SFRP4 and polycystic ovary syndrome: PSG4, CFI, CHI3L1, BDKRB2, GUCY1A2, SFRP4, IL33, and PADI2 were upregulated in the control group but downregulated in the PCOS group in both datasets, and PITX1, ISG15, NEURL1, OAS2, PRSS3, PI16, L3MBTL4, and MX2 were downregulated in the control group but upregulated in the PCOS group in both datasets.