DRD3 and DAT1 genes in schizophrenia: A pharmacogenetic association study

Objectives: To investigate the role of DRD3 and DAT1 genes in schizophrenia or in modulating its phenotype. Methods: a Ser9Gly polymorphism in the DRD3 and a VNTR polymorphism in the DAT1 genes were examined in two groups of schizophrenic patients, one of excellent neu-roleptic responders (N = 42) and one of non-responders (N = 64), and in a group of healthy volunteers (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 these two genes. Results: No significant differences in the allelic distribution of the DRD3 and DAT1 polymorphisms were detected between patients and controls. A trend toward an excess of DRD3 genotype 2/2 was observed in neuroleptic non-responder schizophrenic patients compared to controls (2 = 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.