National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Hereditary antithrombin deficiency


Other Names:
Congenital AT-III deficiency; Antithrombin III Deficiency; Congenital Antithrombin III Deficiency; Congenital AT-III deficiency; Antithrombin III Deficiency; Congenital Antithrombin III Deficiency; Thrombophilia due to antithrombin III deficiency; Inherited antithrombin deficiency; Hereditary thrombophilia due to congenital antithrombin deficiency; Hereditary thrombophilia due to congenital antithrombin 3 deficiency See More
Categories:
Subtypes:
Hereditary antithrombin deficiency, also known as antithrombin III deficiency or AT III deficiency, is a disorder in which individuals are at increased risk for developing blood clots. The type of blood clots seen in individuals with this condition are typically clots that form in the deep veins of the leg (deep vein thrombosis or DVT) and clots that lodge in the lungs (pulmonary embolism or PE). Approximately 50% of individuals with hereditary antithrombin deficiency will develop one or more clots in their lifetime, usually after adolescence. Factors that may increase the likelihood of clotting include pregnancy, the use of oral contraceptives, surgery, increasing age, and a lack of movement. Hereditary antithrombin deficiency is caused by mutations in the SERPINC1 gene and is typically inherited in an autosomal dominant manner.[1][2]
Last updated: 8/5/2015

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
80%-99% of people have these symptoms
Reduced antithrombin antigen 0040246
Reduced antithrombin III activity 0001976
30%-79% of people have these symptoms
Deep venous thrombosis
Blood clot in a deep vein
0002625
Pregnancy exposure 0031437
Pulmonary embolism
Blood clot in artery of lung
0002204
Recurrent thromboembolism 0004831
Superficial thrombophlebitis 0002638
5%-29% of people have these symptoms
Arterial thrombosis
Blood clot in artery
0004420
Hepatic vein thrombosis
Blood clot in liver vein
0030243
Mesenteric venous thrombosis 0030248
Portal vein thrombosis
Blood clot in portal vein
0030242
Recurrent spontaneous abortion 0200067
Retinal vein occlusion 0012636
1%-4% of people have these symptoms
Cerebral venous thrombosis
Blood clot in cerebral vein
0005305
Percent of people who have these symptoms is not available through HPO
Arterial occlusion 0025324
Autosomal dominant inheritance 0000006
Autosomal recessive inheritance 0000007
Recurrent thrombophlebitis 0004419
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Last updated: 7/1/2020

Making a diagnosis for a genetic or rare disease can often be challenging. Healthcare professionals typically look at a person’s medical history, symptoms, physical exam, and laboratory test results in order to make a diagnosis. The following resources provide information relating to diagnosis and testing for this condition. If you have questions about getting a diagnosis, you should contact a healthcare professional.

Testing Resources

  • The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
Once a patient with hereditary antithrombin deficiency develops a clot, anticoagulation therapy (usually Warfarin) is often indicated. The duration of therapy after a first clot, especially in children, is a matter of some controversy, but therapy is generally continued for 3-6 months. Individuals who experience a second clot are at a significant risk for future clotting and are candidates for long-term Warfarin therapy. Asymptomatic individuals are often not treated with anticoagulation therapy. Should surgery be necessary, individuals with hereditary antithrombin deficiency may receive antithrombin III concentrate or fresh frozen plasma to boost antithrombin levels.[3]
Last updated: 8/5/2015

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

The prognosis depends on the degree of antithrombin deficiency, the nature of the clots formed, and the number of clots formed. Patients with recurring clots are more likely to suffer a life-threatening clotting event in the future and are best treated with indefinite Warfarin therapy.[4]
Last updated: 8/5/2015

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Hereditary antithrombin deficiency. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Hereditary antithrombin deficiency. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • I have two clotting disorders, antithrombin 3 deficiency and MTHFR. I also only have one kidney. My question is what are all my risks and do the risks outweigh the benefits for getting pregnant? We want to have children, but are scared with everything going on. Thank you! See answer


  1. Hereditary antithrombin deficiency. Genetics Home Reference. February, 2013; http://ghr.nlm.nih.gov/condition/hereditary-antithrombin-deficiency. Accessed 8/5/2015.
  2. Bauer, Kenneth. Antithrombin Deficiency. National Organization for Rare Disorders (NORD). 2015; http://rarediseases.org/rare-diseases/antithrombin-deficiency/. Accessed 8/5/2015.
  3. Harper, James. Antithrombin III Deficiency. Medscape Reference. July 10, 2015; http://emedicine.medscape.com/article/954688-overview. Accessed 8/5/2015.
  4. Harper, James. Antithrombin III Deficiency. Medscape Reference. July 10, 2015; http://emedicine.medscape.com/article/954688-overview. Accessed 8/5/2015.