The study involving apolipoprotein E knockout mice infected with Leishmania donovani showed the important role of Apo E in protection against visceral leishmaniosis by displaying hypercholesterolemia, host-protective cytokines, and expansion of antileishmanial CD8 + IFN-γ + and CD8 + IFN-γ +TNF-α + T cells [31]. The gene discussed is TNF; the disease is familial hypercholesterolemia.