The role of COMT gene Val108/158Met polymorphism in suicidal behavior: systematic review and updated meta-analysis

Background It is accepted that there is a genetic factor that influences the risk of suicidal behavior. The catechol-O-methyltransferase (COMT) gene, especially the Val108/158Met polymorphism, has been associated with suicide; however, no conclusive outcome has been attained. Therefore, the aim of the present study was to assess the role of COMT Val108/158Met in suicidal behavior throughout an updated meta-analysis. Methods We performed an online search using PubMed and Web of Science (up to March 2017). Our systematic review included case-control studies of individuals who attempted suicide and completed suicide. We tested allelic, homozygous, heterozygous, dominant, and recessive inheritance models. The meta-analysis was performed in accordance with the statement of Preferred Reporting Items for Systematic Reviews and Meta-Analyses. Results The meta-analysis comprised 17 studies, which included 3,282 cases and 3,774 controls, and showed that when evaluating the overall population, the Val108/158Met polymorphism of COMT was not associated with suicidal behavior in any of the inheritance models; however, the subanalyses showed that this polymorphism exhibits a risk factor in males and a protective effect in females. Additionally, it conveyed a risk factor in Asian populations when using the allelic (OR 1.25; CI: 1.04-1.51) and recessive models (OR 1.32; CI: 1.03-1.68). Conclusion Our updated meta-analysis suggests a possible association between COMT Val108/158Met and suicidal behavior in Asian populations. However, in view of the small number of studies, these results should be considered exploratory. We recommend that more studies be performed with larger samples.