-141C Ins/Del polymorphism of the dopamine D2 receptor gene is associated with schizophrenia in a Spanish population

OBJECTIVE: In this study we examined the relationship between dopamine D2 receptor (DRD2) polymorphisms (TaqIA, TaqIB, -141C Ins/Del) and dopamine D3 receptor (DRD3) Ser9Gly polymorphism and the risk of schizophrenia in a Spanish population. METHODS: Two hundred and forty-three schizophrenia patients and 291 healthy controls from the general population participated in a case-control study. RESULTS: No significant differences were observed in the allele or genotype frequencies of TaqIA, TaqIB or Ser9Gly polymorphisms between the schizophrenia patients and the healthy controls. The frequency of the -141C Del allele was significantly lower in the former group (odds ratio=0.4, P=0.01). The -141C Del allele, which produces lower expression of DRD2, may protect against dopaminergic hyperactivity in schizophrenia. CONCLUSION: This study is one of the few studies of Caucasian participants that supports the results obtained in the original Japanese study, in which the -141C Ins/Del polymorphism was first described. Furthermore, our findings reinforce the hypothesis that excess dopaminergic activity leads to schizophrenia.