Prothrombin deficiency is a bleeding disorder that slows the blood clotting process. People with this condition often experience prolonged bleeding following an injury, surgery, or having a tooth pulled. In severe cases of prothrombin deficiency, heavy bleeding occurs after minor trauma or even in the absence of injury (spontaneous bleeding). Women with prothrombin deficiency can have prolonged and sometimes abnormally heavy menstrual bleeding. Serious complications can result from bleeding into the joints, muscles, brain, or other internal organs. Milder forms of prothrombin deficiency do not involve spontaneous bleeding, and the condition may only become apparent following surgery or a serious injury.

Prothrombin deficiency is very rare; it is estimated to affect 1 in 2 million people in the general population.

Mutations in the F2 gene cause prothrombin deficiency. The F2 gene provides instructions for making the prothrombin protein (also called coagulation factor II), which plays a critical role in the formation of blood clots in response to injury. Prothrombin is the precursor to thrombin, a protein that initiates a series of chemical reactions to form a blood clot. After an injury, clots protect the body by sealing off damaged blood vessels and preventing further blood loss.

F2 gene mutations reduce the production of prothrombin in cells, which prevents clots from forming properly in response to injury. Problems with blood clotting can lead to excessive bleeding. Some mutations drastically reduce the activity of prothrombin and can lead to severe bleeding episodes. Other F2 gene mutations allow for a moderate amount of prothrombin activity, typically resulting in mild bleeding episodes.

Genetic Testing Information

• Genetic Testing Registry: Congenital prothrombin deficiency

Genetic and Rare Diseases Information Center

• Congenital factor II deficiency

Patient Support and Advocacy Resources

• National Organization for Rare Disorders (NORD)

Clinical Trials

• ClinicalTrials.gov

Catalog of Genes and Diseases from OMIM

• PROTHROMBIN DEFICIENCY, CONGENITAL

Scientific Articles on PubMed

• PubMed

• Akhavan S, Mannucci PM, Lak M, Mancuso G, Mazzucconi MG, Rocino A, Jenkins PV, Perkins SJ. Identification and three-dimensional structural analysis of nine novel mutations in patients with prothrombin deficiency. Thromb Haemost. 2000 Dec;84(6):989-97. Citation on PubMed
• Jayandharan G, Viswabandya A, Baidya S, Nair SC, Shaji RV, Chandy M, Srivastava A. Molecular genetics of hereditary prothrombin deficiency in Indian patients: identification of a novel Ala362 --> Thr (Prothrombin Vellore 1) mutation. J Thromb Haemost. 2005 Jul;3(7):1446-53. doi: 10.1111/j.1538-7836.2005.01402.x. Citation on PubMed
• Lefkowitz JB, Weller A, Nuss R, Santiago-Borrero PJ, Brown DL, Ortiz IR. A common mutation, Arg457-->Gln, links prothrombin deficiencies in the Puerto Rican population. J Thromb Haemost. 2003 Nov;1(11):2381-8. doi: 10.1046/j.1538-7836.2003.00420.x. Citation on PubMed
• Wong AY, Hewitt J, Clarke BJ, Hudson DM, Krisinger MJ, Dower NA, MacGillivray RT. Severe prothrombin deficiency caused by prothrombin-Edmonton (R-4Q) combined with a previously undetected deletion. J Thromb Haemost. 2006 Dec;4(12):2623-8. doi: 10.1111/j.1538-7836.2006.02235.x. Epub 2006 Sep 26. Citation on PubMed