Von Willebrand Disease Type 2A: An Update

Dysfunctional or quantitatively deficient von Willebrand factor (VWF) underlies von Willebrand disease (VWD), the most common inherited bleeding disorder. Type 2A VWD is a qualitative defect marked by impaired VWF-dependent platelet adhesion, typically reflected in disproportionately reduced ratios of platelet-dependent VWF activity to antigen (VWF activity/VWF:Ag) and collagen binding to antigen (VWF:CB/VWF:Ag). This phenotype results from a selective reduction or lack of high- and intermediate-molecular-weight multimers, which are essential for effective hemostasis under high shear stress. The lack of multimer arises from impaired multimer assembly and/or increased proteolytic cleavage of VWF by ADAMTS13. Clinically, type 2A tends to present with greater severity than other type 2 variants, manifesting as mucocutaneous bleeding, often including heavy menstrual bleeding, epistaxis, post-surgical bleeding and gastrointestinal hemorrhage from angiodysplasia. Diagnosis relies on functional assays and VWF multimer analysis, supported by genetic testing that identifies subtype-specific mutations affecting VWF multimeric structure and therefore its function. Type 2A is typically inherited in an autosomal dominant manner, with rare exceptions of autosomal recessive inheritance. Structural and molecular studies are continuing to elucidate how domain-specific variants disrupt multimeric structure and thus interactions with its ligands. Management is guided by bleeding severity and includes desmopressin (following responsiveness testing) and VWF replacement therapy. This review provides an in-depth update on type 2A VWD, covering its epidemiology, pathophysiology across distinct subtypes, clinical manifestations, diagnostic approach, molecular and structural insights, and current therapeutic strategies.