The effects of 5-HTTLPR/rs25531 serotonin transporter gene polymorphisms on antisocial personality disorder among criminals in a sample of the Turkish population

Abstract

Antisocial personality disorder (ASPD) is a cluster B personality disorder characterized by a disposition for criminal behaviors. It has been determined by previous studies that ASPD may have a genetic origin and the human serotonin transporter gene (SLC6A4) is one of the two serotonergic genes expected to be associated with this disorder. 5-HTT-linked polymorphic promoter region (5-HTTLPR) is a degenerate repeat polymorphic region in SLC6A4, the gene that codes for the serotonin transporter. Among many polymorphisms in SLC6A4, 5-HTTLPR an insertion/deletion (indel) polymorphism and rs25531 single nucleotide polymorphism (SNP) in the 5-HTTLPR polymorphic region contribute to the regulation of SLC6A4 expression. In this study, we aimed to reveal the relationship between frequencies of 5-HTTLPR variants and ASPD among criminals in the Turkish population. Moreover, it was also attempted to figure out the SLC6A4 gene expression level differences regarding these polymorphisms. The 5-HTTLPR/rs25531 genotypes were determined by PCR and restriction length polymorphism (RFLP) analyses and quantitative real-time-PCR was done for measuring the gene expression levels in the case and control groups. Although no significant difference was observed in the distributions of the 5-HTTLPR/rs25531 polymorphisms between the case and control groups, SLC6A4 expression level in the control group was found significantly higher than the case group (p < 0.0001). There was also no significant difference between genotypes in terms of mRNA expression levels in either the control or the case group. According to our results, ASPD in Turkish society is associated with the SLC6A4 gene expression levels, though the distributions of 5-HTTLPR polymorphisms are not different. This study sheds light on future relevant studies as the first study which is conducted in criminals with ASPD in the Turkish community.