Background: Disturbances in serotonin (5HT) transmission are the most frequently reported neurobiological substrates of suicidal behavior. Because 5HT transporter plays a central role in the regulation of 5HT synaptic function and its gene contains two functional polymorphisms (5-HTTLPR in the promoter region and VNTR in the second intron), it represents an interesting candidate for association studies in suicidal behavior.
Methods: In this study, a possible association of 5-HTTLPR and intron 2-VNTR polymorphisms of the 5HT transporter gene with suicidal behavior was investigated in a sample of 135 suicide victims and 299 healthy control subjects of Croatian/southern Slavic origin.
Results: There were no significant differences in 5-HTTLPR and intron 2-VNTR genotype- and allele- frequency distributions between suicide victims and healthy control subjects; however, a tendency toward an increase of 5-HTTLPR allele L and VNTR-allele 10 were observed in suicide group. Analysis of distribution of estimated haplotype frequencies revealed differences between suicide victims and control subjects, with an excess of haplotype L10 among suicide victims (p =.0112).
Conclusions: Our results provide modest evidence for a possible association of the 5HT transporter gene with a completed suicide. Further studies are needed to determine whether alterations in 5HTt gene expression are involved in suicidal behavior.