Previous studies have indicated that the overactivated CNP/NPR2 system in follicles is involved in the formation of polycystic ovary syndrome (PCOS), which is specifically manifested by the abnormal elevation of Nppc/NPPC and Npr2/NPR2 in follicles of PCOS mouse models and human patients [37,38]. Here, NPPC is linked to polycystic ovary syndrome.