• Definition

    Hemophilia refers to a group of bleeding disorders in which it takes a long time for the blood to clot.

    Related topics:

    • Hemophilia A
    • Hemophilia B
    • Von Willebrand disease

    Causes, incidence, and risk factors

    When you bleed, the body launches a series of reactions that help the blood clot. This is called the coagulation cascade. The process involves special proteins called coagulation factors. When one or more of these clotting factors are missing, there is usually a higher chance of bleeding.

    Hemophilia is caused by a lack of enough factor VIII or IX. In most cases, hemophilia is passed down through families (inherited). It most often affects males.