LDLR and familial hypercholesterolemia: Drugs specifically targeting genes or gene products involved in lipoprotein metabolism may therefore have unintended effects.6,7 Pathogenic variants in proprotein convertase subtilisin/kexin type 9 (PCSK9), apolipoprotein B (APOB), and low-density lipoprotein receptor (LDLR) can lead to familial hypercholesterolemia (FH).