Several KEGG pathways were found to be closely linked with PCOS, including Prolactin signaling, Pentose phosphate pathway, Osteoclast differentiation, Thyroid cancer, endocrinal hormones biosynthesis, Non-alcohol fatty liver disease, Ovarian steroidogenesis, Lipid metabolisms and atherosclerosis, Cortisol synthesis and secretion, and Amphetamine addiction. The gene discussed is PRL; the disease is polycystic ovary syndrome.