Factor XII Deficiency

Factor XII Deficiency

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Factor XII Deficiency is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • F12 deficiency
  • HAF deficiency
  • Hageman factor deficiency
  • Hageman trait

Disorder Subdivisions

  • None

General Discussion

Summary

Factor XII deficiency is a rare genetic blood disorder that causes prolonged clotting (coagulation) of blood in a test tube without the presence of prolonged clinical bleeding tendencies. It is caused by a deficiency of the factor XII (Hageman factor), a plasma protein (glycoprotein). Specifically, factor XII is a clotting factor. Clotting factors are specialized proteins that are essential for proper clotting, the process by which blood clumps together to plug the site of a wound to stop bleeding. Although it is thought that factor XII is needed for proper blood clotting, when it is deficient, other blood clotting factors appear to compensate for its absence. Therefore, the disorder is thought to be benign and usually presents no symptoms (asymptomatic); it is usually only accidentally discovered through pre-operative blood tests that are required by hospitals.



Introduction

Factor XII deficiency was first described in the medical literature in 1955 by doctors Oscar Ratnoff and Jane Colopy in a patient named John Hageman. The disorder is sometimes known as Hageman factor deficiency or Hageman trait.

Symptoms

Factor XII deficiency is rarely associated with any symptoms (asymptomatic). However, when blood from a patient is subjected to a partial thromboplastin time test (PTT), a test measuring clotting time, it takes an abnormally long time for the blood to clot. Serum prothrombin (PT) time, another test of blood clotting, is also abnormally long. The blood level of factor XII tends to vary greatly.



According to some older medical reports, factor XII deficiency may predispose affected individuals to developing blood clots (thrombi) at an early age. For example, individuals may have a greater risk than the general population in developing deep vein thrombosis or acquired thrombotic disorders. However, such an association remains unproven.



Researchers are now studying drugs to block (inhibit) factor XII as a potential therapy for individuals who are prone to developing blood clots. More research is necessary to determine the exact role that factor XII plays in the development or prevention of blood clots and its overall functions in the body.



There are also reports in the medical literature that suggest an association between factor XII deficiency and repeated unexplained miscarriages in some affected women. However, such an association remains controversial and unproven.

Causes

Factor XII deficiency is inherited as an autosomal recessive disorder. Genetic diseases are determined by two genes, one received from the father and one from the mother.



Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.



Investigators have determined that factor XII deficiency occurs due to mutations of the F12 gene located on the long arm of chromosome 5 (5q33-qter). Chromosomes, which are present in the nucleus of human cells, carry the genetic information for each individual. Pairs of human chromosomes are numbered from 1 through 22, and an additional 23rd pair of sex chromosomes which include one X and one Y chromosome in males and two X chromosomes in females. Each chromosome has a short arm designated "p" and a long arm designated "q". Chromosomes are further sub-divided into many bands that are numbered. For example, "chromosome 5q33" refers to band 33 on the long arm of chromosome 5. The numbered bands specify the location of the thousands of genes that are present on each chromosome.



The F12 gene creates (encodes) factor XII, which is a clotting factor. Mutations of the F12 gene lead to low levels of functional factor XII in the blood (potentially less than 1%). The exact role that factor XII plays in the clotting process and any additional effects it has on the body are not fully understood. In addition to the clotting process, factor XII is believed to play a role tissue repair and the formation of blood vessels (angiogenesis).

Affected Populations

Factor XII deficiency affects persons of Asian descent more often than individuals of other ethnicities. Males and females are affected in equal numbers. Since no symptoms are usually associated with factor XII deficiency, many individuals remain undiagnosed. The exact incidence of the disorder in the general population is unknown, but estimated to be approximately 1 in 1 million individuals.

Standard Therapies

Diagnosis

Factor XII deficiency is often diagnosed accidentally during a routine blood clotting (coagulation) tests as in one done before surgery. In affected individuals, it will take longer for their blood to clot during these tests. Further tests can reveal low levels of factor XII in the blood.



Clinical Testing and Work-up

A diagnosis of factor XII deficiency may be suspected in individuals without clinical signs or a previous history of a bleeding disorder in whom specialized tests called screening coagulation tests known as activated partial thromboplastin time (aPTT) or prothrombin time PT) are abnormal. These tests measure how long it takes the blood to clot.



Individuals with abnormal results on these tests but no bleeding symptoms may then be screened for a condition known as antiphospholipid syndrome. A test will be run to detect a specific inhibitor called lupus anticoagulant, which is present in individuals with acquired antiphospholipid syndrome and can cause similar abnormal results on the aPTT or PT tests.



A diagnosis of factor XII deficiency can be confirmed by a test called an assay. An assay is a test that measures the activity of coagulation factors. It can demonstrate a deficiency of factor XII.



Treatment

Treatment for this disorder is usually not necessary since bleeding abnormalities only mild or nonexistent.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.



For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:



Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov



For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

References

TEXTBOOKS

Colman RW. Factor XII Deficiency. NORD Guide to Rare Disorders. Lippincott Williams & Wilkins. Philadelphia, PA. 2003:382-383.



Bick RL. Disorders of Thrombosis & Hemostasis. 3rd ed. Lippincott Williams & Wilkins. Philadelphia, PA; 2002:126.



Hoffman R, et al., eds. Hematology Basic Principles and Practice, 2nd ed. New York, NY: Churchill-Livingstone, Inc; 1995:1581-83, 1699.



JOURNAL ARTICLES

Pham M, Stoll G, Nieswandt B, Bendszus M, Kleinschnitz C. Blood coagulation factor XII – a neglected player in stroke pathophysiology. J Mol Med (Berl). 2012;90:119-126. http://www.ncbi.nlm.nih.gov/pubmed/21909687



Muller F, Gailani D, Renne T. Factor XI and XII as antithrombotic targets. Curr Opin Hematol. 2011;18:349-355. http://www.ncbi.nlm.nih.gov/pubmed/21730835



Stayrou E, Schmaier AH. Factor XII: what does it contribute to our understanding of the physiology and pathophysiology of hemostasis & thrombosis. Thromb Res. 2010;125;210-215. http://www.ncbi.nlm.nih.gov/pubmed/20022081



Schmaier AH, Larusch G. Factor XII: a new life for an old protein. Thromb Haemost. 2010;104;915-918. http://www.ncbi.nlm.nih.gov/pubmed/20806112



Schmaier AH. The elusive physiologic role of factor XII. J Clin Invest. 2008;118:3006-3009. http://www.ncbi.nlm.nih.gov/pubmed/18725991



Matsubayashi H, Sugi T, Suzuki T, et al. Decreased factor XII activity is associated with recurrent IVF-ET failure. Am J Reprod Immunol. 2008;59:316-322. http://www.ncbi.nlm.nih.gov/pubmed/18294355



Colman RW. Are hemostasis and thrombosis two sides of the same coin? J Exp Med. 2006;20:493-495. http://www.ncbi.nlm.nih.gov/pubmed/16533890



Girolami A, Randi ML, Gavasso S, Lombardi AM, Spiezia F. The occasional venous thromboses seen in patients with severe (homozygous) FXII deficiency are probably due to associated risk factors: a study of prevalence in 21 patients and review of the literature. J Thromb Thrombolysis. 2004;17:139-143. http://www.ncbi.nlm.nih.gov/pubmed/15306750



Renne T, Pozgajova M, Gruner S, et al. Defective thrombus formation in mice lacking coagulation factor XII. J Exp Med. 2005;202:271-281. http://www.ncbi.nlm.nih.gov/pubmed/16009717



Matsuura T, Kobayashi T, Asahina T, Kanayama N, Terao T. Is factor XII deficiency related to recurrent miscarriage. Semin Thromb Hemost. 2001;27:115-20. http://www.ncbi.nlm.nih.gov/pubmed/11372764



INTERNET

McKusick VA., ed. Online Mendelian Inheritance in Man (OMIM). Baltimore. MD: The Johns Hopkins University; Entry No:234000; Last Update:11/28/2006. Available at: http://omim.org/entry/234000 Accessed on: April 20, 2012.



Canadian Hemophilia Society. Factor XII Deficiency. 2004. Available at: http://www.hemophilia.ca/en/bleeding-disorders/other-factor-deficiencies/factor-xii-deficiency/ Accessed On: April 20, 2012.

Resources

National Hemophilia Foundation

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New York, NY 10001

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Tel: (212)328-3700

Fax: (212)328-3777

Tel: (800)424-2634

Email: handi@hemophilia.org

Internet: http://www.hemophilia.org



Canadian Hemophilia Society

400-1255 University Street

Montreal

Quebec, H3B 3B6

Canada

Tel: 5148480503

Fax: 5148489661

Tel: 8006682686

Email: chs@hemophilia.ca

Internet: http://www.hemophilia.ca



NIH/National Heart, Lung and Blood Institute

P.O. Box 30105

Bethesda, MD 20892-0105

Tel: (301)592-8573

Fax: (301)251-1223

Email: nhlbiinfo@rover.nhlbi.nih.gov

Internet: http://www.nhlbi.nih.gov/



World Federation of Hemophilia

1425 René Lévesque Blvd. W. Suite 1010

Montreal

Quebec, H3G 1T7

Canada

Tel: 5148757944

Fax: 5148758916

Email: wfh@wfh.org

Internet: http://www.wfh.org/index.asp?lang=EN



Hemophilia Federation of America

210 7th St. SE

Suite 200B

Washington, DC 20003

USA

Tel: (202)675-6984

Fax: (202)675-6983

Tel: (800)230-9797

Email: info@hemophiliafed.org

Internet: http://www.hemophiliafed.org



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/



Irish Haemophilia Society

First Floor

Cathedral Court

New Street

Dublin, 7

Ireland

Tel: 353016579900

Fax: 353016579901

Email: info@haemophilia.ie

Internet: http://www.haemophilia.ie/



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