Besides familial hypercholesterolemia (FH) caused by ldlr mutations and familial defective apoB100 caused by apob mutations (1), autosomal dominant hypercholesterolemia can be caused by gain-of-function mutations in the pcsk9 gene, now commonly referred to as FH3 (3, 4). The gene discussed is PCSK9; the disease is familial hypercholesterolemia.