Overview of inhibitors.

Inhibitory antibodies that develop in patients with hemophilia render standard therapy with factor concentrates ineffective. Several factors may influence inhibitor incidence, including genetics, the type of factor concentrate, and environment. A higher incidence of inhibitors in siblings compared to extended relatives, and in African Americans compared to Caucasians, suggests that genetics may play an important role in inhibitor development; however, genetic markers that indicate a predisposition for inhibitor development have yet to be identified. In addition, the appearance of inhibitors in immunologically challenged patients points to the role of the immune response system in the development of inhibitor antibodies, an area that warrants further study. Thus, the medical community faces the difficult task of developing new, improved therapies to combat inhibitors in patients with hemophilia, a task that will require careful consideration of the roles of environmental factors, the immune system, and genetics in inhibitor development.