Medical treatment of endometriosis utilizes gonadotropin-releasing hormone (GnRH) analogs, which block the ovarian hormones leading to amenorrhea (8); low doses of such drugs should be combined with female hormones (i.e., low-dose progestins) to reduce climacteric-like symptoms and improve tolerability and adherence to therapy (29). This evidence concerns the gene GNRH1 and endometriosis.