The VWF gene is located on chromosome 12 and numerous mutations have been identified
Pathophysiology
As VWF has a critical role as an adhesive protein in the platelet vessel wall interaction, the absence of VWF leads to impaired platelet adhesion to the subendothelium
Reduced VWF levels also lead to factor VIII deficiency, as factor VIII is not protected from premature degradation
Clinical presentation
Clinical features depend on mutation - range from mild (bleeding following minor trauma or surgery, epistaxis and menorrhagia often occur) to more severe bleeding
Investigations
Bloods
FBC - may be normal or may show microcytic anaemia or low platelet count
Coagulation tests - APTT may be normal or may be prolonged if factor VIII deficiency is present, PT will be normal
VWF antigen test, factor VIII clotting activity test
Specialised VWF testing e.g. von Willebrand factor multimer test
Management
Depends on severity
May involve use of desmopressin
Although recombinant VWF is becoming available, plasma-derived factor VIII concentrates that contain intact VWF are the mainstay of replacement therapy
Used to treat bleeding or to cover surgery, or in those who do not respond adequately to desmopressin
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