisms were detected between schizophrenic patients and controls. A trend toward an excess of DRD3 genotype Gly/Gly was observed in neuroleptic nonresponder schizophrenic patients compared to controls (χ²=3.30, df=1, p=0.07). No significant differences in age at onset of psychotic symptoms, attention task performance or family loading for schizophrenia spectrum disorders were observed between groups with different DRD3 and DAT1 genotypes. Conclusion: These results do not support the role of either of these genes in increasing susceptibility to schizophrenia or in modulating its phenotype in the studied population. Copyright (C) 2000 Elsevier Science Ltd.