Once other causes responsible for aPTT prolongation have been excluded such as lupus anticoagulant, inherited coagulation factor deficiencies, heparin, or oral anticoagulant treatment, the diagnosis of AHA is confirmed through the evidence of low FVIII levels and finally via the detection of an anti-FVIII antibody, quantified in Bethesda Units (BU) [7]. The gene discussed is F8; the disease is autoimmune hemolytic anemia.