APOB and familial hypercholesterolemia: Familial hypercholesterolemia (FH) is an autosomal dominant inherited metabolic disorder caused by mutations in low-density lipoprotein (LDL) receptor (LDLR), apolipoprotein B-100 (Apo B), proprotein convertase subtilisin/kexin type 9 (PCSK9), or LDLR adaptor protein 1 (LDLRAP1) genes.