Laboratory Diagnosis of Congenital von Willebrand Disease

Abstract

Von Willebrand disease (vWD) is caused by quantitative or qualitative defects, or both, of the von Willebrand factor (vWF), a multimeric high-molecular glycoprotein (GP). Typically, it affects the primary hemostatic system, which is reflected by a mucocutaneous bleeding tendency simulating a platelet function defect. The vWF promotes its function in two ways: (1) by supporting platelet adhesion to the injured vessel wall under conditions of high shear forces and (2) by its carrier function for factor VIIIc (FVIIIc) in plasma. Because of the complexity of the disease, diagnosis of vWD is one of the most challenging of any coagulation disorder. The stepwise diagnosis of vWD includes patients and family history, screening procedures (bleeding time [BT], filter tests, platelet counts, activated partial thromboplastin time [aPTT]), confirmatory tests (vWF antigen [vWF:Ag], vWF ristocetin cofactor activity [vWF:RCo], vWF collagen-binding [vWF:CB] assay, ristocetin-induced platelet aggregation [RIPA], FVIIIc) and tests for final classification (multimeric analysis, FVIII binding capacity of vWF [vWF:FVIIIB], platelet vWF). In 1999, we classified 303 patients with congenital vWD as type 1 (n = 122), type 2 (n = 171), and type 3 (n = 10). Type 2 was further subdivided into type 2A (n = 126), type 2B (n = 17), type 2M (n = 22), and type 2N (n = 6). Type 2A showed a remarkable heterogeneity, with only 27.8% (n = 36) of the "classic" IIA pattern. The other high-frequency patterns were type IB (25.4% n = 32) and type IIE/F/H-like structural abnormalities (28.6% n = 36). The spectrum was completed with samples from patients with types 2D, 2C, 2C Miami, smeary structures, and other rare subtypes (together 18.9% n = 23).

Prophylactic fresh frozen plasma may prevent development of hepatic VOD after stem cell transplantation via ADAMTS13-mediated restoration of von Willebrand factor plasma levels

“…An inverse correlation between decreased ADAMTS13:AC and increased VWF:AG was thus seen in our VOD patients. These findings were consistent with previous 21,29,38), no apparent changes in VWF multimer patterns were found throughout SCT including the preconditioning period, when compared to patterns found in normal control plasma (d, e, f). The multimers over the dotted line indicate unusually large VWF multimers (UL-VWFM), which can never be detected in normal plasma.…”

“…The UL-VWFM was evaluated by SDS-0.9% agarose electrophoresis followed by western blotting with luminographic detection. 27,28 Multimers were defined as low molecular 29 Furthermore, the bands corresponding to higher molecular weight, which could never be detected in pooled normal plasma, were defined as UL-VWFM. VWF:AG was measured by a sandwich ELISA using a rabbit anti-human VWF polyclonal antibody (DakoCytomation, Kyoto, Japan).…”

Analysis of von Willebrand factor structure by multimer analysis

“…Subbanding structure differs in VWD Type 2B. lysates or plasma VWF from a TTP patient in remission should be run [11].…”

“…Multimer distribution may be arbitrarily defined as: small MWMs are the five fastest moving smallest multimers, intermediate MWMs (multimers 6-10), and high MWMs (>10 multimers) (see Fig. 2) [35]. Additionally a screening gel is used to assess the relative appearance (presence/absence, migration, and density) of individual multimer bands and subbands (triplet structure) when compared with that of NPP.…”

Preoperative Detection of Low Von Willebrand Factor Activity and Operative Blood Loss in Pediatric Scoliosis Patients Undergoing Posterior Spinal Fusion

“…Von Willebrand Factor (VWF) plays a critical dual role in primary hemostasis (platelet adhesion and plug formation), by binding to receptors on both platelets and endothelial cells, forming a vascular plug which serves as an adhesive bridge between the platelets and damaged sub endothelium at the site of vascular injury [1,2]. Von Willebrand disease (VWD), the most common inherited bleeding disorder, exhibits a heterogeneous inheritance pattern and phenotypic manifestations that starts in childhood with asubtle bleeding history [3][4][5].…”