F8 and hemophilia: AHA: acquired hemophilia A; anti-pFVIII: anti-porcine FVIII; aPTT: activated partial thromboplastin time; CDC: Centers for Disease Control; ELISA: enzyme-linked immunosorbent assay; FVIII: factor VIII; HTC: hemophilia treatment center; rFVIIa: recombinant activated factor VIIa; rpFVIII: recombinant porcine factor VIII