Recently, the “United Kingdom Haemophilia Centre Doctors’ Organisation” (UKHCDO) published recommendations for measuring FVIII in AHA patients in treatment with rpFVIII, excluding the use of the chromogenic assay (CSA) due to its high underestimation of FVIII levels except in the case of patients with AHA who receive emicizumab; however, the latter eventuality is still an off-label treatment [23]. The gene discussed is F8; the disease is autoimmune hemolytic anemia.