F8 and hemophilia B: Although a good deal of progress has been made using CRISPR/Cas9-mediated gene editing to correct hemophilia B (HB), only a few studies have reported using this approach to attempt to correct HA (70–79), due in large part to the difficulty of achieving CRISPR/Cas9-mediated knock-in of a transgene with the increased length and complexity of FVIII (80, 81).