P-244: Analysis of Genomic and Cell Free DNA of A let-7 microRNA Binding Site of KRAS Gene Polymorphisms in Endometriosis

Background: Endometriosis is one of the most common benign gynecological diseases which is characterized by endometriallike tissue growing outside the uterine cavity. Although the pathology of endometriosis remains unknown, the genetic predisposition plays an apparent role. Several genes have been contributed to endometriosis, but it seems KRAS has a crucial role, because its activation results in de novo endometriosis in mice. We screened women with endometriosis for a polymorphism in a let-7 microRNA binding site of KRAS, in genomic DNA and cell free DNA, which are associated with the risk of endometriosis in Iranian people Materials and Methods: We investigated 58 patients with histopathologically or laparatomy confirmed endometriosis and 60 control group women who were surgically proven to have no endometriosis in Firoozgar hospital. Participants were interviewed in a structured questionnaire that included questions about demographics, weight and height, menstrual history, pregnancy history, contraceptive methods and family history of endometriosis. Genomic DNA and Cell free DNA (CFD) of cell blood and plasma of each patient were extracted separately. Identification of let-7 microRNA family complementary site 6 (LCS6) in 3'UTR of KRAS polymorphic variant (rs61764370) was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).The 699 bp PCR product was digested with the endonuclease PfeI (TfiI). Results were confirmed by sequencing analysis. Results: 1 (1.72%) patient with endometriosis and 4 (6.66%) subjects without endometriosis carried minor allele at KRAS LCS6 SNP. The allele frequency of this SNP in CFD was 0 and 4.76% in case and control group respectively. Conclusion: Although researchers in Yale university (2012) reported high frequency (31%) of KRAS LCS6 SNP as a marker for endometriosis risk, our results suggest that this SNP, in genomic DNA and CFD, have no statistically significant association with endometriosis in Iranian population and this is not a useful marker of endometriosis risk in our population.