DRD2 and schizophrenia: Given that most antipsychotic drugs act as DRD2 antagonists, and although the results of meta-analyses remain inconclusive [29, 36, 95–98], about 35% of case–control studies suggest that at least one SNP in DRD2 is significantly associated with schizophrenia [99], we assumed that its biological underpinnings are complex and that the differences in clinical phenotype may, at least in part, result from polymorphisms in DRD2 gene.