To address the role of amino acid substitutions that cause mild/moderate hemophilia A in the intracellular trafficking of FVIII, we have created 5 FVIII variants in B-domain deleted FVIII-YFP that have been established to cause mild to moderate hemophilia A due to reduced binding to VWF [21]–[24], including single Tyr1680Phe, Ser2119Tyr, Arg2150His, Del2201 or Pro2300Ser substitutions. This evidence concerns the gene VWF and hemophilia A.