BACKGROUND: No association between schizophrenia and dopamine D4 receptor polymorphisms have been reported. Despite these results, it is premature to exclude the association. It has been suggested that the susceptibility to develop schizophrenia could result from variation at a number loci which may interact or co-act with each other. Therefore, we investigated a possible assoication of combinations of exon III 48bp polymorphism [D4E3] and exon I 12bp polymorphism of the DRD4 gene [D4E1] with schizophrenia. METHOD: 207 unrelated Korean schizophrenic patients and 191 healthy controls wee recruited. DRD4 genotype was established using the polymerase chain reaction. Statistical analysis consisted of chi2 tests for Hardy-Weinberg proportions and genotypic and allelic frequencies in the patients and control groups. RESULT: There were no statistically significant differences in the each polymorphisms between schizophrenics and controls. And all genotype frequencies were within Hardy-Weinberg expectations. When the combinations of the polymorphism in schizophrenia and controls were compared, however, there were significant differences at A1A2*2/4 in the distributions of the combinations of D4E1 and D4E3(p<0.01). CONCLUSION: These findings suggest that the certain combination of D4E1 and D4E3 (A1A2*2/4) has the protective role to a susceptibility for schizophrenia.
Dopamine* ; Exons ; Genotype ; Humans ; Polymerase Chain Reaction ; Receptors, Dopamine D4 ; Schizophrenia