Possible association between serotonin transporter gene polymorphism and violent suicidal behavior in mood disorders

Background: Genes involved in the serotonin system are major candidates in association studies of suicidal behavior. In this case–control study we investigated whether the serotonin transporter (5-HTT) gene encoding the protein responsible for the reuptake of serotonin from the synapse after its release from serotonergic neurons is a susceptibility factor for suicidal behavior. Methods: A functional polymorphism of the 5-HTT gene (a 44–base pair insertion/deletion in the 5-HTT–linked polymorphic region [5-HTTLPR]) was studied in a population of 237 consecutive patients with affective disorder (unipolar or bipolar) and 187 control subjects. Ninety-nine patients had attempted suicide at least once, of whom 26 made a violent attempt. Results: No association was found between the “s” allele of the 5-HTTLPR and suicide attempt; however, there was a significant difference in allele distributions between patients who had made violent suicide attempts and control subjects. Conclusions: A genetic variant of the 5-HTT gene may predispose individuals to violent suicidal behavior. The precise phenotype associated with the 5-HTT gene is unclear, and therefore further studies are required to replicate these findings.