Studies of multimerin in patients with von Willebrand disease and platelet von Willebrand factor deficiency

In normal platelet α‐granules von Willebrand factor (VWF) is stored with multimerin and factor V in an eccentric electron‐lucent zone. Because the platelet stores of VWF are deficient in ‘platelet low’ type 1 and type 3 von Willebrand disease (VWD), we investigated their electron‐lucent zone proteins. The patients with VWD had partial to complete deficiencies of plasma and platelet VWF but normal α‐granular multimerin and factor V, and normal α‐granular fibrinogen, thrombospondin‐1, fibronectin, osteonectin and P‐selectin. In type 3 VWD platelets, α‐granular electron‐lucent zones lacking VWF‐associated tubules were identified and multimerin was found in its normal α‐granular location. These findings indicate that the formation of the electron‐lucent zone and the sorting of multimerin to this region occur independent of VWF. The isolated abnormalities in VWF suggests a VWF gene mutation is the cause of ‘platelet low’ type 1 VWD.

Studies of multimerin in patients with von Willebrand disease and platelet von Willebrand factor deficiency Journal Articles