F9 and hemophilia B: We have previously reported that, upon intravenous administration, LV allow stable gene transfer to the liver, provided that transgene expression is stringently targeted to hepatocytes, and have shown dose‐dependent therapeutic efficacy in a mouse and a canine model of hemophilia B, a coagulation disorder due to mutations in the factor IX (FIX)‐encoding gene (Brown et al, 2006; Matrai et al, 2011; Cantore et al, 2012, 2015).