Factor XI Deficiency

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.


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