The intentional transplacental delivery of disease-relevant antigens exploiting the FcRn as a Trojan horse from the mothers' circulation to the fetus' was recently validated in two experimental models of human diseases: T1D and alloimmunization to therapeutic FVIII in hemophilia A. Hemophilia A is a rare X-linked hemorrhagic disorder characterized by the lack of functional pro-coagulant FVIII. The gene discussed is F8; the disease is hemophilia A.