Investigation of Serotonin Transporter Gene Promoter (5-HTTLPR) and Intron 2 (Variable Number of Tandem Repeats) Polymorphisms with Suicidal Behavior in a Turkish Population

The serotonin (5-hydroxytryptamine) transporter (5HTt) gene has been reported to be associated with suicidal behavior. In this study, we have investigated the 50 promoter region (i.e., 5HTt gene-linked polymorphic region [5-HTTLPR]) and a 17-base pair variable number of tandem repeats polymorphism in the 5HTt gene for potential association with suicidal behavior in a Turkish population. Genotypes were determined for 182 subjects of suicide (86 attempted suicide and 96 completed suicide) and 181 healthy control subjects. Our results showed that allele frequencies at individual loci were not significantly different in the two groups. This absence of altered individual locus haplotype (allele) frequency suggests the lack of a significant genetic contribution by the 5-HTTLPR or variable number of tandem repeats variations to the expression of suicidal tendencies. However, our linkage disequilibrium analyses indicated that there may be a greater risk for suicidal behavior in carriers of the S10 and L12 alleles of 5-HTTLPR.