Association between a polymorphism in the promoter region of the dopamine D2 receptor gene and schizophrenia in Japanese subjects: replication and evaluation for antipsychotic-related features.

Abstract

To replicate a previously found negative association between the Del allele of the -141C Ins/Del polymorphism in the 5'-promoter region of the dopamine D2 receptor gene (DRD2) and schizophrenia in Japanese subjects and to examine whether this polymorphism is related to the features of antipsychotic drug treatment, we genotyped 94 control subjects and 234 schizophrenic patients. The schizophrenic patients had a significantly lower frequency of the Del allele (p < 0.05). We found a non-significant trend towards a higher frequency of the Del allele in schizophrenic patients susceptible to neuroleptic-induced extrapyramidal symptoms. The daily dosage of haloperidol, the steady-state concentration of serum haloperidol per daily dosage, and the recent 1-yr cumulative neuroleptic dosage were lower in patients with the Del/Del genotype than in the other patients. These findings support the view that the polymorphism is associated with schizophrenia in Japanese subjects and provide hints for further attempts to establish the relationship between this polymorphism and the features of antipsychotic drug treatment.