GWAS studies in women with endometriosis revealed numerous genes, including the genes associated with uterine development and stem cell function (WNT4), ovulatory function (ESR1, FSHB), and those regulating the activity of estrogen and estradiol biosynthesis (ESR1, GREB1, SYNE1, CYP2C19, CCDC170); most of these genes are also associated with ovarian cancer [68,69,70]. The gene discussed is ESR1; the disease is endometriosis.