The action of the female hormone, estrogen, is mostly mediated by estrogen receptors (ERs), whose action on sterility, infertility, or subfertility and sexual behavior have been thoroughly investigated using selective ER modulators, ERα- and ERβ-knockout (KO) mice (Bondesson et al., 2015, Chen et al., 2009, Dupont et al., 2000), and ERα-, ERβ1-, and ERβ2-KO zebrafish (Lu et al., 2017). Here, ESR1 is linked to Infertility.