Rare Bleeding Disorders

Factor I Deficiency

Factor I is known as fibrinogen, a protein that helps form blood clots.1

A deficiency or dysfunction of factor I, or fibrinogen, is equally likely to affect men and women.1 There are several types of factor I disorders:

  • Afibrinogenemia occurs when fibrinogen is completely missing from the blood
  • Hypofibrinogenemia occurs when there are low levels of fibrinogen in the blood
  • Dysfibrinogenemia occurs when fibrinogen quantities are normal, but the fibrinogen is defective
  • Hypodysfibrinogenemia occurs when fibrinogen is low and does not function correctly

Afibrinogenemia (no fibrinogen) and hypofibrinogenemia (too little fibrinogen) have similar symptoms, including nosebleeds, easy bruising, heavy or long periods, bleeding at the umbilical cord, and heavy or prolonged bleeding after circumcision.1 Women with afibrinogenemia have an increased risk of problems during pregnancy, including miscarriage.1

People with dysfibrinogenemia (their fibrinogen that does not work properly) can be asymptomatic, but often experience bleeding problems similar to those with afibrinogenemia. In some cases, these people don’t bleed, but instead develop internal blood clots.1


The World Federation of Hemophilia calls plasma-derived fibrinogen concentrate, when available, the “ideal and safest” treatment for factor 1 deficiency.1 However, fibrinogen concentrate can be used to treat patients with congenital hypofibrinogenemia and afibrinogenemia but not dysfibrinogenemia. Fresh frozen plasma or cryoprecipitate are other treatments for Factor 1 deficiency, and both can be used in people with dysfibrinogenemia.2


  1. What Are Rare Clotting Factor Deficiencies? Montreal, QC: World Federation of Hemophilia; 2009.
  2. MASAC recommendations concerning products licensed for the treatment of hemophilia and other bleeding disorders (revised September 2014.) MASAC Document 230. National Hemophilia Foundation website. http://www.hemophilia.org/sites/default/files/document/files/230Text2014-09.pdf. Accessed December 18, 2014.