The -351A>G genetic polymorphism in the estrogen receptor alpha gene and risk of endometriosis: a case-control study

Background: The major issue to address in endometriosis etiology is to identify the genetic changes in the disease and their occurrence in different populations. Uncovering these genetic changes may be important in developing potential biomarkers for early diagnosis and prognosis of endometriosis. Among all endometriosis susceptibility genes studied before, convincing association has been found with variants in the estrogen receptor alpha (ESR1) gene and this disease; however, the contributions of these genetic variants in different populations and ethnic groups are not similar. Accordingly, this study was carried out to replicate the previous findings to assess whether this polymorphism is associated with endometriosis in Iranian women. Methods: A case-control study was designed to determine the possible association between ESR1-351A>G variant and occurrence of endometriosis. The study group consisted of 100 subjects diagnosed with endometriosis as case group and 100 fertile women without endometriosis as controls recruited from subjects referred to the Tehran Women’s General Hospital between January to September 2013. All subjects were genotyped for this marker using amplification refractory mutation system- polymerase chain reaction (ARMS-PCR). Association of risk allele (G) with endometriosis was as-sessed using PLINK software after age adjustment. Results: The results showed that the genotype frequencies were in Hardy-Weinberg Equilibrium (HWE) in both case (F=0.04, P:0.67) and control (F=0.02, P:0.83) groups. In addition, there were no significant differences between case and control groups in terms of genotype frequencies (P=0.17). Moreover, the results indicated that the presence of risk allele (G) did not significantly increase risk of endometriosis (OR: 1.43, 95%CI: 0.96-2.13, P=0.07). Conclusion: The results do not support the previous findings of an association between -351A>G genetic polymorphism in ESR1 gene and endometriosis. Therefore, comprehensive genetic approaches including linkage analyses and family-based tests, together with a number of replication studies with large sample size, are needed to make conclusive claims about the role of this genetic polymorphism in susceptibility to endometriosis