Association between polymorphisms of cytokine genes and endometriosis: A comprehensive systematic review and meta-analysis

Introduction: There is abundant evidence to suggest that cytokines play a part in the mechanisms responsible for the formation of endometrium heterotopy. Cytokine synthesis is not only determined by the body's immuno-logical reactivity but also by polymorphisms in the immune regulatory genes. The study of these polymorphisms in the immune regulatory genes offers up new possibilities in terms of prognosticating the risk of endometriosis and susceptibility to its treatment. The purpose of this comprehensive systematic review and meta-analysis was to investigate whether or not cytokine gene polymorphisms were linked to an increased chance of endometriosis. Methods: By searching MEDLINE, Scopus, and Web of Science databases, the relevant studies were identified. The odds ratio (OR) with 95% confidence interval (CI) was used to assess the association between TNF-& alpha;/IL-10/IL-6/ TGF-& beta;/IFN-& gamma;/IL-1 & beta; gene polymorphisms and endometriosis risk.Results: A total of 5128 cases and 5334 controls in 32 eligible studies were included in the meta-analysis. Overall, results indicated the negative association between the cytokine gene polymorphisms and endometriosis in the dominant model of TNF-& alpha; (rs1799964): [OR] = 0.64, [CI]: 0.46-0.89) and a positive association in IFN-& gamma; a13 allele: OR= 1.45, [CI]: 1.07-1.98; and IL-10 (rs1800872): [OR]= 1.60, [CI]: 1.21-2.12).Conclusion: The present study suggests that IL-10 (rs1800872) and IFN-& gamma; a13 allele may be a risk factors for endometriosis. Also, TNF-& alpha; (rs1799964) is associated with decreased susceptibility to endometriosis.