Factor V deficiency

Factor V (FV) deficiency was first described in a Norwegian patient in 1943 and reported by Dr. Paul Owren in 1947. Its incidence is about 1 in 1 million; fewer than 200 cases have been documented worldwide. It should not be confused with factor V Leiden, a clotting disorder.

The FV protein is a catalyst, accelerating the process by which prothrombin is converted to thrombin, the initial step in clot formation. FV deficiency is usually inherited in an autosomal recessive fashion, meaning both parents must carry the gene to pass it on to their children; it affects men and women equally.

Common characteristics of FV deficiency are bruising, bleeding under the skin, and nose, gum and mouth bleeds. Babies with severe FV deficiency are at increased risk of intracranial hemorrhage, or bleeding in the brain. People with severe FV deficiency can also experience bleeding in the lungs and gastrointestinal tract, which can be life threatening. Women frequently have menorrhagia, long, heavy periods.