Factor V Leiden thrombophilia is a common genetic condition that makes a person more likely to form blood clots (thrombosis). It's the most frequently inherited cause of hypercoagulability, or an increased tendency for blood to clot. Factor V Leiden (FVL) results from a point mutation in the F5 gene, which encodes the factor V protein in the coagulation cascade. FVL renders factor V (both the activated and inactive forms) insensitive to the actions of activated protein C (aPC), a natural anticoagulant. People who have factor V Leiden get either one copy or, rarely, two copies of the changed gene from their parents. Having one copy of the changed gene slightly raises the risk of getting blood clots. Factor V (factor 5) is one of several special proteins in your blood that help it clot. They're called clotting factors. Once the bleeding stops, other proteins tell your clotting factors to. Factor V is an essential blood-clotting protein that plays a supporting but critical role in normal coagulation. It is also known as Proaccelerin or Labile Factor. When Factor V levels or activity are reduced, the clotting process becomes inefficient, and bleeding may last longer than expected. The gene for factor V is located on the first chromosome (1q24). It is genomically related to the family of multicopper oxidases, and is homologous to coagulation factor VIII. The gene spans 70 kb, consists of 25 exons, and the resulting protein has a relative molecular mass of approximately 330kDa. People with factor V Leiden thrombophilia have a higher than average risk of developing a type of blood clot called a deep venous thrombosis (DVT). DVTs occur most often in the legs, although they can also occur in other parts of the body, including the brain, eyes, liver, and kidneys. Factor V is a protein needed for blood to clot. Some people don't have the normal Factor V protein. Instead, they have an different form, factor V Leiden. We’ll be taking a deep dive into Factor V Leiden, exploring what it is, who is at risk, and how it can be treated. Our goal is to help demystify this condition and provide a comprehensive guide to living with Factor V Leiden. “Coagulation factor V” is the name of a protein that helps your blood clot when needed, like after an injury. Your F5 gene tells your body how to make this protein.