Proprotein convertase subtilisin⁄kexin 9 (PCSK9) is a secreted glycoprotein that regulates the degradation of the low-density lipoprotein receptor. Sin-gle nucleotide polymorphisms in its gene associate with both hypercholes-terolemia and hypocholesterolemia, and studies have shown a significant reduction in the risk of coronary heart disease for ‘loss-of-function’ PCSK9 carriers.