SMAD9 and polycystic ovary syndrome: For the known genes related to follicle development and steroid metabolism, AMH, FSHR, ESR2, DDX4, and SMAD9 expression was upregulated in the GCs of PCOS patients, while INHA, SOD2, and CYP11A1 expression was downregulated (Supplementary Figures 2C,D).