SERPINE1 and polycystic ovary syndrome: Two polymorphisms of the plasminogen activator inhibitor-1 (PAI-1) gene are also very important in the context of the development of PCOS and infertility: −675 5 G > 4 G (rs1799889) and −844 G > A (rs2227631), which are associated with increased transcriptional activity and PAI-1 protein levels [47].