Patients with hemophilia A and B who have developed inhibitory antibodies against factor VIII (FVIII) or factor IX (FIX), are successfully treated with by-passing agents such as FEIBA, an activated prothrombin complex concentrate derived from human plasma [1], or recombinant activated factor VII (rFVIIa), to control and prevent bleeding. The gene discussed is F9; the disease is hemophilia A.