The association between dopamine D4 receptor exon III polymorphism and intensity of PTSD symptoms among flood survivors.

Thanks to the development of molecular genetics methods it is now possible to look for the genes which may contribute to posttraumatic stress disorder (PTSD). Polymorphism located in exon III of dopamine receptor type 4 (DRD4) gene was related to maladaptive stress responses as well as temperament traits related to PTSD. This study analyzed the association between the variable number tandem repeat (VNTR) DRD4 exon III polymorphism and intensity of PTSD symptoms in 107 (57 women and 50 men) survivors of a flood aged 14-62. Intensity of PTSD symptoms was measured using PTSD-F and PTSD-C questionnaires. Multivariate analysis of covariance (MANCOVA) was conducted to test the main and interactive effects of genotype and level of trauma exposure. Participants with at least one copy of the DRD4 long allele (seven or eight repetitions) had more intense PTSD symptoms on the Avoidance/Numbing scale (Cohen's f = .22) and the Total Scale (Cohen's f = .2) of the PTSD-F than participants who did not have these alleles in genotype. The results must be treated with caution, however, due to methodological restrictions and they need to be replicated on a larger sample.