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HEMOPHILIA.ORG > BLEEDING DISORDERS INFO CENTER > TYPES >
FACTOR I DEFICIENCY


Factor I Deficiency
(Afibrinogenemia)

What Is It?
Fibrinogen, also known as factor I, is needed for most types of platelet aggregation. It's the last step in the clotting process—the "glue" that holds the clot together. People who have a factor I deficiency have a combined bleeding and clotting disorder, meaning that both platelets and clotting are abnormal. Since its discovery in 1920, there have only been about 200 cases of this disorder.

Included under factor I deficiency are several rare coagulation disorders known as congenital fibrinogen defects. They include:
• afibrinogenemia
• hypofibrinogenemia
• dysfibrinogenemia

The first two are called quantitative abnormalities because they have to do with an absent or low quantity of fibrinogen. The third is called a qualitative abnormality because the fibrinogen does not work well.

Afibrinogenemia is the complete absence of fibrinogen. Hypofibrinogenemia is a low level of fibrinogen—less than 100mg in 1dL of blood. Both conditions are inherited in an autosomal fashion and can affect males and females.

The severity of the disorder is related to the amount of fibrinogen. Afibrinogenemia is usually discovered in newborns and can cause bleeding from the umbilical cord, genitourinary tract or central nervous system. People with hypofibrinogenemia may have little, moderate or severe bleeding.

Dysfibrinogenemias are due to variations in the factor I molecule. More than 70 different types of dysfibrinogenemia have been identified.

Inheritance Pattern
The disorder is not sex-linked as is hemophilia. It affects both males and females with equal frequency. It is autosomal recessive, which means that if the clotting defect is inherited from a parent, the child will be a genetic carrier of the condition, but may or may not have symptoms.

Symptoms and Diagnosis
Few people who have any of these disorders suffer symptoms, although some are predisposed to form blood clots (thrombosis).

Treatments
Many people with hypofibrinogenemia or dysfibrinogenemia need no treatment. Those who require treatment may be given cryoprecipitate or fresh frozen plasma. Anticoagulants are sometimes prescribed to reduce the risk of thrombosis. The goal of treatment is to raise the patient's fibrinogen level to 100 mg/dL for minor bleeding and up to 200 mg/dL for surgery or severe bleeding. (One unit of fresh frozen plasma has about 450 mg of fibrinogen.)

Complications
Plasma levels of fibrinogen exceeding 1,000 mg/dL have been reported to possibly increase the risk of thrombosis. In women, menstrual bleeding can be a severe problem and must be controlled.

Disclaimer
The information contained on the NHF web site is provided for your general information only. NHF does not give medical advice or engage in the practice of medicine. NHF under no circumstances recommends particular treatment for specific individuals and in all cases recommends that you consult your physician or local treatment center before pursuing any course of treatment.
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