Von Willebrand Disease (VWD) is the most common inherited bleeding condition, but its prevalence is complex. The disorder affects the body’s ability to form clots, leading to excessive or prolonged bleeding. While genetic estimates suggest high prevalence, the number of diagnosed cases remains low. This disparity means the condition is genetically common yet clinically appears uncommon, often leading to significant underdiagnosis.
Defining Von Willebrand Disease and Its Causes
Von Willebrand Disease is a genetic disorder caused by a defect or deficiency in the von Willebrand Factor (VWF) blood protein. VWF plays two roles in blood clotting. First, it acts as an adhesive, helping platelets stick to the site of injury on a blood vessel wall to form a temporary plug.
Second, the protein serves as a protective carrier for Factor VIII, a clotting protein, extending its half-life in the bloodstream. When VWF is missing, reduced, or dysfunctional, the clotting process is impaired, resulting in abnormal bleeding. The severity of the disorder relates directly to the specific type of VWF abnormality.
The three main types of VWD are classified based on the nature of the VWF problem. Type 1 is the most frequent, involving a low quantity of otherwise normally functioning VWF. Type 2 VWD involves a qualitative defect, meaning the body produces sufficient VWF, but the protein does not function correctly due to structural issues. Type 2 is further divided into four subtypes. Type 3 is the most severe and rarest form, characterized by a near-total absence of VWF and very low levels of Factor VIII.
The Reality of VWD Prevalence
VWD genetically affects up to one percent of the general population. However, the number of people with a formal diagnosis is dramatically lower, with estimates for clinically significant cases around 125 per million people.
This difference between genetic prevalence and confirmed diagnosis highlights the issue of underdiagnosis. Many cases, especially mild Type 1 VWD, present with subtle symptoms often dismissed as normal variations. Heavy menstrual bleeding (menorrhagia) is a common symptom in women with VWD but is frequently not recognized as a bleeding disorder by patients or healthcare providers.
Hundreds of thousands of individuals with symptomatic VWD may be undiagnosed. The perceived rarity in clinical practice results from mild cases going unrecognized until a major bleeding event occurs, such as during surgery or childbirth. The average delay between symptom onset and diagnosis, particularly for women, can be as long as sixteen years.
Recognizable Signs and Symptoms
The clinical manifestations of VWD are typically related to mucocutaneous bleeding, involving the mucous membranes and the skin. The severity of these symptoms varies widely.
Common signs of VWD include:
- Easy bruising, often with bruises that are larger than expected.
- Frequent or prolonged nosebleeds that are difficult to stop.
- Heavy or prolonged menstrual periods for women.
- Excessive bleeding following minor injuries.
- Excessive bleeding following dental extractions.
- Excessive bleeding following surgical procedures.
Management and Treatment Options
Treatment for VWD is tailored to the specific type, severity, and immediate needs of the patient, such as before surgery. For many people with Type 1 VWD and some with Type 2, the primary treatment is Desmopressin (DDAVP). This synthetic hormone works by causing the release of stored VWF from the lining of blood vessels, rapidly increasing its level in the bloodstream.
DDAVP can be administered intravenously or as a nasal spray. For those unresponsive to DDAVP, or for people with severe VWD types, treatment involves von Willebrand Factor replacement therapy. These therapies use concentrates that contain VWF, sometimes combined with Factor VIII, to directly replace the missing or defective protein in the blood.
Antifibrinolytic agents, such as tranexamic acid, are also used to manage bleeding, particularly for localized issues or heavy menstrual flow. These medications help stabilize the blood clot once formed, preventing its premature breakdown. Proactive management, including patient education and a personalized treatment plan, minimizes the risk of bleeding complications.