Abstract
Anti factor IX antibodies (FIX inhibitors) develop in 1.5-3% of congenital hemophilia B patients as alloantibodies and are very rarely seen in non-hemophilic individuals as autoantibodies. The incidence of FIX inhibitor development in hemophilia B is very low in contrast to hemophilia A. In particular, an allergic reaction to an exogeneous FIX protein is a major peculiarity among these patients. Due to the low incidence and small number of cases, there has been insufficient basic and clinical research to properly investigate FIX inhibitor development in congenital hemophilia B patients. Recently, several risk factors, including genetics and environment, for inhibitor formation have been hypothesized. The clinical manifestations and progress in both the treatment for bleeding and inhibitor eradication and the risk factors of for FIX inhibitor development will be introduced in this review.
