Coagulation

Hereditary bleeding disorders

von Willebrand disease and testing


Editorial Board Member: Kyle Annen, D.O.
Deputy Editor-in-Chief: Patricia Tsang, M.D., M.B.A.
Fatima Aldarweesh, M.D.

Last author update: 5 December 2022
Last staff update: 5 December 2022

Copyright: 2002-2023, PathologyOutlines.com, Inc.

PubMed Search: von Willebrand disease testing

Fatima Aldarweesh, M.D.
Page views in 2022: 882
Page views in 2023 to date: 90
Cite this page: Aldarweesh F. von Willebrand disease and testing. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/coagulationvonwillebranddisease.html. Accessed February 8th, 2023.
Definition / general
Essential features
  • Gene for von Willebrand factor (vWF) is located on chromosome 12
  • vWF is synthesized by endothelial cells and megakaryocytes
  • vWF is a large polypeptide that polymerizes to form multimers of up to 100 subunits
  • Roles in hemostasis:
    • Adheres to platelet plug and fibrin clot, both essential to hemostasis at site of endothelial injury, particularly in high flow vessels
      • vWF mediates platelet adhesion to endothelium and formation of platelet plug by serving as a bridge between them; binds to glycoprotein Ib (GPIb) on platelets surfaces and to exposed subendothelium at site of endothelial injury (Best Pract Res Clin Haematol 2001;14:257, Thromb Haemost 1998;79:456)
      • vWF supports fibrin clot by serving as protective carrier protein for factor VIII; without vWF, factor VIII has shorter half life and its plasma levels are lower
Diagrams / tables

Table 1: Clinical characteristics of vWD subtypes (Clin Appl Thromb Hemost 2017;23:900)
Condition Inheritance pattern Common mutation domain Defect Clinical presentation
Type 1 Autosomal dominant Throughout vWF gene (OMIM: Von Willebrand Disease, Type 1 [Accessed 3 August 2022]) Decreased concentration of functionally normal vWF Mild to moderate mucocutaneous bleeding
Type 2A Autosomal dominant (OMIM: Von Willebrand Disease, Type 2 [Accessed 3 August 2022]) A1, A2 Enhanced susceptibility to cleavage by ADAMTS13 Moderate to severe mucocutaneous bleeding
CK Impaired dimer assembly
D1, D2 Impaired multimer assembly
A1, A2, D3 Impaired secretion of vWF, with enhanced intracellular retention
Type 2B Autosomal dominant (OMIM: Von Willebrand Disease, Type 2 [Accessed 3 August 2022]) A1 Increased affinity of GPIb binding site on vWF for the GPIb receptor Moderate to severe mucocutaneous bleeding
Type 2M Autosomal dominant (OMIM: Von Willebrand Disease, Type 2 [Accessed 3 August 2022]) A1 Reduced affinity of GPIb╬▒ binding site on vWF for the GPIb receptor Moderate to severe mucocutaneous bleeding
A3 Reduced affinity of vWF for collagen
Type 2N Autosomal recessive (OMIM: Von Willebrand Disease, Type 2 [Accessed 3 August 2022]) D' - D3 Reduced affinity of vWF for FVIII Moderate to severe hemophilia-like bleeding
Type 3 Autosomal recessive (OMIM: Von Willebrand Disease, Type 3 [Accessed 3 August 2022]) Throughout vWF gene Null alleles result in virtual absence of vWF Severe mucocutaneous bleeding and hemophilia-like bleeding
Rare: D1 - D2 Impaired dimer formation and intracellular retention


Table 2: Laboratory characteristics of subtypes of vWD (Clin Appl Thromb Hemost 2017;23:900, Teruya: Management of Bleeding Patients, 2nd Edition, 2021)
Condition vWF antigen level (vWF:Ag) in % vWF activity (vWF:Act) in % vWF:Act / vWF:Ag Factor VIII (FVIII) Multimers
Type 1 < 30 < 30 > 0.7 Low, normal All low
Type 2A Mildly low Low < 0.7 Normal, mildly low Absent high and intermediate multimers
Type 2B Normal, low Low < 0.7 Normal, mildly low Absent high multimers
Type 2M Normal, low Low < 0.7 Normal, mildly low Normal
Type 2N Normal, low Normal, low > 0.7 Low Normal
Type 3 < 3 < 3 Not applicable Low Absent
Low vWF 30 - 50 Normal, low > 0.7 Normal Normal
Normal 50 - 200 50 - 200 > 0.7 Normal Normal
Clinical features
  • Symptoms are similar to a platelet function defect (epistaxis, easy bruising, bleeding, menorrhagia)
  • vWD can be due to deficient (quantitative) or defective (qualitative) vWF (see Table 1)
    • Type 1 (70 - 80% of vWD):
      • Most common, partial quantitative deficiency of vWF but normal function
      • Normal platelet count
      • Mildest form of disease
    • Type 2 (15 - 20%):
      • Qualitative deficiency of vWF, variable quantitative deficiency, heterogeneous clinical presentation
        • Type 2A:
          • Most common type 2 subtype
          • Relative reduction of intermediate and high molecular weight multimers due to in vivo proteolytic degradation or defective multimer assembly and secretion
          • Normal platelet count
        • Type 2B:
          • Hemostatic defect due to intermittent thrombocytopenia and qualitatively abnormal vWF, with increased binding of vWF to GPIb (platelet vWF receptor), causing faster clearing of vWF coated platelets from the bloodstream
          • Platelet count drops further during pregnancy, surgery, 1-deamino-8-D-arginine vasopressin (DDAVP) therapy
            • Rapid clearance of platelets can be a problem following DDAVP therapy in type 2B vWD; if a previous patient trial of DDAVP has not been performed, then it is unwise to use DDAVP in an urgent bleeding situation as the resulting thrombocytopenia often complicates the problem
          • Reduction of high molecular weight multimers but an increase in low molecular weight fragments
          • Reduced ristocetin cofactor but increased ristocetin induced platelet aggregation (RIPA) (Blood 2018;131:1292)
      • Type 2M:
        • Rare
        • Due to mutation that impairs vWF and GPIb binding
      • Type 2N:
        • Rare, sometimes referred to as the Normandy variant
        • Markedly reduced affinity of vWF for factor VIII, causes reduction of factor VIII level
        • Other vWF lab tests are normal
        • Often misdiagnosed as hemophilia A (X linked recessive) but males and females in type 2N are equally affected
    • Type 3:
      • Very rare, often associated with consanguinity
      • Most severe clinical bleeding
      • Homozygous patients have marked deficiencies of plasma vWF and factor VIII activity, no vWF in platelets and endothelial cells, no secondary transfusion response, no response to DDAVP
    • Platelet type or pseudo vWD:
      • Rare disorder of mutation in GP1BA gene (not vWF gene), causing increased binding of vWF to GPIb (platelet surface membrane glycoprotein 1b) with gain of function and similar clinical findings as type 2B
      • Loss of higher vWF multimers
      • Enhanced ristocetin induced platelet aggregation (RIPA)
      • Variable thrombocytopenia
Diagnosis
  • Preliminary testing is recommended as starting points; these include complete blood count (CBC), prothrombin time (PT) and activated partial thromboplastin time aPTT
  • Specific testing for diagnosis: vWF antigen level (vWF:Ag), vWF activity (vWF:Act), factor VIII level (FVIII:C) (see Table 2)
    • vWF:Ag
      • Determines the amount of vWF in plasma
      • Enzyme linked immunosorbent assay (ELISA) or latex immunoassay (LIA) (Can J Vet Res 2008;72:420)
      • Levels can increase with injury, infection or other acute phase reactant stimuli
      • Type O patients have lower vWF antigen levels compared with other blood types; although bleeding symptoms may depend on vWF antigen levels, regardless of ABO type (Blood 1987;69:1691)
    • vWF:Act
      • Mostly commonly accomplished by ristocetin cofactor activity assay (vWF:RCo)
      • Ristocetin is an antibiotic that mimics the subendothelium, causing immobilization of vWF and inducing GPIb binding
      • Determines the ability of ristocetin to agglutinate exogenous platelets in the presence of vWF
      • Aggregation of platelets implies linkage via fibrinogen and GPIIb / IIIa; ristocetin links platelets through vWF and GPIb; appropriate term is agglutination
      • Rate of agglutination is related to the concentration of functionally normal vWF
    • vWF:Act / vWF:Ag ratio
      • Ratio of vWF activity to vWF antigen level in plasma
      • < 0.7 is generally indicative of a qualitative vWD (Blood Adv 2021;5:280)
    • FVIII:C
      • Measures FVIII concentration in plasma
      • Usually a clot based assay such as aPTT, ability of plasma to shorten aPTT of FVIII deficient control plasma
  • Additional testing for subtype classification:
    • RIPA
      • Patient's platelets are mixed with standard concentrations of ristocetin and patient's plasma is added to cause platelet agglutination (measured by aggregometer)
      • Increased aggregation in type 2B vWD in response to low concentration of ristocetin due to GPIb mutation, which increases affinity for vWF
    • vWF collagen binding assay (vWF:CB)
    • vWF multimer analysis (see Molecular / cytogenetics images)
      • Detects the size distribution of multimers using radiolabeled or enzyme linked anti-vWF antibody
      • Involves separation of multimers by size using agarose gel electrophoresis of patient's plasma (Thromb Res 2010;126:543)
      • Normal in types 1, 2N or 2M (type 1 has reduced quantity of all sizes but difficult to identify on gel)
    • DDAVP challenge
      • Recommended in patients with mild to moderate types 1 and 2
      • vWF:Ag, vWF:Ag, FVIII:C are measured at standard intervals after DDAVP administration
      • Response is adequate if 2 - 4 fold increase in antigen and activity levels is observed and at least 30% increase in factor VIII level for at least 12 hours
      • May achieve hemostasis in type 1
      • Contraindicated in type 2B
    • Gene sequencing with mutation analysis
      • To detect mutations in the vWF gene
      • Not widely used due to genetic complexity and phenotypic variability
      • Can help subclassify type 2 vWD
  • Repeat testing is often recommended because vWF and factor VIII become elevated during minor illnesses, injury, stress, pregnancy, estrogen use, other acute phase reactions or in newborns
Case reports
Molecular / cytogenetics images

Images hosted on other servers:

vWF multimer analysis

Sample pathology report
  • History: A 14 year old girl presented to the emergency department with fatigue and heavy menses. She was referred to hematology for evaluation. Platelet count, PT/ INR and PTT are all within normal limits.
  • Results: The von Willebrand factor (vWF) antigen level is normal at 87% (normal adult range 55 - 200%). The vWF functional antibody (vWF GPIb binding activity) level is normal at 87% (normal adult range 50 - 155%). The vWF collagen binding activity is normal at 89% (normal adult range 46 - 159%). The ratio of each of the cofactor functional assays to von Willebrand antigen is normal. The factor VIII level is normal at 80% (normal range 57 - 152%). Blood group is A.
  • Conclusion: The current results provide no definitive evidence for von Willebrand disease.
Board review style question #1
A 17 year old girl with a history of von Willebrand disease (vWD) of unknown type is scheduled to undergo wisdom tooth extraction. The hematologist considered the 1-deamino-8-D-arginine vasopressin (DDAVP) challenge test. In which one of the following types of vWD has DDAVP been known to cause thrombocytopenia?

  1. Type 1
  2. Type 2A
  3. Type 2B
  4. Type 2N
  5. Type 3
Board review style answer #1
C. Type 2B. The von Willebrand factor (vWF) gain of function mutation increases platelet aggregation leading to thrombocytopenia.

Comment Here

Reference: von Willebrand disease and testing
Back to top
Image 01 Image 02