Pregnancy-associated plasma protein A: Abbreviated as PAPPA or PAPP-A. A large zinc-binding protein that acts as an enzyme, specifically a metallopeptidase. The gene for PAPPA is in chromosome band 9q33.1. PAPPA has been used in prenatal genetic screening and studies of atherosclerosis. Women with low blood levels of PAPPA at 8 to 14 weeks of gestation have an increased risk of intrauterine growth restriction, trisomy 21, premature delivery, preeclampsia, and stillbirth. PAPPA is present in unstable atherosclerotic plaques, and circulating levels are elevated in acute coronary syndromes which may reflect the instability of the plaques. PAPPA may be a marker of unstable angina and acute myocardial infarction (heart attack).