von Willbrand Factor (vWF)

With a prevalence of 0.03 to 0.1% the von Willebrand disease is the most frequent bleeding disorder. The von Willebrand factor (VWF) has two important functions in hemostasis: First, it promotes the adhesion of blood platelets to the injured vessel wall and secondly it functions as a carrier protein for factor VIII and protects it as a chaperone from premature inactivation. The VWF is a glycosylated protein, that is organized in multimers. The size of the VWF multimers is regulated in vivo by a specific plasmatic protease. The lack or a severe reduction of the VWF cleaving metalloprotease ADAMTS-13 is associated with the thrombotic thrombocytopenic purpura (TTP).  

There are three main types of VWD. VWD types 1 and 2 are autosomal dominant traits, while type 3 is inherited autosomal recessive. VWD type 1 is characterized by a quantitative deficiency of the VWF. The VWF is dysfunctional in type 2, and absent in type 3 VWD.

The differential diagnosis of VWD types and subtypes (VWD type 2) requires multiple test, covering most of VWF functions.

Normal ⇔

Increased ⇧

Reduced ⇩…slightly, ⇩⇩…moderately, ⇩⇩⇩…sever, 0…absent

VWF:CB … Collagen Binding; VWF:Ag ... Antigen; VWF:RCo ... Ristocetin Cofactor, RIPA ... ristocetin-induced platelet agglutination; FVIII:C … FVIII Activity

LITERATURE