The two patients were double-heterozygous for the p.(Arg3500Gln) APOB mutation and either the p.(Trp66Gly) or p.(Glu207Lys) LDLR mutations reflecting an unusual phenotype of “aggravated hypercholesterolemia.” The two missense mutations in LDLR were previously detected in a French Canadian cohort, and the p.(Arg3500Gln) APOB is a founder mutation in Northern Europe (Leitersdorf et al., 1990; Benlian et al., 1996). Here, APOB is linked to familial hypercholesterolemia.