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

Warfarin sensitivity


Other Names:
Coumadin sensitivity
Warfarin sensitivity is a condition that is characterized by a reduced tolerance for a "blood-thinning" medication called warfarin. Warfarin is an anticoagulant that is often prescribed to people who are at an increased risk for blood clots. People with a warfarin sensitivity respond more strongly to lower doses of warfarin and are, therefore, more likely to experience an overdose or other serious side effects from the medication. They may experience abnormal bleeding in the brain, gastrointestinal tract, or other tissues even at average doses. The metabolism of warfarin and the drug's effects in the body are complex traits that are determined by several genes as well as environmental and lifestyle factors such as gender, age, weight, diet, and other medications. Two specific genetic polymorphisms in the CYP2C9 and VKORC1 genes account for approximately 30-40% of variation in the response to warfarin and can be passed on to future generations in an autosomal dominant manner.
Last updated: 6/18/2015

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
Percent of people who have these symptoms is not available through HPO
Abnormality of blood and blood-forming tissues 0001871
Abnormality of metabolism/homeostasis
Laboratory abnormality
Metabolism abnormality
[ more ] 		0001939
Autosomal dominant inheritance 0000006
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Last updated: 7/1/2020

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

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 Warfarin sensitivity. 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.

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

In-Depth Information

  • 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. 
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Warfarin sensitivity. Click on the link to view a sample search on this topic.

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.

  1. Warfarin sensitivity. Genetics Home Reference. June 2015; http://ghr.nlm.nih.gov/condition/warfarin-sensitivity.
  2. Warfarin sensitivity. My46. February 2013; https://www.my46.org/trait-document?trait=Warfarin%20sensitivity&parent=Medication%20Response&type=profile.