Second, all 4 subjects carried LDLR variants in the LDLR gene, and kinetic results may differ in hoFH carrying variants in other FH-causing genes, namely APOB, PCSK9, and LDLRAP1. Furthermore, different infusion and lipoprotein isolation protocols were used at the 2 participating centers and may have contributed to some variability in the fit of the compartmental model and, ultimately, to some variability in the kinetic results. Here, APOB is linked to familial hyperaldosteronism.