LDLR and familial hypercholesterolemia: Furthermore, patients with homozygous familial hypercholesterolemia harboring LDL receptor (LDLR) null mutations or with autosomal recessive hypercholesterolemia cannot be effectively treated by current available lipid-lowering drugs, such as statins and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors (5).