What is the function of factor XI?

Factor XI (FXI) is the zymogen of a plasma protease, factor XIa (FXIa), that contributes to thrombin generation during blood coagulation by proteolytic activation of several coagulation factors, most notably factor IX (FIX).

What is factor 11 blood disorder?

Factor XI deficiency is a disorder that can cause abnormal bleeding due to a shortage (deficiency) of the factor XI protein, which is involved in blood clotting. This condition is classified as either partial or severe based on the degree of deficiency of the factor XI protein.

What factor activates factor XI?

Autoimmune Clotting Dysfunction Factor XI (FXI) is also a zymogen of the serine protease that is activated by FXII or thrombin, or autocatalytically. It is composed of four so-called apple domains in the heavy chain and a protease domain, and circulates as a homodimer.

What Is factor XI called?

Factor XI (FXI) deficiency, also called hemophilia C, plasma thromboplastin antecedent deficiency and Rosenthal syndrome, was first recognized in 1953 in patients who experienced severe bleeding after dental extractions. Its incidence is estimated at 1 in 100,000 in the general population.

What is normal factor XI levels?

Results are given in units per deciliter (U/dL). The normal range for factor XI activity levels is 65 to 130 U/dL, or 65% to 130%. If your results are lower than normal, it means you may have factor XI deficiency.

How do you test for Factor XI deficiency?

Screening coagulation tests that measure how long it takes the blood to clot include activated partial thromboplastin time (aPTT) and prothrombin time (PT). In individuals with deficiency of factor XI, the aPTT test will be prolonged (it will take the sample longer to clot than normal).

Is Factor 11 Deficiency an autoimmune disease?

Factor XI (FXI) is a plasma glycoprotein that acts during the contact phase of blood coagulation. Acquired FXI deficiency is related to autoimmune diseases, malignant tumors, and pregnancy [7–11].

What are the 3 types of hemophilia?

The three main forms of hemophilia include the following:

• Hemophilia A: Caused by a lack of the blood clotting factor VIII; approximately 85% of hemophiliacs have type A disease.
• Hemophilia B: Caused by a deficiency of factor IX.
• Hemophilia C: Some doctors use this term to refer to a lack of clotting factor XI.

How do you test for factor XI deficiency?

Why females are not affected by haemophilia?

“Growing up, we understood that men had hemophilia and women were “carriers.” Women passed along the X-linked gene, but did not actually get hemophilia because (it was believed) that the “good X chromosome” compensated for the X chromosome that carried hemophilia.

Can hemophiliacs get pregnant?

Before becoming pregnant, carriers need clear and accurate information about: The chances of the child having hemophilia (carrier women have a 50% chance of passing the disorder to their children). The consequences of inheriting hemophilia for both male and female children.

How is coagulation factor XI related to thrombosis?

Factor XI, a component of the intrinsic pathway of coagulation, contributes to the generation of thrombin, which is involved in both the formation of fibrin and protection against fibrinolysis. A deficiency of factor XI is associated with bleeding, but a role of high factor XI levels in thrombosis has not been investigated.

How is coagulation factor XI activated in vivo?

Factor XI is a component of the intrinsic pathway of coagulation. It can be activated in vitro by contact with a thrombogenic surface, such as glass. Whether surface contact contributes to the activation of factor XI in vivo, however, is uncertain.

How does factor X convert prothrombin to thrombin?

Factor VIIa and TF activate factor X to factor Xa, which in turn converts prothrombin to thrombin ( figure 3 ). The initial burst of thrombin is small, kept in check by tissue factor pathway inhibitor (TFPI).

How is the zymogen factor activated in thrombin?

The zymogen factor is activated into factor XIa by factor XIIa (FXIIa), thrombin, and FXIa itself; due to its activation by FXIIa, FXI is a member of the “contact pathway” (which includes HMWK, prekallikrein, factor XII, factor XI, and factor IX). Factor XIa activates factor IX by selectively cleaving arg-ala and arg-val peptide bonds.