Association of TNF-α gene T-1031C polymorphism with endometriosis: A meta-analysis

The single nucleotide polymorphism T-1031C has shown to have an important role in the regulation and transcription efficiency of TNF-α gene. Yet, the relationship between TNF-α T-1031C gene polymorphism and the development of endometriosis (EM) still remains unclear. The aim of this meta-analysis was to summarize the effects of TNF-α T-1031C gene polymorphism and clarify their possible association with EM. A comprehensive literature search was performed using PubMed, EMBASE, Web of Science, and the Cochrane Central Register of Controlled Trials (up to August 10, 2019). A fixed- or random-effects model was employed according to the heterogeneity among studies. The log odds ratios and 95% confidence intervals (CIs) were estimated in the models of allele comparison (T vs C), homozygote comparison (TT vs CC) and (TC vs CC), dominant (TT vs TC + CC), hyperdominant (TT + CC vs TC), and recessive (TT + TC vs CC) to estimate the strength of the associations. A total of 7 case-control studies were included in this meta-analysis. Overall, significant associations between TNF-α T-1031C and EM were identified from (T vs C: log OR [95% CI] = 0.31 [-0.09, 0.71]; TT + CC vs TC: 0.27 [0.04, 0.50]; TC + CC vs TT: -0.83 [-1.19, -0.47]). On the other hand, no significant correlation was found in other gene models (TT vs TC: log OR [95% CI] = 0.89 [0.64, 1.13]; TT vs CC: 0.3 [-0.74, 1.36]; TT + TC vs CC: 0.17 [-0.81, 1.15]). In subgroup analyses by ethnicity or HWE P-value, there was a statistically significant association between TNF-α T-1031C polymorphisms and EM in the dominant model (TT vs TC + CC: log OR [95%] = -0.84 [-1.60, -0.09]) for the European population, and in hyperdominant model (TT + CC vs TC: log OR [95%] = 0.24 [0.001, 0.49]) for Asian population. To sum up, this meta-analysis showed that TNF-α T-1031C polymorphism was associated with EM susceptibility and has a protective effect in Asian and European populations.