Hemophilia

Descriptive text is not available for this imageBASICS

DESCRIPTION

  • Hemophilia A and B are the most common inherited bleeding disorders.
  • These are chronic conditions that require lifelong medical care.
  • Hemophilia A is a factor VIII deficiency, and hemophilia B is a factor IX deficiency.
  • Bleeding phenotype is dependent on the baseline percentage of clotting factor activity.

EPIDEMIOLOGY

  • Hemophilia affects in 30/100,000 male births.
  • Prevalence: 80–85% have hemophilia A, and 15–20% have hemophilia B.

ETIOLOGY

  • Characterized by a defect in secondary hemostasis at the level of the coagulation cascade
  • Factor X activation requires factor VIII and factor IX for normal thrombin generation, and therefore, a deficiency in either factor VIII or factor IX impairs the body’s ability to generate thrombin and fibrin.

RISK FACTORS

  • X-linked recessive inheritance pattern
  • Genetics: 2/3 of patients have a family history; 1/3 exhibit de novo mutations.
    • Inversion of intron 22 occurs in 45% of factor VIII gene defects.
    • Missense point mutations occur in 60% of factor IX gene defects.
  • It is important to be aware of the family history to assess carrier status as well as genetic prenatal testing (performed via amniocentesis or chorionic villus sampling).
  • At birth, factor levels can be sent from cord blood (factor IX levels must be interpreted for age adjusted values).

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