Abstract
The dopamine D3 receptor gene is a candidate locus that may confer susceptibility to shizophrenia. I examined a Ser-9-Gly polymorphism in the D3 receptor protein for an allelic association in 78 Japanese schizophrenia patients and 90 controls. Polymerase chain reaction and digestion by the restriction enzyme Bal I were used for genotyping. There was no significant difference between the two groups in allele frequencies or genotype distribution. When the clinical variables of history of admission to a psychiatric hospital, dosage of antipsychotics, and ase of onset were examined in relation to the genotype and allele frequencies, homozygosity for the Ser-9 allele was found to be less common among patients younger at onset (≤21 year) than among those older at onset (p<0.05) . The clinical variables did not show any significant association with genotype or allele frequency. The present results suggest that the variation in the dopamine D3 receptor gene may have an effect on the age of onset in schizophrenia, although further studies with larger numbers of patients are required.
