FNDC5 and polycystic ovary syndrome: By analyzing the data, Wang et al. found that the serum irisin level of PCOS patients was significantly lower than that of non-PCOS patients, the serum irisin level of obese PCOS patients was significantly lower than that of non-obese PCOS patients; however, the serum irisin level of PCOS patients with dyslipidemia was significantly higher than that of PCOS patients with normal lipids [15].