PCSK9 and familial hypercholesterolemia: Familial hypercholesterolemia (FH; OMIM #143890), caused mainly by mutations in the LDL receptor, proprotein convertase subtilisin/kexin type 9 (PCSK9), or apolipoprotein B (APOB) genes, is characterized by the clinical triad of primary hyper-LDL cholesterolemia, tendon xanthomas, and premature coronary artery disease (CAD) [1], although accumulation of common single nucleotide variations and/or other LDL-associated rare genetic variations may also contribute to cause this situation [2].