Abstract: Objective · To explore the relationship between aggressive behavior, dopamine receptor D4 (DRD4) exon Ⅲ 48 bp variable number tandem repeat (VNTR) and personality characteristics in patients with bipolar disorder. Methods · January 2015 to December 2018, 173 patients with bipolar disorder were selected Shanghai Changning Mental Health Center, Shanghai Jingan Mental Health Center, Shanghai Xuhui Mental Health Center, and Shanghai Jiading Central Hospital. According to the score of Modified Overt Aggression scale (MOAS), 173 patients were divided into aggressive behavior group (research group) and non-aggressive behavior group (control group). General survey and the temperament and personality questionnaire (Temperature and Character Inventory, TCI) were carried out, respectively. The polymorphism of DRD4 gene were genotypedthe polymerase chain reaction-restriction fragment length polymorphism method. Genetic equilibrium test of genotype Hardy-Weinberg and the difference of genotype frequency between the two groups were analyzedusing SHEsis software. The relationship between aggression behavior and DRD4 gene polymorphism and personality traits in bipolar disorder patients was analyzedχ2 test and t test. Results · There was no significant difference in the general data between research group and control group (P>0.05). Six alleles and nine genotypes of DRD4 exon Ⅲ 48 bp VNTR were detected. The most common alleles in the two groups were four repeat alleles. There were statistical differences in the frequency distribution of genotypes and alleles of DRD4 exon Ⅲ 48 bp VNTR between the two groups (P0.040, P0.018). The scores of novelty seeking and harm avoidance in the research group were higher than those in the control group (P0.026, P0.000), while the scores of cooperativeness and self-directedness were lower than those in the control group (both P0.000). Patients with long repeat alleles had significantly higher scores in novelty seeking and harm avoidance, and lower scores in cooperativeness, compared with patients with short repeat alleles (P0.000, P0.006, P0.038). Conclusion · Aggressive behavior in patients with bipolar disorder may be associated with DRD4 exon Ⅲ 48 bp VNTR. In bipolar disorder, patients with aggressive behavior have unique personality characteristics in impulsiving, novelty-seeking, exploring, being afraid of uncertainty, revengeful, behaving himself and so on. Patients with long repeat alleles have more significant personality abnormalities.

Key words: bipolar disorder, aggressive behavior, dopamine receptor D4 (DRD4), personality characteristics, association analysis