The IDO1 involvement in restraining FVIII antibody responses in hemophilia has been further confirmed by the study of Matino et al. where both IDO1 expression in hemophilic patients with or without inhibitor and the impact of IDO1 activity restraining FVIII alloantibodies in hemophilic mouse (i.e., F8 KO mice) were investigated (76). The gene discussed is F8; the disease is hemophilia.