Clinical correlates of DRD4 genotypes in patients with schizophrenia

The association between allele frequencies and genotypes of DRD4 and symptom dimensions in schizophrenic patients was studied. The sample includes 108 patients, 71 males and 37 females, with the diagnosis of schizophrenia (DSM-III-R). Two factor structure (Factor 1 labeled "paranoid", Factor 2 non-paranoid) was obtained as shown by Azevedo et al (see companion Poster). All the patients were assessed using the DIGS, and the OPCRIT checklist was completed on a lifetime basis. Genomic DNA was extracted from blood cells by standard methods employing saturated sodium chloride solution. The polymerase chain reaction was carried out in a programmable heat block using Taq polymerase. The 48 bp repeat was detected by PCR. No significant associations were found between each factor and alleles 2, 4, 7, and "others" (3+5+6). Statistically significant associations were found between Factor 1 and the genotype 4,7 (p=.041) and with heterozygosity as compared with homozygosity (p=.019). This study suggests that the genotype (4,7) and heterozygosity of DRD4 alleles may constitute liability factors for development of specific dimensions of symptomatology (delusions and hallucinations) in patients with schizophrenia.