Acute gonadotropin-releasing hormone (GnRH) agonism or human chorionic gonadotropin injection are used to evaluate ovarian steroidogenesis in vivo, and women with PCOS show that these stimuli result in enhanced 17-hydroxyprogesterone (17OHP) and androstenedione responses [3]. The gene discussed is GNRH1; the disease is polycystic ovary syndrome.