In addition an alloantibody to FVIII develops in 20% to 40% of congenital hemophilia patients who are treated with factor FVIII.[6] Autoantibodies against FVIII occur in approximately 0.2–1.0 cases per million per year in nonhemophilia.[7] The etiology of AHA is complicated and unknown; 46% of AHA patients are labeled idiopathic while more than 50% of cases are potentially associated with illnesses. Here, F8 is linked to hemophilia.