PAPPA (Pregnancy-Associated Plasma Protein A): PAPPA is a protease that regulates the availability of insulin-like growth factors (IGFs) by cleaving their binding proteins. It plays a crucial role in fetal development and is used as a biomarker in prenatal screening for aneuploidies. Abnormal levels of PAPPA are associated with adverse pregnancy outcomes, including preeclampsia and intrauterine growth restriction.