Since Hansson et al. found that 30 mg/kg (300 IU/kg) recombinant human prothrombin reduced tail transection bleeding in hemophilia A and hemophilia B mice to wild-type levels22, we assessed 36–600 IU/kg doses in induced pan-factor deficiency, finding 36 IU/kg sufficient to reduce tail transection blood losses to mFFP-treated levels. The gene discussed is F2; the disease is complement factor I deficiency.