To clarify whether peripheral differentiation of TGFβ-dependent inducible Treg (iTreg) cells was the cause of hypercholesterolemia-mediated increase of Treg cell populations, we analyzed markers that were reported to distinguish thymic-derived Treg (tTreg) cells from iTreg cells. The gene discussed is TGFB1; the disease is familial hypercholesterolemia.