Von Willebrand Disorder

Von Willebrand Disorder (VWD) is due to a deficiency of von Willebrand Factor (VWF). VWF a plasma factor that circulates in the blood attached to Factor VIII. The major function of VWF is to bind platelets, small cell fragments in the blood, to minor ruptures in blood vessels.

VWD is inherited but in a different manner to hemophilia. It affects women as often as men. The abnormal gene is not on the X chromosome (sex-related chromosome), but on the autosome (a regular chromosome, not a sex-related chromosome). A few people with severe VWD have two abnormal genes, one from each parent.

Most people with VWD have a mild-to-moderate form. In some families, VWD appears to be inherited as a dominant condition due to one abnormal gene from one parent (who may or may not have bleeding problems). However, in other families, VWD may be inherited as a recessive, with abnormal genes from both parents but no bleeding problems.

Both men and women with VWD often are frustrated because mild cases of the disorder may be difficult to diagnose. This is the most common bleeding disorder and affects an estimated 200,000 people in Australia, most of who are undiagnosed.

Von Willebrand disorder is mostly a genetic disorder. This means it is passed down through the genes from parent to child. The abnormal gene in von Willebrand disorder is on one of the regular chromosomes, not on one of the sex chromosomes (like haemophilia). This means that, unlike haemophilia which usually affects only males, von Willebrand disorder affects males and females in equal numbers.

In what is called the classical inheritance pattern, the von Willebrand disorder gene is usually dominant. This means a parent who has von Willebrand disorder has a 50% chance of passing a von Willebrand disorder gene along to each of his/her children. Types 1 and 2 von Willebrand disorder are usually inherited in this way.

In the less common inheritance pattern, two parents, each with von Willebrand disorder but without symptoms (called asymptomatic), may together have children who are severely affected by von Willebrand disorder. This form of inheritance is called “recessive”. Type 3 von Willebrand disorder is usually inherited in a recessive pattern. Many people carrying the von Willebrand disorder gene are asymptomatic which means they will not have bleeding symptoms, but they can still pass the disorder on to their children.

Most people with mild von Willebrand disorder will only experience a mild form of the condition and no medication will be required except when having surgery, and/or dental extractions. Far more serious bleeding may need to be treated with infusions (injections) of medications (synthetic hormones) or blood clotting products into a vein or sprays and tablets. People with von Willebrand disorder should not take aspirin in any form because it aggravates bleeding.

A: Hemophilia is an inherited condition and occurs in families. However in 1/3 of cases it appears in families with no previous history of the disorder. The gene causing Hemophilia is passed down from parent to child through generations. Men with Hemophilia will pass the gene on to their daughters but not their sons. Women who carry the gene causing Hemophilia can pass the gene on to their sons and daughters. Sons with the gene will have Hemophilia. Some women and girls who carry the gene may also experience bleeding problems.