Suicidal Behavior and the Serotonin Transporter Gene Polymorphism (5-HTTLPR) with Novel Subtypes, in Danish Schizophrenic Patients

Background: Literature reports a genetic component for suicidal behavior, especially of determinant/violent type. One of the candidates has been the polymorphism 5-HTTLPR in the serotonin promoter. Employing a between group design, we wished to test the association between suicidal behavior and serotonin-related polymorphisms. Method: 350 Danish patients with average 14 years' duration of illness and with well researched history of suicidal behavior participated. Three groups were identified: 1. without suicidal behavior, 2. with suicidal behavior of non- determinant/non-violent methods, and 3. suicidal behavior with determinant/violent methods. We used the common alleles S and L as well as the new aspect with allelic subtypes SA, SG, LA.LG to constitute 3 functional genotypes: SS, SL and LL. We also included duration of illness, age at onset and sex in our study as potential covariates. Results: We tested suicidal behavior types 2 and 3 versus type 1 for distribution differences as well as for possible trend. We did not find any statistical significant relations. Conclusions: We could not find support for a relevant relation between the polymorphisms in the serotonin promoter and suicidal behavior in our schizophrenic patient sample.