PCSK9 and Hypercholesterolemia: For instance, the knowledge that rare individuals lacking proprotein convertase subtilisin/kexin type 9 (PCSK9) have better lipid profiles and are protected from atherosclerosis and myocardial infarctions was an important factor in rapid development and approval of PCSK9 inhibitor for treatment of hypercholesterolemia [7], [8], [23], [73].