• Caused by deficiency of functional factor VIII or factor IX
  • Lack of functional factor causes partial inactivation of coagulation cascade and impaired hemostasis
  • 2 types:
    • Hemophilia A: Factor VIII deficiency
    • Hemophilia B (Christmas disease): Factor IX deficiency
  • Symptoms dependent on factor activity:
    • 5–30% factor activity (mild hemophilia):
      • Bleeding with major trauma or surgery
    • 1–5% factor activity (moderate hemophilia):
      • Bleeding secondary to trauma/surgery
      • Occasional spontaneous hemarthroses (<1 time per month)
    • <1% factor activity (severe):
      • Spontaneous bleeding from infancy
      • May bleed as often as 1–2 times per week, often requiring factor replacement
  • Complications:
    • Death from hemorrhage
    • Recurrent joint bleeding leads to joint destruction and loss of function
    • Transfusion-transmitted infections (risk reduced with purification of concentrates)
    • Development of inhibitors (IgG antibodies to factors), which prevent hemostasis


  • X-linked recessive, though 1/3 have a spontaneous mutation
  • Rare disease:
    • Hemophilia A: 1 in 5–7,000 males
    • Hemophilia B: 1 in 30,000 males
  • Prevalence of inhibitors: 20% of severe hemophilia A and <5% of severe hemophilia B

There's more to see -- the rest of this topic is available only to subscribers.