It was not very clear whether double-heterozygous FH cases carrying LDLR/PCSK9 mutations can lead to similar severe phenotype until Pisciotta et al. (2006a) reported two unrelated double-heterozygous FH carrying LDLR/PCSK9 mutations with clinical phenotype and family history similar to that of the HoFH. This evidence concerns the gene LDLR and familial hyperaldosteronism.