Subsequently, we analyzed by Sanger sequencing the DNA of 127 French probands with hypercholesterolemia in whom we excluded the known mutations in LDLR, APOE and PCSK9 genes and fragments of exons 26 and 29 of APOB, to look for the p.Arg50Gln variation in the APOB gene. Here, PCSK9 is linked to familial hypercholesterolemia.