Familial hypercholesterolemia (FH), affecting between 1:250 and 1:300 individuals worldwide, is caused mainly by loss-of-function mutations in LDL receptor (LDLR) and less commonly in APOB and by gain-of-function mutations in proprotein convertase subtilisin/kexin type 9 (PCSK9) (2). The gene discussed is LDLR; the disease is familial hypercholesterolemia.