,201,211,212 The understanding of which assay best predicts in vivo hemostatic function of hepatocyte-derived FVIII/FIX-R338L is relevant to guide clinical management because sustained FVIII:C/FIX:C, depending on the assay used, crosses clinical thresholds of mild/moderate hemophilia,152,155 normal FVIII:C/FIX:C (Harrington et al., 2020, WFH Virtual Summit, conference),145,146 and supratherapeutic FVIII:C/FIX:C (Harrington et al., 2020, WFH Virtual Summit, conference).145. Here, F8 is linked to hemophilia.