The Hemophilia and Thrombosis Center of Nevada

2020 W. Palomino Lane Suite 110

Las Vegas, Nevada 89106

702-385-2702

since May 5, 2008

Last updated May 5, 2008

webmaster RIS

What Is It??    FACTOR V LEIDEN

The discovery of Factor V Leiden was a major advance in the diagnosis of persons predisposed to the development of blood clots.  This is a common inherited abnormality in the Factor V protein which is important in clotting.  It is named after the city in the Netherlands that it was first identified in.

How Do You Get It??

Factor V Leiden is the most common inherited blood abnormality that results in the development of blood clots.  Because it is inherited, it is important that family members of affected persons be identified and tested.

What Should You Do About It??

Persons who are found to have this abnormality but have not had any history of blood clots should receive preventative measures during times when there is a greater risk of developing blood clots.  Because there is an increased risk of the development of blood clots in women with high hormone levels, those using birth control pills, pregnant, or on hormone replacement therapy may be at even greater risk for developing complications.  

Who Knows If They Have It??

Because this diagnosis is made on a blood sample where the clotting time is short following the addition of activated protein C, this test is called the Activated Protein C resistance (APC-R).  It requires a sample of blood to be sent for analysis to a specialized coagulation laboratory.  Since the end point of the test is clotting, it may be inaccurate in persons on blood thinners or with bleeding abnormalities.

The diagnosis may be confirmed on a genetic level.  This method identifies whether one or two genes were inherited.  Persons that have inherited the abnormality from both their parents (two genes or the homozygous state) are at a much greater risk of developing blood clots.  These clots can occur in the veins of the extremities (deep vein thrombosis) or lung (pulmonary embolism).

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Last modified: March 02, 2008