Congenital afibrinogenemia is a bleeding disorder caused by impairment of the blood clotting process. Normally, blood clots protect the body after an injury by sealing off damaged blood vessels and preventing further blood loss. However, bleeding is uncontrolled in people with congenital afibrinogenemia. Newborns with this condition often experience prolonged bleeding from the umbilical cord stump after birth. Nosebleeds (epistaxis) and bleeding from the gums or tongue are common and can occur after minor trauma or in the absence of injury (spontaneous bleeding). Some affected individuals experience bleeding into the spaces between joints (hemarthrosis) or the muscles (hematoma). Rarely, bleeding in the brain or other internal organs occurs, which can be fatal. Women with congenital afibrinogenemia can have abnormally heavy menstrual bleeding (menorrhagia). Without proper treatment, women with this disorder may have difficulty carrying a pregnancy to term, resulting in repeated miscarriages.

Congenital afibrinogenemia is a rare condition that occurs in approximately 1 in 1 million newborns.

Congenital afibrinogenemia results from mutations in one of three genes, FGA, FGB, or FGG. Each of these genes provides instructions for making one part (subunit) of a protein called fibrinogen. This protein is important for blood clot formation (coagulation), which is needed to stop excessive bleeding after injury. In response to injury, fibrinogen is converted to fibrin, the main protein in blood clots. Fibrin proteins attach to each other, forming a stable network that makes up the blood clot.

Congenital afibrinogenemia is caused by a complete absence of fibrinogen protein. Most FGA, FGB, and FGG gene mutations that cause this condition result in a premature stop signal in the instructions for making the respective protein. If any protein is made, it is nonfunctional. When any one subunit is missing, the fibrinogen protein is not assembled, which results in the absence of fibrin. Consequently, blood clots do not form in response to injury, leading to the excessive bleeding seen in people with congenital afibrinogenemia.

Genetic Testing Information

• Genetic Testing Registry: Hereditary factor I deficiency disease

Genetic and Rare Diseases Information Center

• Familial afibrinogenemia

Patient Support and Advocacy Resources

• National Organization for Rare Disorders (NORD)

Clinical Trials

• ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

• AFIBRINOGENEMIA, CONGENITAL

Scientific Articles on PubMed

• PubMed

• Casini A, Lukowski S, Quintard VL, Crutu A, Zak M, Regazzoni S, de Moerloose P, Neerman-Arbez M. FGB mutations leading to congenital quantitative fibrinogen deficiencies: an update and report of four novel mutations. Thromb Res. 2014 May;133(5):868-74. doi: 10.1016/j.thromres.2014.01.022. Epub 2014 Jan 25. Citation on PubMed
• de Moerloose P, Casini A, Neerman-Arbez M. Congenital fibrinogen disorders: an update. Semin Thromb Hemost. 2013 Sep;39(6):585-95. doi: 10.1055/s-0033-1349222. Epub 2013 Jul 12. Citation on PubMed
• Lak M, Keihani M, Elahi F, Peyvandi F, Mannucci PM. Bleeding and thrombosis in 55 patients with inherited afibrinogenaemia. Br J Haematol. 1999 Oct;107(1):204-6. doi: 10.1046/j.1365-2141.1999.01681.x. Citation on PubMed
• Neerman-Arbez M, de Moerloose P, Bridel C, Honsberger A, Schonborner A, Rossier C, Peerlinck K, Claeyssens S, Di Michele D, d'Oiron R, Dreyfus M, Laubriat-Bianchin M, Dieval J, Antonarakis SE, Morris MA. Mutations in the fibrinogen aalpha gene account for the majority of cases of congenital afibrinogenemia. Blood. 2000 Jul 1;96(1):149-52. Citation on PubMed
• Neerman-Arbez M, de Moerloose P, Honsberger A, Parlier G, Arnuti B, Biron C, Borg JY, Eber S, Meili E, Peter-Salonen K, Ripoll L, Vervel C, d'Oiron R, Staeger P, Antonarakis SE, Morris MA. Molecular analysis of the fibrinogen gene cluster in 16 patients with congenital afibrinogenemia: novel truncating mutations in the FGA and FGG genes. Hum Genet. 2001 Mar;108(3):237-40. doi: 10.1007/s004390100469. Citation on PubMed
• Neerman-Arbez M, Honsberger A, Antonarakis SE, Morris MA. Deletion of the fibrinogen [correction of fibrogen] alpha-chain gene (FGA) causes congenital afibrogenemia. J Clin Invest. 1999 Jan;103(2):215-8. doi: 10.1172/JCI5471. Citation on PubMed or Free article on PubMed Central
• Neerman-Arbez M. Molecular basis of fibrinogen deficiency. Pathophysiol Haemost Thromb. 2006;35(1-2):187-98. doi: 10.1159/000093566. Citation on PubMed
• Weisel JW. Fibrinogen and fibrin. Adv Protein Chem. 2005;70:247-99. doi: 10.1016/S0065-3233(05)70008-5. Citation on PubMed