PCSK9 and familial hypercholesterolemia: Familial hypercholesterolemia (FH) (OMIM, 606945) [14] has been associated with mutations in genes encoding the LDL receptor (LDLR), the apolipoprotein B-100 (ApoB-100, a ligand of the LDL-C receptor), and proprotein convertase subtilisin kexin type 9 (proprotein convertase, subtilisin/kexin-type 9, PCSK9).