Background and purpose: Endometriosis is a benign disorder defined by the presence of endometrial tissue out of pelvic cavity and is related to debilitating pelvic pain and infertility. MiRNAs, are a cluster of small endogenous noncoding RNA that bind to 3׳ UTR of target mRNA and cause mRNA degradation or repressing translation of mRNA. Mir-126 is a type of miRNA that is involved in many vital processes such as invasion and angiogenesis. In this study, mir-126 rs4636297 G/A gene polymorphism was compared between infertile women with endometriosis and healthy women.

Materials and methods: This analytical study was done in 72 infertile women with endometriosis and 252 healthy women as a control group. After extraction of genomic DNA from peripheral blood samples, desired polymorphism was genotyped using Tetra-ARMS-PCR method. Statistical analysis was performed using SPSS ver. 17. Genotype distributions and allelic frequencies of mir-126 rs4636297 gene polymorphism were compared between patient and control groups by Logistic regression analysis.

Results: A significant association was found between A allele of rs4636297 mir-126 polymorphism and endometriosis (OR: 0.6, 95% CI: 0.4-0.84, P= 0.005). In the dominant model of A allele (comparison between AA+AG VS. GG), AA+AG had protective effect on endometriosis (OR: 0.48, 95% CI: 0.28-0.82, P= 0.007).

Conclusion: There is a significant association between rs4636297 mir-126 polymorphism and susceptibility to endometriosis.