Synaptosomal- Associated Protein 25 Gene Polymorphisms and Antisocial Personality Disorder: Association with Temperament and Psychopathy

Abstract

Objective: The molecular genetic of personality disorders has been investigated in several studies; however, the association of antisocial behaviours with synaptosomal-associated protein 25 (SNAP25) gene polymorphisms has not. This association is of interest as SNAP25 gene polymorphism has been associated with attention-deficit hyperactivity disorder and personality. Methods: We compared the distribution of Ddel and Mnll polymorphisms in 91 young male offenders and in 38 sex-matched healthy control subjects. We also investigated the association of SNAP25 gene polymorphisms with severity of psychopathy and with temperament traits: novelty seeking, harm avoidance, and reward dependence. Results: The Mnll T/T and Ddel T/T genotypes were more frequently present in male subjects with antisocial personality disorder (APD) than in sex-matched healthy control subjects. The association was stronger when the frequency of both Ddel and Mnll T/T were taken into account. In the APD group, the genotype was not significantly associated with the Psychopathy Checklist–Revised scores, measuring the severity of psychopathy. However, the APD subjects with the Mnll T/T genotype had higher novelty seeking scores; whereas, subjects with the Ddel T/T genotype had lower reward dependence scores. Again, the association between genotype and novelty seeking was stronger when both Ddel and Mnll genotypes were taken into account. Conclusion: Ddel and Mnll T/T genotypes may be a risk factor for antisocial behaviours. The association of the SNAP25 Ddel T/T and Mnll T/T genotypes with lower reward dependence and higher novelty seeking suggested that SNAP25 genotype might influence other personality disorders, as well.