Factor Five Leiden

Possible Complications Associated With FVL

Research estimates that 3-5 white Americans out of every 100 are heterozygous for FVL. This would be those that inherited a single gene mutation from just one of their parents. Approximately one in every 1,000 are homozygous for FVL. That would mean that these people inherited two mutated genes, one from each parent. The FVL gene is dominant, which means that it exerts a ruling or controlling influence over the normal gene. Although if you are heterozygous, the normal gene will dilute the effect of the mutated gene. Those that are homozygous are than much more likely to have a venous thrombosis. If both of your genes are mutated than you would have no normal gene to dilute the effect. If you are African American than your inherited rate would be about 1.2%.

A person who is heterozygous for FVL has an increased risk of about 3-8 fold times greater, than a unaffected person, for developing a blood clot in the deep vein of your leg. These are called a DVT or deep vein thrombosis. Generally with those that are heterozygous you will see this happen due to external causes, such as pregnancy, birth control, hormone replacement therapy or with surgery. Usually this is how about 50% of people with FVL end up being diagnosed. After they develop their first venous thrombosis following one of these external causes.

People that are homozygous, two mutated genes, have a increased risk of clot formation up to 30-140-fold times greater than a person with normal FV genes. Homozygous people can develop a thrombosis from external causes also. However they can also develop a thrombosis with no external cause present at all, this is called a spontaneous thrombosis.

The presence of the FVL mutation associated with arterial blood clots can differ depending on which research material you read. Generally it is thought that FVL only affects the venous system, meaning that all blood clots would be found in a vein. Some research states that there has been no link found between FVL and an increased risk for myocardial infarction, a heart attack, or with strokes. Although, other material clearly states that there certainly could be an association with arterial thrombosis, especially in younger people who have other cardiovascular risk factors. [CONTINUED]