Hemophilia A
Write a short note on hemophilia A.
Answer:
Hemophilia A
Classic hemophilia or hemophilia A is the second most common hereditary coagulation disorder.
- This is due to the defiiency or reduced activity of factor 8 (Antihemophilic factor)
- This disorder is inherited as a sex-linked recessive trait and therefore manifest clinically in males while females are the carriers.
Hemophilia A in boys
“Biomechanics of clotting factor deficiencies in hemophilia A”
Hemophilia A Pathogenesis
Hemophilia A is caused by quantitative reduction of factor 8 in 90% of cases while 10% cases have normal or increased level of factor 8 or either reduced activity.
Synthesis of factor 8 occurs in hepatic parenchymal cells and it regulates activation of factor X in intrinsic coagulation pathway.
“Understanding hemophilia A: Causes and symptoms”
Circulation of factor 8 occur in the blood which is complexed to another large protein, i.e. von Willebrand’s factor which consists of 99% of factor 8 – von Willbrand complex.
Genetic coding, synthesis and function of von Willebrand factor are diffrent as compared to those of factor 8. Normal hemostasis needs 25% of factor 8 activity.
Why do boys bleed more
Hemophilia A Clinical Features
- Patient with hemophilia suffrs from bleeding for hours or day after injury.
- Hemophilic bleeding can involve any bleeding but occurs most commonly as recurrent painful hemarthroses and muscle hematomas and sometimes hematuria.
Hemophilia A Laboratory Findings
“Importance of early diagnosis of hemophilia A in boys”
- Whole blood coagulation time is prolonged in severe cases.
- Prothrombin time is usually normal.
- Activated partialthromboplastintime is typicallyprolonged.
- Specifi or assay for factor VIII show lowered activity.
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