Key links
Follow us on Social media
Contact us

Jnetics, PO Box 65520, London N3 9BU

Email: .(JavaScript must be enabled to view this email address)

Tel: 020 8123 5022


Factor XI Deficiency

Factor XI deficiency (also known as PTA deficiency) is a bleeding disorder characterised by easy bruising, and abnormal bleeding after dental work, surgery, and injury. In women it can also cause heavy or prolonged bleeding during menstrual periods and after childbirth. Although symptoms vary widely, the condition is usually mild and can be treated effectively.

If you have just received a diagnosis there is help and support available - please see ‘Further information and support’ below for links to valuable resources. It is also important to note that not every person with this condition experiences all the symptoms described and it is worth talking to your doctor or other relevant healthcare specialists to discuss you or your family member’s individual case.


Factor XI deficiency is an autosomal condition that is partially dominant. This means that a person
can show symptoms even when they inherit only one abnormal Factor XI gene, however, they are
likely to be affected more if they inherit two abnormal Factor XI genes, one from each parent.


Estimates suggest that approximately 1 in 12 Ashkenazi Jews carry one abnormal Factor XI gene, whereas the condition is found in approximately 1 in 10,000 people in the general population.  Factor XI deficiency is also found to be more common in Iraqi Jews relative to the general population.


Presentation of Factor XI deficiency varies widely, even among family members. Symptoms are usually mild, with little or no bleeding, however in a few cases, the impact can be more severe.

People with Factor XI deficiency may experience:

  • Easy bruising or nosebleeds
  • Abnormal bleeding after dental work, surgery, or injury
  • Heavy or prolonged menstrual periods and/or after childbirth (in women)

Unlike in Haemophilia A and B, bleeding in joints and muscles is uncommon in Factor XI deficiency.

Please click on the titles to open and close the following information sections.

Factor XI deficiency is caused by either a lack of, or defect in, a protein in the blood called factor XI that contributes to the process of blood clotting (coagulation). It may be inheritable as a result of a defective gene located on chromosome 4 or acquired in association with other conditions such as liver disease.

There are various effective treatments available, including use of antifibrinolytic drugs that prevent the breakdown of blood clots and speed up the recovery from bleeds, plasma-derived Factor XI concentrates, recombinant Factor VIIa concentrates or fresh frozen plasma (FFP).

For many individuals with Factor XI deficiency, symptoms are so mild that treatment is not needed.

Factor XI deficiency is not a progressive disorder and does not typically affect lifespan. Many individuals do not show symptoms until they have some form of surgery or injury so often diagnosis is not made until late childhood or adulthood.

The disorder can be diagnosed clinically by a doctor familiar with the symptoms and laboratory tests that measure Factor XI levels in the blood.

Genetic testing via a simple blood test is also available and can identify over 99% of the disorder causing mutations in Ashkenazi Jews. In other populations the mutations causing Factor XI deficiency are more varied.

For more details about testing, please refer to the testing section.

For further information and support:

The Haemophilia Society

The Society is the only national and independent organisation for all people affected by bleeding disorders. It provides information and support for all people affected by bleeding disorders, including Factor XI deficiency, and represents their interests.

Tel: 020 7831 1020
Freephone: 0800 018 6068

Haemophilia Society Facebook Page

A facebook page for the Haemophilia Society which includes support resources.

The United Kingdom Haemophilia Centre Doctors’ Organisation

The UKHCDO is an association of medical practitioners who work within the Haemophilia Centres of England, Scotland, Northern Ireland or Wales. This link provides contact information for all the different NHS Haemophilia centres across the UK.

Circumcision London

Dr Martin Harris is a circumcision surgeon and a mohel with knowledge and experience of carrying out circumcisions in families with Factor XI deficiency. In collaboration with the Royal Free centre he was involved in developing a protocol for the management of circumcision on the male infants of Factor XI deficient patients.

Telephone: 020 8209 2401

To find out more about general resources relevant to Jewish genetic disorders, please visit our resources and support section.


Written by Jnetics.
Approved by Dr Keith Gomez, Consultant Haematologist, Royal Free Hospital
Last review: 7.1.2015