Von Willebrand disease type 2B

Von Willebrand disease type 2B (VWD type 2B) is a rare inherited bleeding disorder caused by gain-of-function mutations in the VWF gene located on chromosome 12. It is a qualitative variant of von Willebrand disease characterized by an increased affinity of von Willebrand factor (VWF) for the platelet glycoprotein Ib (GPIb) receptor. This enhanced binding leads to spontaneous platelet aggregation in the circulation, resulting in the selective clearance of both high-molecular-weight VWF multimers and platelets from the bloodstream. Consequently, patients typically present with thrombocytopenia (low platelet count) and a loss of large VWF multimers, both of which contribute to a bleeding tendency. The primary body system affected is the hemostatic (blood clotting) system. Key clinical features include mucocutaneous bleeding such as easy bruising, prolonged bleeding from cuts, epistaxis (nosebleeds), menorrhagia (heavy menstrual bleeding in women), and excessive bleeding after surgery or dental procedures. Thrombocytopenia is a distinguishing feature of type 2B compared to most other forms of von Willebrand disease and may fluctuate, sometimes worsening during physiological stress, pregnancy, or infection. The condition can be confused with immune thrombocytopenia (ITP) if the underlying VWF abnormality is not recognized. Diagnosis is supported by ristocetin-induced platelet aggregation (RIPA) testing, which shows enhanced aggregation at low ristocetin concentrations, along with multimer analysis demonstrating loss of high-molecular-weight multimers and genetic testing confirming VWF mutations. Treatment of VWD type 2B requires careful consideration. Desmopressin (DDAVP), which is commonly used in other forms of VWD, is generally contraindicated in type 2B because it can worsen thrombocytopenia by releasing abnormal VWF that further binds and clears platelets. Instead, treatment typically involves VWF-containing factor concentrates (plasma-derived VWF/FVIII concentrates) to replace functional VWF and correct hemostasis. Platelet transfusions may be needed in cases of severe thrombocytopenia or significant bleeding. Antifibrinolytic agents such as tranexamic acid can be used as adjunctive therapy for mucosal bleeding. Management during pregnancy requires close monitoring, as thrombocytopenia may worsen significantly, posing risks for both mother and child.

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