What Is Factor XII Deficiency?
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Factor XII Deficiency: Causes, Symptoms, and Treatment

Published on May 19, 2023 and last reviewed on May 24, 2023   -  5 min read


A hereditary condition called factor XII deficiency results in prolonged blood clotting in a test tube but not in persistent clinical bleeding tendencies.


John Hageman was the first person with factor XII (FXII) insufficiency, commonly known as Hageman factor deficiency, which was discovered in 1955. One in one million people are thought to experience it. Men and women are equally affected by FXII deficiency, which is transmitted in an autosomal recessive manner, meaning both parents must possess the gene. Asians are more likely to have it than those from other ethnic groups. Factor XII is necessary to create thrombin, a protein that changes fibrinogen into fibrin, which binds platelets and aids in holding a clot in place, FXII interacts with the activation of FXI to FXIa.

Blood tests that evaluate the levels of factor XII in the blood are often used to diagnose factor XII deficiency. Infusions of clotting factors, such as fresh frozen plasma or cryoprecipitate, may be used as a treatment option to stop bleeding episodes. A person's life expectancy or quality of life are often not adversely impacted by factor XII deficiency.

What Is Factor XII Deficiency?

Hageman factor deficiency is a rare genetic condition in which a person lacks all or almost all of the factor XII protein. Specialized proteins called clotting factors are necessary for effective clotting, the process by which blood clumps together to seal a wound's site and control bleeding. Factor XII is assumed to be necessary for healthy blood clotting, but when it is lacking, other blood clotting factors seem to step in to fill the deficit. The condition is therefore considered benign and typically exhibits no symptoms (is asymptomatic), and it is typically only discovered accidentally.

What Are the Causes of Factor XII Deficiency?

A mutation in the F12 gene, which is in charge of directing the production of the Factor XII protein, results in Factor XII deficiency. The blood clotting mechanism is weakened in people with factor XII deficiency, which can increase the risk of bleeding or bruising.

A person with factor XII deficiency must inherit two copies of the mutant F12 gene, one from each parent, in order to have the condition because it is an autosomal recessive trait. Carriers of the condition are individuals who have only one copy of the faulty gene and are normally asymptomatic. Men and women are equally affected by the illness, and anyone from any ethnic background might develop it.

It is crucial to remember that factor XII insufficiency is a hereditary illness and cannot be brought on by environmental or lifestyle factors.

What Are the Symptoms of Factor XII Deficiency?

Factor XII deficiency symptoms might differ from person to person and can be moderate to severe. While some people with factor XII deficiency might not show any symptoms, others might have a higher risk of bleeding or bruising, especially after an operation or accident. The degree of insufficiency is not necessarily correlated with the intensity of the symptoms. The following are some typical signs of factor XII deficiency:

  1. Excessive bleeding or bruising, especially following surgery or an injury.

  2. Persistent bleeding following dental operations or small wounds.

  3. Nosebleeds.

  4. Blood in the feces or urine.

  5. Heavy bleeding during a woman's period.

  6. Simple bruising.

How Is the Diagnosis of Factor XII Done?

Factor XII deficiency is usually diagnosed through blood tests that measure the levels of factor XII in the blood. The most common test used to diagnose factor XII deficiency is a clotting time test, which measures the time it takes for blood to clot in a test tube. If the clotting time is prolonged, it may suggest a deficiency in factor XII. Other tests that may be used to diagnose factor XII deficiency include:

  1. Activated Partial Thromboplastin Time (aPTT) Test: This test measures the time it takes for blood to clot and is used to evaluate the intrinsic pathway of coagulation, which is the pathway that factor XII is involved in. Individuals with factor XII deficiency may have a prolonged aPTT time.

  2. Factor XII Antigen Level Test: This test measures the amount of factor XII protein in the blood.

  3. Genetic Testing: This test can be used to identify mutations in the F12 gene that cause factor XII deficiency.

  4. Thrombin Time: This test evaluates the amount of time needed for fibrinogen to change into fibrin and can be used to spot problems with the clotting process' last step.

  5. Mixing Studies: These tests mix the patient's blood with healthy blood to check for clotting factor deficiencies.

How Is Treatment for Factor XII Deficiency Done?

Although there is no known therapy for factor XII deficiency, there are ways to control the symptoms of bleeding and avert its consequences. Depending on the degree of the deficit and the individual's particular needs, there may be a range of treatment alternatives. The following are some typical therapies for factor XII deficiency:

  1. Fresh Frozen Plasma: This procedure includes injecting healthy donor plasma, which has the clotting elements required for proper blood coagulation, into the patient. In people with factor XII deficiency, fresh frozen plasma is frequently used to control bleeding episodes.

  2. Cryoprecipitate: This procedure includes injecting a concentrated plasma solution that is highly concentrated in clotting factors, such as factor XII. When people with severe factor XII insufficiency are bleeding heavily, cryoprecipitate is frequently administered.

  3. Desmopressin: Used sometimes to control bleeding episodes in people with moderate factor XII insufficiency, this drug can raise blood levels of clotting factors.

  4. Tranexamic Acid: People with factor XII deficiency may use this drug to control bleeding episodes and prevent the dissolution of blood clots.

  5. Avoiding Drugs That May Impact Blood Clotting: People with factor XII deficiency may need to avoid or be closely watched while taking certain medications, such as Aspirin and blood thinners, since they may alter blood clotting.

  6. Antifibrinolytic Drugs: These drugs, which stop blood clots from dissolving, can be used to control bleeding episodes in people with factor XII deficiency.

Together with these therapies, people with factor XII deficiency might also need to take measures to minimize bleeding and damage. For example, they might need to avoid contact sports or use additional care when having surgery or getting their teeth pulled. It is crucial for people with factor XII deficiency to collaborate closely with their healthcare practitioner to create a thorough treatment plan that caters to their unique requirements.

How Is the Outlook (Prognosis) of Factor XII Deficiency?

A positive result is anticipated without therapy.

What Are the Complications of Factor XII Deficiency?

There are often no issues.

How Can It Be Prevented?

This condition is hereditary. There is currently no known way to stop it.


The blood clotting mechanism is disrupted by factor XII deficiency, a rare genetic condition. Although there is no known therapy for the illness, there are ways to manage bleeding episodes and avoid problems. The best course of action should be discussed with a healthcare provider if a person feels they may have a factor XII deficiency.

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Last reviewed at:
24 May 2023  -  5 min read




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