What is Von Willebrand Disease?
Von Willebrand disease (VWD) is the most common inherited bleeding disorder, caused by a deficiency or dysfunction of von Willebrand factor (VWF), a large plasma glycoprotein essential for blood clotting. 1
Disease Mechanism
VWF serves two critical hemostatic functions that explain the bleeding manifestations when deficient or dysfunctional:
- Primary hemostasis: VWF mediates platelet adhesion and aggregation at vascular injury sites by binding to both exposed collagen and platelet glycoprotein Ibα 1
- Secondary hemostasis: VWF acts as a protective chaperone for factor VIII (FVIII) in circulation, preventing its premature degradation 1
Prevalence and Demographics
The epidemiologic data reveals an important distinction between laboratory prevalence and clinical disease:
- General population prevalence: Up to 1% based on epidemiologic studies 1
- Symptomatic prevalence: Approximately 1 in 1,000 (0.1%) 1
- Tertiary care center prevalence: 23 to 113 per million (approximately 1 in 10,000) 1
Both males and females are affected equally by inheritance, but females are diagnosed more frequently due to menstruation and childbirth challenges that unmask the bleeding tendency 1
Clinical Presentation
VWD manifests primarily as excessive mucocutaneous bleeding 1:
Common bleeding manifestations:
- Easy bruising
- Epistaxis (nosebleeds)
- Prolonged bleeding from minor wounds and oral cavity
- Heavy menstrual bleeding (menorrhagia)
- Prolonged bleeding after dental procedures, surgery, and childbirth
- Gastrointestinal bleeding
Severe cases may also present with:
- Musculoskeletal bleeding (hemarthrosis)
- Intramuscular hematomas 1
Classification System
VWD is classified into 3 main types based on whether the defect is quantitative or qualitative 1:
Type 1 VWD
- Partial quantitative deficiency of VWF
- Most common type
- VWF levels reduced but protein structure normal
Type 3 VWD
- Complete or near-complete absence of VWF
- Most severe form
- Quantitative deficiency
Type 2 VWD (Qualitative defects)
Subdivided into four subtypes based on specific functional abnormalities 1:
- Type 2A: Decreased platelet adhesion with loss of high molecular weight multimers (HMWM)
- Type 2B: Increased affinity for platelet GPIbα (gain-of-function mutation)
- Type 2M: Decreased platelet adhesion but normal multimer structure
- Type 2N: Decreased binding affinity for factor VIII
Type 1C
- A recently recognized subtype involving increased clearance of VWF from circulation 1
Diagnostic Criteria
Three established diagnostic criteria must be present for VWD diagnosis 1:
- Personal history of excessive mucocutaneous bleeding
- Family history of bleeding (autosomal inheritance pattern)
- Reduced VWF levels on laboratory testing
Historical Context
The disease was first described in 1926 by Finnish physician Erik von Willebrand, who documented a severe bleeding disorder in a family from the Åland islands. The index case was a young girl named Hjördis who died from bleeding during her fourth menstrual period. Von Willebrand initially called it "pseudohemophilia" because it resembled hemophilia but affected both sexes equally 1
Clinical Significance
Evidence-based clinical practice guidelines were developed in 2021 to provide diagnostic and management consensus, though challenges in achieving accurate and timely diagnosis persist 1. The disease remains globally underdiagnosed despite being the most common inherited bleeding disorder 2.