Hemophilia

Basics

Description

  • 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:
    • 5–40% factor activity (mild hemophilia):
      • Bleeding with major trauma or surgery
    • 1–5% factor activity (moderate hemophilia):
      • Bleeding secondary to trauma/surgery
      • Occasional spontaneous bleeding
    • <1% factor activity (severe):
      • Spontaneous bleeding
  • 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

Etiology

Genetics

  • X-linked recessive, though 30% have a spontaneous mutation
  • Rare disease:
    • Hemophilia A: 1 in 5–7000 males
    • Hemophilia B: 1 in 30,000 males
  • Prevalence of inhibitors: Up to 40% of severe hemophilia A and <5% of hemophilia B

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