Factor XI deficiency is a blood clotting disorder which is also known as Hemophilia C, Plasma Thromboplastin Antecedent (PTA) Deficiency, or Rosenthal Syndrome.  

Factor XI or hemophilia C was only first recognized in 1953 and has an incidence of 1 in 100,000.  

The most frequent type of hemophilia is hemophilia A with an incidence of 1 in 5,000 and which is also known as factor VIII  deficiency or classic hemophilia.. Hemophilia B is the second most common type of hemophilia and is also known as factor IX deficiency, or Christmas disease with an incidence of 1 in 25,000.

Factor XI  deficiency is inherited in an autosomal dominant fashion, which means it affects men and women equally.  It can occur with greater frequency in people of Ashkenazi Jewish descent because intermarriage among this group has been more prevalent.  In Israel, factor XI deficiency has been estimated to be around 8% among Ashkenazi Jews, making it one of the most common genetic disorders in this group.  hemophilia. There is a wide variance in symptoms with mild, moderate and severe cases. The disorder was first recognized in 1953 by RL Rosenthal.

Factor XI deficiency is often referred to as Rosenthal syndrome.

Who is at Risk?
About 8% of the Ashkenazi Jewish population in Israel suffers from Factor XI deficiency. The Ashkenazi Jewish population across the world is in the highest risk group, but the deficiency is not contained in this population.

Symptoms
Unlike hemophilia, patients with Factor XI deficiency rarely bleed out spontaneously. The disorder is most commonly recognized after trauma or during surgery when clots do not form fast enough to stop bleeding effectively. Symptoms of Factor XI deficiency include:

• Increased bruising
• Prolonged bleeding
• Blood in urine
• Frequent nosebleeds
• Increased bleeding during menstruation

Complications
The immediate concern when patients suffer from a clotting disorder is stopping bleeding. Patients with severe cases of Factor XI deficiency may bleed out causing premature death. Complications typically occur during surgery or after trauma. Women are at higher risk of complications during vaginal childbirth or C-section.

Diagnosis
A blood test is required to diagnose Factor XI deficiency. Diagnosis typically occurs after patients present with symptoms of uncontrolled bleeding. A procedure as simple as a tooth extract may cause excessive bleeding leading to diagnosis.

Treatment
Patients do not typically require on-going treatment for Factor XI deficiency. Planned surgical procedures require treatment with plasma containing Factor XI. Fresh or frozen plasma may be used. Treatment may be required for multiple days following surgery or trauma. For instance, after vaginal childbirth, women with Factor XI deficiency may need plasma treatment for up to five days. C-sections require longer treatment, typically seven to 10 days.

Amicar and Cyklokapron are two medications commonly used to treat Factor XI deficiency. Both drugs inhibit fibrinolysis.

Life Expectancy
With proper diagnosis and treatment, patients with Factor XI deficiency can live a normal life. If patients are not properly treated with plasma containing Factor XI, death can occur. In some cases, patients have developed Hepatitis C after receiving plasma infusions. In these cases, life expectancy depends on the effects of Hepatitis C not Factor XI.