Gene-disease association study of tumor necrosis factor-alpha G-308A gene polymorphism with risk of major depressive disorder: A systematic review and meta-analysis

Introduction The single nucleotide polymorphism (SNP) of the tumor necrosis factor-alpha (TNF-alpha) G-308A gene is the most studied regarding susceptibility to major depressive disorder (MDD). However, results have been controversial perhaps due to the heterogeneous genetic backgrounds influenced by race as well as subtypes of depression. Methods and materials A systematic MEDLINE search was performed to retrieve all published studies that identified the connection between the TNF-alpha G-308A gene polymorphism and the risk of MDD. Results There was no statistical difference between the allele frequencies or genotypes of TNF-alpha G-308A gene and the depressive patients or healthy subjects in the five models tested. Further, subgroup analyses showed that the TNF-alpha G-308A gene polymorphism also did not confer susceptibility to poststroke, late-life, maternal, or major depression. Publication bias analysis showed p values were more than .05, suggesting that the 9 articles included in the current analysis had no publication bias. Conclusion Neither the allele frequencies nor genotypes of TNF-alpha G-308A gene could be served as an independent risk factor of depression.