Factor V deficiency

No. Hereditary factor V deficiency affects about 1 in 1 million people (with 10x higher rates in Iran and southern India) and is caused by mutations in the F5 gene.^[1]  Factor V deficiency can also be acquired. Acquired factor V deficiency is estimated to be even rarer, affecting 0.09 to 0.29 per million person years.^[1] Acquired factor V deficiency may occur in association with exposure to bovine thrombin preparations, an underlying cancer, infection, liver disease, or autoimmune-type disease, or in association with surgical procedures or antibiotic treatment.^[1] In around 20% of cases, no cause/association is found.^[2]

Signs and symptoms of hereditary factor V deficiency and acquired factor V deficiency range from no symptoms to severe bleeding problems. While diagnostic testing to diagnose factor V deficiency is quite simple, it is not currently possible to predict if a person's symptoms will be mild or severe.^[2]

Hereditary factor V deficiency is caused by inheriting two copies of the F5 gene mutation. Each sibling of a person with hereditary factor V deficiency has a 1 in 4 chance of also inheriting two F5 gene mutations. People with two F5 gene mutations typically have factor V levels below 10 to 15% of normal. Signs and symptoms range from no bleeding to severe bleeding problems (nose and oral bleeding are the most commonly reported symptoms, as well as heavy periods for affected females). These symptoms can often be managed with antifibrinolytic drugs, (treatments such as oral contraceptives and progestin containing intrauterine devices can help manage heavy periods). Major bleeding episodes are also possible, and are typically treated with IV fresh frozen plasma (to bring factor V levels above 20%).^[2]

Each sibling of a person with factor V deficiency also has a 1 in 2 chance or 50% chance of inheriting only one F5 gene mutation. People with one mutation tend to have factor V levels above 15%. People with one mutation often have no symptoms, but may have mild bleeding problems.^[2]