Hemophilia A and B are rare inherited bleeding disorders, caused by mutations in the F8 or F9 gene on the X-chromosome leading to a deficiency of coagulation factor VIII (FVIII) or coagulation factor IX (FIX), respectively. As a result, persons with decreased coagulation FVIII/IX levels have an increased bleeding tendency. Classification of disease severity is based on the endogenous FVIII/IX level, ranging from severe (FVIII/IX