Basic Insights into the Molecular Etiology and Pathology of Von Willebrand Factor (VWF) Behind the ISTH And ECLM Classifications of Von Willebrand Disease Using a Complete Set of VWF Parameters

Review Article

Austin Hematol. 2019; 4(1): 1026.

Basic Insights into the Molecular Etiology and Pathology of Von Willebrand Factor (VWF) Behind the ISTH And ECLM Classifications of Von Willebrand Disease Using a Complete Set of VWF Parameterss

Michiels JJ1,2*, Smejkal P1, Penka M1, Blatny J3, Budde U4, Hermans C5, Batorova A6, Pricangova T6, Vangenechten I7 and Gadisseur A7

1Department of Clinical Hematology, University Hospital and Department of Laboratory Methods, Masaryk University, Czech Republic

2Goodheart Institute in Nature Medicine & Health, Blood Coagulation and Vascular Medicine Center, The Netherlands

3Department of Pediatric Hematology, Center for Thrombosis and Hemostasis, Children’s University Hospital, Czech Republic

4Central Laboratory, Germany

5Hemostasis and Thrombosis Center, St Luc University Hospital Brussels, Belgium

6Department of Hemostasis and Thrombosis National Hemophilia Center, Comenius University, Slovakia

7Hemostasis Research Unit, and Hematology Clinics, University Hospital Antwerp, Belgium

*Corresponding author: Jan Jacques Michiels, Goodheart Institute in Nature Medicine, Blood Coagulation and Vascular Medicine Center, Erasmus Tower Veenmos 13, 3069 AT, Rotterdam, The Netherlands

Received: October 18, 2019; Accepted: November 14, 2019; Published: November 21, 2019


The authors present a novel focus on the molecular basis of von Willebrand disease (VWD) phenotype classifications behind the International Society on Thrombosis and Haemostasis (ISTH) and the European Clinical Laboratory and Molecular (2019 ECLM). The ECLM molecular-based classification of VWD type 1, 2 and 3 in this study starts with the detection of the mutation defect located to the D1, D2, D”, D3, A1, A2, A3, D4, C1 to 6 or the CK domains of the VWF gene and than phenotyping each individual VWD patient by a complete set of FVIII:C and von Willebrand factor (VWF) parameters. Recessive VWD type 3 is caused by homozygous or double heterozygous null/null mutations and present with pseudo-hemophilia A first decribed by Erik von Willebrand. Recessive severe VWD type 1 due to homozygous or double heterozygous missense mutation in the D1 domain is featured by persistence of proVWF as the cause of secretion/multimerization and FVIII binding defect mimicking VWD type 3 (pseudo-hemophilia A). Carriers of heterozygous/wild type mutations in the D1 and D2 domains have decreased values for VWFpp, VWFpp/Ag ratios (0.51 to 0.99) indicating a secretion defect. ISTH defined VWD patients type 1 or 2 due to a multimerization defect in the D3 domain typically have VWF:RCo/Ag and VWF:CB/Ag ratios around the cut off level of 0.70 are diagnosed as VWD type 1E and type 2E patients when the ECLM criteria are applied. Twenty two reported VWD type 1E and 2E patients due to different missense mutations in the D3 domain are multimerization defects associated with an additional secretion defect (increased FVIII:C/VWF:Ag ratio) and/or clearance defect (increased VWFpp/Ag ratio). Ristocetine Induced Platelet Agglutination (RIPA) is decreased in VWD 2M, increased in VWD 2B , normal in VWD 1, normal in mild to moderate 2A, but decreased in pronounced VWD 2A, 2C and 2D. Dominant VWD 2A caused by mutations in the A2 domain have decreased VWF:RCo/Ag and VWF:CB/Ag ratios due to proteolytic loss of large VWF multimers. Dominant VWD 2B caused by gain of RIPA function mutations in A1 domain have decreased VWF:RCo/Ag and VWF:CB/Ag ratios due to spontaneous platelet-VWF interaction in vivo followed by proteolytic loss of large VWF multimers. Dominant VWD 1m caused by mutations in the A3 domain is featured by normal VWF:RCo/Ag ratio and decreased VWF:CB/ Ag ratio (2CB) or a decreased VWF:RCo/Ag ratio and normal VWF:CB/Ag (2M). The majority of VWF mutations in the D4 and C1 to C6 result in VWD phenotype 1 secretion defect (SD) with smeary (1sm) or normal (1m) multimers with normal clearance or a minor clearance defect. VWD type 1C (Vicenza) due to heterozygous R1205H/WT mutation in the D3 domain uniformally result in a prounounced FVIII/VWF clearance defect featured by a high VWFpp/Ag ratio and normal FVIII:C/VWF:Ag ratio. Heterozygous S2179F/WT mutation in the D4 domain is featured by pronounced VWD type 1m due to a Secretion Defect (SD) with increased FVIII:C/VWF:Ag ratio in combination with a Clearance (C) defect with increased VWF:pp/Ag ratio.

Keywords: Von Willebrand disease; Von Willebrand factor; ISTH criteria; ECLM classification; VWF gene mutation; Molecular biology; VWF domain; VWF assay; FVIII:C; Ristocetine cofactor; Platelet function analyzer PFA-100


We here present a novel focus on the molecular etiology and pathology of von Willebrand factor (VWF) protein behind the International Society of Thrombosis and Haemosiasis (ISTH) classification of von Willebrand disease related to mutation location in different domains of the VWF gene. The standard set of von Willebrand factor (VWF) parameters to diagnose and differentiate von Willebrand disease (VWD) type 1 from type 2 include Platelet Function Analyser Closure Time (PFA-CT), FVIII: coagulant activity (FVIII:C), VWF antigen (VWF:Ag), VWF ristocetine cofacor (VWF:RCo), VWF collagen binding (VWF:CB), FVIII binding to VWF (FVIII:BD), Ristocetine Induced Platelet Aggregation (RIPA), analysis of VWF multimers and the responses of FVIII:C and VWF parameters to DDAVP [1-4]. The original description of “Hereditary Pseudohemophilia A” by Erik von Willebrand appeared to be a recessive von Willebrand disease (VWD) type 3 caused by homozygous mutation P812rfs, 2680delC=null mutation in exon 18 [5].

Recessive VWD type 3 disease is caused by homozygous or double heterozygous null/null mutations distributed in any of the VWF gene domains and typically characterized by prolonged bleeding time and APTT, FVIII:C levels below 2%, undetectable VWF: Ag, VWF: RCo and VWF:CB and absence of Ristocetin Induced Platelet Aggregation (RIPA) [2,5-7]. VWD type 3 patients with virtual complete VWF deficiency are homozygous or compound heterozygous for two null alleles (gene deletions, stop codons, frame shift mutations, splice site mutations, and absence of mRNA) in the majority and rarely compound heterozygous for a null allele and a missence mutation or homozygous for a missence mutation. Reports on severe recessive VWD compound heterozygous for a null allele and a missense mutation and homozygous missense or double heterozygous for two missense mutations are associated with very low but measurable FVIII:C and VWF:Ag in particular after DDAVP and should be reclassified as severe recessive type 1 VWD [2,5-7]. Homozygous missense or compound missense/null mutations related to recessive severe type 1 VWD have been indentified in the VWF prosequence D1 and D2 domains, the D4, C1-6 (formerly B1-3, C1-2) and CK domains [6,7]. Missense mutations either homozygous, double heterozygous or associated with a null allele result in severe type 1 VWD caused by mutations restricted to the D1-D2 domains (D47H, S85P, Y87S, D141Y, D141N, C275S, W377C, I427N), to the D4, C1-6 (B1-3, C1-2) and CK domains (P2063S, C2174G, C2362F, N2546Y, C2671Y, C2754W, and C2804Y) [7]. Mild VWD type 1patients with ‘Low” VWF levels between 0.30 and 0.60 and PFA-CT values between the upper level of normal and 300 seconds are suspious for carrier state of VWF null or recessive or dominant heterozygous type 1 VWD due to single missense mutations in the D1, D2, D3, D4 and C1-6 domains [7]. Increased FVIII:C/VWF:Ag ratio is related to a Secretion Defect (SD) with restricted response of all VWF parameters to DDAVP. Decreased FVIII:C/VWF:Ag ratio below 0.5 and normal VWF:RCo/VWF:Ag ratios above 0.7 is typically seen in VWD type 2N [1-6]. VWD 2N is a mild hemophilia with normal PFA-CT and VWF function.

Classification of von Willebrand Disease 1980-2019

The classification of dominant VWD type 2 into 2A and 2B started in 1980 with the discovery of heightened interaction of Ristocetine Induced Platelet Aggregation (RIPA) and functional abnormal FVIII/ VWF protein in the presence of ristocetine in dominant VWD type IIB (2B), but decreased or absent in dominant VWD dominant IIA (2A) (Figures 1 and 2) [8-11]. Pronounced increase of degraded proteolytic band and triplet structure of each VWF band is the hall mark of VWD type 2A due to mutations (IIA in figures 1 and 2) in the A2 domain and caused by proteolysis of VWF at the VWF cleavage site (1605-1606 A2 domain) due to hypersensitivity of VWF to cleavage protease ADAMATS13 [12-14]. Proteolysis of VWF at the VWF cleavage is also seen to a less extend in normal subjects and in heterozygous Y1584C/WT type 1 VWD patients [9-11,15]. The RIPA gain of gain of function mutation in the A1 domain in VWD 2B results in spontaneous interaction of platelet GPIb-A1 VWF interactions in vivo followed by increased proteolysis of VWF at the VWF cleavage (1605-1606 A2 domain) with increase of proteolytic band and triplet structure of each VWF band similar as seen in VWD 2A [9-11,16]. The laboratory phenotypes of VWF parameters in VWD type 2A and 2B are similar characterized by prolonged BT, consistently low VWF:RCo/Ag and VWF:CBA/Ag ratios, absence of high and some of the intermediate VWF multimers with pronounced triple structure of individual VWF bands, and increased VWF degradation products (Figures 1 and 3) [6,9,10]. VWD 2B differs from 2A by increased RIPA in VWD 2B. RIPA is normal in mild and moderate VWD 2A and decreased in pronounced VWD 2A due to gain of RIPA function mutation in the A1 domain the mutated 2B VWF, which spontaneously interact with the platelet GPIb receptor followed by increased proteolysis at the VWF cleavage site 1605-1606 in the A2 domain [16]. Patients with severe VWD 2B respond to DDAVP with thrombocytopenia due to increased interaction of 2B mutated VWF protein and platelet GPIb receptor, which result in in vivo platelet aggregates and clumps followed by in vivo proteolysis of VWF at the VWF cleavage site in the A2 domain [16]. In 1980 Ruggeri et al., first described a recessive case of VWD IIC (2C) showing that the large multimers of von Willebrand factor in VWD 2C were lacking both from plasma and platelets due to a secretion multimerization defect of VWF from endothelial cells (Figure 1). The large VWF multimers did not appear in the circulation after infusion of DDAVP (1-Deamino- 8-D-arginine-Vasopressin) [17]. Mannucci et al nicely confirmed the existence of recessive VWD IIC VWD 2C patients showing the absence of large VWF multimers lacking the triplet structure [18].