Hemophilia Overview and Genetics

Study Notes

Hemophilia encompasses a range of bleeding disorders due to congenital deficiencies or dysfunctions of coagulation proteins.
Approximately 80% of hemophilia cases follow an X-linked recessive inheritance pattern.
The two primary types are hemophilia A (factor VIII deficiency) and hemophilia B (factor IX deficiency), with von Willebrand disease being another significant hereditary bleeding disorder.

Hemophilia A is characterized by a deficit in factor VIII, essential for thromboplastin formation in blood coagulation.
The severity of hemophilia correlates with the amount of factor VIII present; lower levels result in more severe symptoms.

Bleeding severity can vary widely, with around 60-70% of affected children having severe forms.
Common symptoms include prolonged bleeding, especially after minor injuries, and hemarthrosis (bleeding into joint cavities) typically affecting knees, elbows, and ankles.
Early hemarthrosis signs include joint stiffness and pain; severe cases present with swelling and limited mobility.
Spontaneous bleeding can occur, including hematuria and less frequently, epistaxis.
Internal bleeding risks include GI hemorrhage, retroperitoneal bleeding, and intracranial hemorrhages, which can be fatal.

Diagnosis relies on a history of bleeding episodes, evidence of X-linked inheritance, and abnormal laboratory tests, including a prolonged PTT.
Specific assays are used to measure factor VIII and factor IX levels.
DNA testing is available for carrier detection in families with hemophilia.

Treatment focuses on bleeding prevention and prompt intervention to mitigate tissue damage.
Factor VIII replacement can be administered through fresh blood or concentrated forms; dosing is calculated based on plasma volume.
Repeat infusions may be needed to maintain factor VIII activity levels.

Management strategies depend on the site of bleeding:
- Joint: Rest, ice, elevation, immobilization, physiotherapy.
- Soft tissue: Ice and elevation.
- Muscle: Similar to soft tissue with additional bed rest for iliopsoas muscle injuries.
- Mucous membranes: Pressure application for nosebleeds, topical agents, or nasal packing.

Prevention of bleeding includes reducing injury risk through safe environments and supervision during play.
Encourage age-appropriate exercises to strengthen muscles and joints while allowing for natural motor skill development.
Support families in preparing children for school integration regarding activity limitations.
Recommend protective gear for physical activities and guide families toward noncontact sports while advising against high-risk sports like boxing and football.

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