LDLR and familial hypercholesterolemia: Elevated serum LDL-C levels result from the inability of familial hypercholesterolemia (FH) patients to clear circulating cholesterol caused by mutations in any of the major genes involved in LDL uptake, including LDL receptor [33], apolipoprotein B [34], proprotein convertase subtilisin/kexin type 9 (PCSK9) [35], and low-density lipoprotein receptor adaptor protein 1 (LDLRAP1) [36].