44 women with recurrent implantation failure (RIF), 63 women who had children via IVF and 65 fertile women with children and no history of miscarriage were studied. Women who had a polymorphism in ESR1 and LIF had increased chances of presenting with RIF. They concluded that ER1 and LIF polymorphisms can predict RIF. The gene discussed is ESR1; the disease is spontaneous abortion.