A promising approach to treat PCOS is the use of combination of MF with the other drugs that improve the ovarian function and metabolic parameters in PCOS, with the best candidates for co-administration are CC, a mild nonsteroidal estrogen antagonist belonging to the family of selective estrogen receptor modulators, and letrozole, a non-steroidal aromatase inhibitor that prevents the conversion of androgens to estrogens [116,131,143,144,145,146,147,148]. This evidence concerns the gene ESR1 and polycystic ovary syndrome.