Related Experiment Video
Updated: Aug 16, 2026

Investigating von Willebrand Factor Pathophysiology Using a Flow Chamber Model of von Willebrand Factor-platelet String Formation
Published on: August 14, 2017
Determinants of bleeding severity in von Willebrand disease
1Department of Pediatrics, University of Iowa, 200 Hawkins Drive, Iowa City, IA 52242, USA. jorge-dipaola@uiowa.edu
Abstract:
von Willebrand disease (VWD) is one of the most common bleeding disorders. It is caused by abnormalities in the von Willebrand factor (VWF) protein, and is characterized by incomplete penetrance and variable expressivity. VWF levels vary widely in the population. The best-characterized human genetic modifier of VWF is the ABO blood group. Patients with VWD show considerable variation in bleeding tendency even within the same family, independently of VWF levels. It is possible that several modifier genes influence the phenotype. Variants of genes that encode for platelet receptors as well as those that encode for clotting factor levels have been proposed as modifiers. It is hoped that new clinical-genetic studies will shed light on these issues and help practitioners to determine the population at risk for bleeding.
Related Concept Videos
Disorders of Hemostasis
Thromboembolic Disorders
Two factors primarily cause thromboembolic conditions.
Formation of the Platelet Plug
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
Extrinsic and Intrinsic Pathways of Hemostasis
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which forms a...
Introduction to Hemostasis
The three phases of hemostasis involve many clotting factors present in plasma and several substances released by platelets and injured tissue cells. It is a fast, localized, and...
Anticoagulant Drugs: Low-Molecular-Weight Heparins
Esophageal Varices-II: Clinical Features and Management
In the initial assessment, a thorough review of the patient's medical history is vital to identify risk factors such as liver disease, alcohol abuse, or...

