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. The gene discussed is PCSK9; the disease is familial hyperaldosteronism.