A recent study reported FGF21 serum levels to be significantly increased in PCOS patients compared to women without PCOS, suggesting the possible involvement of FGF21 in PCOS [218], supported by a previous study reporting elevated FGF21 levels in PCOS patients, which were associated with levels of testosterone, LH and with BMI [219]. This evidence concerns the gene PLOD1 and polycystic ovary syndrome.