Dopamine D3 receptor gene polymorphism and the psychiatric symptoms seen in first-break schizophrenic patients

To investigate the possible effect of polymorphism at the BalI site of the dopamine D3 receptor gene (DRD3) on the phenotype in human subjects, allele and genotype frequencies for this polymorphic site were examined in 113 schizophrenic patients, including six subgroups, and 48 normal controls. The schizophrenic subgroups included patients with early onset, those with a family history, and those who suffered from one of the following psychiatric symptoms at their first episode: (1) delusion and hallucination; (2) disorganization; (3) bizarre behavior; and (4) negative symptoms. No significant differences were observed in genotype, allele and homozygosity frequencies between the whole group or any subgroup of schizophrenic patients and the controls. The present results indicate that polymorphism at the BalI site of the DRD3 is unlikely to be a major contributor to any of the psychiatric parameters examined in the present population of schizophrenic subjects.