Dopamine D4 receptor (DRD4) gene polymorphism in the first psychotic episode

Background. Dopamine D4 receptor (DRD4) has shown some interesting properti es at genetic and possibly functional levels. It has been suggested that so me molecular variants een of the DRD4 gene (e.g,, four and seven alleles) c ould be implicated in the pathogenesis of psychotic disorders. Additionally , the VNTR polymorphism could be implicated in part of the response to trea tment with neuroleptics. This study tested the possible association between the 48-bp tandem repeats in exon 3 of the DRD4 gene and patients experienc ing their first psychotic episode. Methods. Patients with a first psychotic episode (FPE, n = 37) were diagnos ed and compared with a matched control group (n = 37). The FPE group was su bdivided into two categories: those with nonaffective and those with affect ive psychoses. The variable number of tandem repeats (VNTR) region of the D RD4 gene was amplified by PCR procedures. Chi-square statistics and appropr iate corrections and adjustments were used for data analysis. Results. A significantly lower frequency of the four repeat (4-R) carriers in the FPE group was observed. This association was sustained mainly by the affective psychotic group (chi (2) = 9.99 df = 2, p = 0.0073). Conclusions. Although these results require testing with stringent methods, it is suggested that the DRD4-4R allele may confer some protection against psychosis, mainly of the affective subtype. (C) 2001 IMSS. Published by El sevier Science Inc.