Factor V Leiden

Factor V Leiden is a genetic condition that affects the blood's ability to clot properly. It involves a change in a protein called Factor V, which is important for blood clotting. This change makes the blood more likely to form clots in veins, which can block blood flow and cause problems like deep vein thrombosis or pulmonary embolism. The condition mainly affects the circulatory system and increases the risk of dangerous blood clots. People with this condition may not have symptoms until a clot forms. It is one of the most common inherited causes of abnormal blood clotting. Understanding this condition helps explain why some people have a higher risk of clotting disorders.

Factor V Leiden is a hereditary thrombophilia caused by a specific mutation in the F5 gene resulting in a single amino acid substitution (Arg506Gln) in the Factor V protein. This mutation renders Factor V resistant to inactivation by activated protein C, leading to a hypercoagulable state. The primary clinical significance is an increased risk of venous thromboembolism (VTE), including deep vein thrombosis and pulmonary embolism. It is the most common inherited cause of thrombophilia in Caucasians. Heterozygous carriers have a 3- to 8-fold increased risk of VTE, while homozygous individuals have a substantially higher risk. The mutation does not typically increase the risk of arterial thrombosis. Diagnosis is important for risk stratification and management of thrombotic events.