Comparison between the clinical and laboratory features found in Haemophilia A, Haemophilia B and Von Willebrand's disease
Haemophilia A | Haemophilia B | Von Willebrand's disease | |
Mode of inheritance | X-linked | X-linked | Autosomal Dominant (incomplete) |
Main sites of Bleeding | muscle, joints, following trauma or post operation | muscle, joints, following trauma or post operation | skin cuts, mucous membranes, following trauma and post operation |
platelets | normal platelet count | normal platelet count | normal platelet count |
bleeding time | normal | normal | prolongation of bleeding time |
prothrombin time | normal | normal | normal |
Activated partial thromboplastin time (APTT) | prolonged | prolonged | prolonged |
von Willebrand's Factor | normal | normal | reduced levels |
factor VIII | low levels | normal | low levels - vWF is the carrier molecule for factor VIII thus preventing it from premature destruction - this property explains the reduced factor VIII levels found in von Willebrands disease |
factor IX | normal | low levels | low levels |
ristocetin-induced platelet aggregation | normal | normal | ristocetin fails to induce platelet aggregation in von Willebrand's patients because of lack of vWF:R - a cofactor for ristocetin |
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