F9 and hemophilia A: Prolonged half-life drugs, developed with FC fusion technology, produced with recombinant DNA technology in a line of human embryonic cells: ELOCTA (recombinant factor VIII, efmoroctocog alfa) for haemophilia A—and ALPROLIX (recombinant factor IX, eftrenonacog alfa) for haemophilia B. These are drugs made thanks to genetic engineering: the coagulation factor is melted in the FC portion of the specific immunoglobulin (a particular antibody): in this way it is possible to use a natural pathway for prolong the residence time of therapy in the body (half-life).