Investigation of Polymorphisms in the Upstream Sequence of LIF and LIFR Genes in the Infertile Women

During pregnancy, the embryo implantation stage is a highly dynamic and molecularly controlled phenomenon. Several genes are involved in the implantation process, among which the leukemia inhibitory factor (LIF) is a marker of implantation. LIF is a multi-functional cytokine located on chromosome 22. The expression of this gene is increased in the middle of the secretion phase from the sexual cycle, and any defect in its expression will cause the implantation failure. LIF receptor or LIFR gene, as the LIF receptor, consists of two membrane proteins called LIFR and GP130. LIFR acts as a signal receptor for LIF in a low-affinity level. In this study, we focused on the screening of polymorphisms in the promoter region of the LIF and LIFR genes in the infertile women using the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) method. In this study, blood samples were collected from 100 women with primary and secondary infertility and 50 healthy women as a control group. Extraction of DNA was done by the phenol-chloroform method, and in the next step, using specific primers for upstream regions of the LIF and LIFR genes, target sequences were amplified and analyzed by the SSCP method. Finally, PCR products with different configurations were selected for sequencing analysis. The results showed two polymorphisms in the upstream region of LIF and LIFR genes of two women, but there were no genetic changes in the control group. The present study was the first in this field, and the results indicated the importance of examining such genes in infertility with an unknown cause.