In our patient in 2018 treatment was switched from regular prophylaxis of hemophilia A to 4000 international units (IU) of recombinant FVIII Fc fusion protein (rFVIIIFc) efmoroctocog alfa (Elocta®, Sobi-Biogen) twice weekly, equivalent to 106.7 IU/kg at a body weight of 75 kg. The gene discussed is F8; the disease is hemophilia A.