Unlike FVIII, FIX modified in this manner can also be used to treat theinhibitor form of hemophilia A. The introduction of a gene therapy plasmidencoding mutein FIX with the triple substitution V181I, K265T, and I383V intoFVIII gene knockout mice improved the blood clottingindicators [187], thus attesting to thefact that the hemostatic function in patients with hemophilia A can berecovered without using FVIII drugs (Fig. 8I). Here, F8 is linked to hemophilia A.