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F8 gene

coagulation factor VIII

Normal Function

The F8 gene provides instructions for making a protein called coagulation factor VIII. Coagulation factors are a group of related proteins that are essential for the formation of blood clots. After an injury, clots protect the body by sealing off damaged blood vessels and preventing further blood loss.

Coagulation factor VIII is made chiefly by cells in the liver. This protein circulates in the bloodstream in an inactive form, bound to another molecule called von Willebrand factor, until an injury that damages blood vessels occurs. In response to injury, coagulation factor VIII is activated and separates from von Willebrand factor. The active protein (sometimes written as coagulation factor VIIIa) interacts with another coagulation factor called factor IX. This interaction sets off a chain of additional chemical reactions that form a blood clot.

Health Conditions Related to Genetic Changes


Mutations in the F8 gene cause hemophilia A, the most common form of this bleeding disorder. More than 1,300 alterations in this gene have been identified. Some of these mutations change single DNA building blocks (base pairs) in the gene, while others delete or insert multiple base pairs. The most common mutation in people with severe hemophilia A is a rearrangement of genetic material called an inversion. This inversion involves a large segment of the F8 gene.

Mutations in the F8 gene lead to the production of an abnormal version of coagulation factor VIII or reduce the amount of this protein. The altered or missing protein cannot participate effectively in the blood clotting process. As a result, blood clots cannot form properly in response to injury. These problems with blood clotting lead to excessive bleeding that can be difficult to control. Some mutations, such as the large inversion described above, almost completely eliminate the activity of coagulation factor VIII and result in severe hemophilia. Other mutations reduce but do not eliminate the protein's activity, resulting in mild or moderate hemophilia.

More About This Health Condition

Other Names for This Gene

  • AHF
  • antihemophilic factor
  • coagulation factor VIII, procoagulant component
  • coagulation factor VIII, procoagulant component (hemophilia A)
  • DXS1253E
  • Factor VIIIF8B
  • HEMA
  • procoagulant component

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Bicocchi MP, Pasino M, Lanza T, Bottini F, Boeri E, Mori PG, Molinari AC, Rosano C, Acquila M. Analysis of 18 novel mutations in the factor VIII gene. Br J Haematol. 2003 Sep;122(5):810-7. doi: 10.1046/j.1365-2141.2003.04494.x. Citation on PubMed
  • Bogdanova N, Markoff A, Eisert R, Wermes C, Pollmann H, Todorova A, Chlystun M, Nowak-Gottl U, Horst J. Spectrum of molecular defects and mutation detection rate in patients with mild and moderate hemophilia A. Hum Mutat. 2007 Jan;28(1):54-60. doi: 10.1002/humu.20403. Citation on PubMed
  • Bogdanova N, Markoff A, Pollmann H, Nowak-Gottl U, Eisert R, Wermes C, Todorova A, Eigel A, Dworniczak B, Horst J. Spectrum of molecular defects and mutation detection rate in patients with severe hemophilia A. Hum Mutat. 2005 Sep;26(3):249-54. doi: 10.1002/humu.20208. Citation on PubMed
  • Bolton-Maggs PH, Pasi KJ. Haemophilias A and B. Lancet. 2003 May 24;361(9371):1801-9. doi: 10.1016/S0140-6736(03)13405-8. Citation on PubMed
  • Bowen DJ. Haemophilia A and haemophilia B: molecular insights. Mol Pathol. 2002 Apr;55(2):127-44. doi: 10.1136/mp.55.2.127. Erratum In: Mol Pathol 2002 Jun;55(3):208. Citation on PubMed or Free article on PubMed Central
  • Graw J, Brackmann HH, Oldenburg J, Schneppenheim R, Spannagl M, Schwaab R. Haemophilia A: from mutation analysis to new therapies. Nat Rev Genet. 2005 Jun;6(6):488-501. doi: 10.1038/nrg1617. Citation on PubMed
  • Oldenburg J, El-Maarri O. New insight into the molecular basis of hemophilia A. Int J Hematol. 2006 Feb;83(2):96-102. doi: 10.1532/IJH97.06012. Citation on PubMed
  • Shen BW, Spiegel PC, Chang CH, Huh JW, Lee JS, Kim J, Kim YH, Stoddard BL. The tertiary structure and domain organization of coagulation factor VIII. Blood. 2008 Feb 1;111(3):1240-7. doi: 10.1182/blood-2007-08-109918. Epub 2007 Oct 26. Citation on PubMed or Free article on PubMed Central
  • Thompson AR. Structure and function of the factor VIII gene and protein. Semin Thromb Hemost. 2003 Feb;29(1):11-22. doi: 10.1055/s-2003-37935. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.