Association of the SLC6A4, SLC6A3, COMT and BDNF Gene Polymorphisms with Suicidal Behavior: A Case Control Study

BackgroundSuicide causes about 1 million deaths per year. Familial transmission of suicide, as well as the involvement of serotonin and dopamine systems in suicidal behavior, was confirmed by previous studies. We investigated an effect of 11 polymorphisms of 9 genes related to dopamine and serotonin transmission (SLC6A4, HTR1A, HTR2A, HTR1B, SLC6A3, DRD4, DRD2, COMT, and BDNF) on the risk of suicide. MethodsThe study was performed on 100 psychiatric clinic patients with repeated suicide attempts. Genomic DNA was obtained from venous blood. Genotyping was performed using locus-specific PCR. Statistical analysis was carried out using a Pearson Chi-squared test, ORs, with the corresponding 95% CIs and one-way ANOVA.ResultsAssociation of the SLC6A3 40–45 bp VNTR and SLC6A4 rs25531 loci with suicidal behavior was tested for the first time. We have shown that a short allele of SLC6A3 40–45 bp VNTR locus might increase the risk of suicidal attempts (p = 0.009). Contrary to previous research, we have found that the Val-allele of COMT rs4680 is associated with suicide (p = 0.028). T-allele of BDNF rs6264 and A-allele of SLC6A4 rs25531 were associated with suicidal behavior with p = 0.029 and p = 0.047, respectively. ANOVA showed the lack of association between these loci and severity of depressive symptoms, but revealed a possible effect of SLC6A4 40 bp VNTR and HTR1B loci on anxiety symptoms. ConclusionsOur results suggest that allelic variants of SLC6A3, SLC6A4, COMT and BDNF genes might be considered as risk factors for repeated suicide attempts in patients with different mental disorders. Loci SLC6A4 40 bp VNTR and HTR1B rs6296 may affect anxiety symptoms.