FACTOR-IX INHIBITORS IN HEMOPHILIA-B PATIENTS - THEIR INCIDENCE AND PROSPECTS FOR DEVELOPMENT WITH HIGH-PURITY FACTOR-IX PRODUCTS

In most respects, haemophilia B with inhibitors against FIX cannot be distinguished from haemophilia A with inhibitors. However, based on a 19 nation survey and on several published reports, inhibitors occur about five-fold less often in haemophilia B than in haemophilia. A. The most interesting question, however, is why most patients do not develop inhibitors. This might be due to materno-foetal transfusions or to the transfer of antigens by breast feeding.