What is factor XI deficiency?

Updated: Oct 28, 2019
  • Author: Muhammad A Mir, MD, FACP; Chief Editor: Perumal Thiagarajan, MD  more...
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Answer

Factor XI deficiency is a congenital deficiency of blood coagulation factor XI (known as plasma thromboplastin antecedent [PTA] or antihemophilic factor C) resulting in a systemic blood-clotting defect called hemophilia C or Rosenthal syndrome, which may resemble classic hemophilia.

Factor XI is a key component of the intrinsic pathway of blood coagulation in vitro, but its exact role in vivo is uncertain. Factor XI is activated by thrombin and may participate in clot formation once coagulation has been initiated by other mechanisms. The risk of bleeding in factor XI deficiency depends on the severity of the deficiency. Additional coexisting abnormalities of hemostasis, such as von Willebrand disease, may also be responsible for variations in clinical presentation, particularly in individuals with mild factor XI deficiency. [105, 106]

Approximately 40-50% of all persons lacking factor XI are of Ashkenazi Jewish extraction. [107] Factor XI deficiency may be considered in patients evaluated for hemorrhage or unexplained, prolonged aPTT or through family or other genetic studies. Women with factor XI deficiency are prone to menorrhagia and to bleeding complications after childbirth. [108, 109] Individuals with factor XI deficiency need careful planning for elective surgery and dental extractions. Fresh frozen plasmafibrin glue, antifibrinolytic drugs, desmopressin, and factor XI concentrates have all been used successfully. Factor XI concentrate is usually reserved for younger patients with severe deficiency because its use in older patients has been associated with thrombotic phenomena.


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