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Genetic and Rare Diseases Information Center (GARD)

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TAR syndrome

Other Names for this Disease
  • Absent radii and thrombocytopenia
  • Thrombocytopenia absent radii
  • Thrombocytopenia absent radius syndrome
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TAR syndrome is characterized by the absence of a bone called the radius in each forearm, short stature, and thrombocytopenia. The thrombocytopenia often appears first in infancy but becomes less severe or returns to normal over time. Infants and young children are particularly vulnerable to episodes of severe bleeding which may occur in the brain and other organs. Children who survive this period and do not have damaging bleeding in the brain usually have a normal life expectancy and normal intellectual development. Other signs and symptoms vary but may include heart defects, kidney defects, and other skeletal abnormalities. About half of people with TAR syndrome also have difficulty digesting cow's milk. TAR syndrome is thought be caused by a deletion of genes on chromosome 1q21.1 in concert with another genetic change that has yet to be identified. Click here to see a diagram of chromosome 1.[1]
Last updated: 3/26/2012


  1. Thrombocytopenia-absent radius syndrome. Genetics Home Reference. October 2012;
Your Questions Answered
by the Genetic and Rare Diseases Information Center

1 question(s) from the public on TAR syndrome have been answered. See questions and answers. You can also submit a new question.

Basic Information

  • The American Society for Surgery of the Hand provides information on congenital differences of the hand. Click on American Society for Surgery of the Hand to view the information page.
  • The Children’s Hospital Boston has a information page on congenital limb defects. Click on the link above to view this information page.
  • Genetics Home Reference (GHR) contains information on TAR syndrome. This website is maintained by the National Library of Medicine.
  • Madisons Foundation has an information page on TAR syndrome.
  • More information on limb abnormalities can be found at the following link from MEDLINEplus, the National Library of Medicine Web site designed to help you research your health questions.
  • The National Cancer Institute provides the most current information on cancer for patients, health professionals, and the general public.  Click on the link to view information on this topic. 
  • The University of Kansas Medical Center Web site lists resources for people with limb defects and their families. Click on the link above to view this list.

In Depth Information

  • Medscape Reference provides information on this topic. Click on the link to view this information. You may need to register to view the medical textbook, but registration is free.
  • The Online Mendelian Inheritance in Man (OMIM) is an 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.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss TAR syndrome. Click on the link to view a sample search on this topic.