DRD4 exon 3 variants associated with delusional symptomatology in major psychoses: A study on 2,011 affected subjects

We previously reported an association of DRD4 exon3 long allele variants wi th delusional symptomatology independently from diagnoses. The aim of this investigation was to study DRD4 in major psychoses and to test the associat ion in a larger sample, We studied 2,011 inpatients affected by bipolar dis order (n=811), major depressive disorder (n=635), schizophrenia (n=419), de lusional disorder (n=104), psychotic disorder not otherwise specified (n=42 ), and 601 healthy controls. a subsample of 1,264 patients were evaluated u sing the OPCRIT checklist and differences of symptomatology factor scores a mong genetic variants were assessed using one-way analysis of variance (ANO VA), DRD4 allele and genotype frequencies in bipolars, schizophrenics, delu sionals, and psychotic NOS were not significantly;v different from controls ; major depressives showed a trend toward an excess of DRD4*Short and DRD4* Short/Short variants versus controls. The ANOVA on factor scores in the who le subsample of 1,264 subjects showed a significant difference on delusion factor in allele analysis (P=0.007), and in genotype one (P=0.018), with DR D4*Long containing variants associated with severe symptomatology. The anal ysis in the replication subjects only (n=803) showed a trend in the same di rection, though not reaching the significance level. This analysis in an en larged sample suggests that DRD4*Long alleles exert a small but significant influence on the delusional symptomatologly in subjects affected by major psychoses. (C) 2001 Wiley-Liss, Inc.