Thrombocytopenia Absent Radius Syndrome

National Organization for Rare Disorders, Inc.

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It is possible that the main title of the report Thrombocytopenia Absent Radius Syndrome 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.


  • radial aplasia-amegakaryocytic thrombocytopenia
  • radial aplasia-thrombocytopenia syndrome
  • TAR syndrome
  • thrombocytopenia-absent radii syndrome

Disorder Subdivisions

  • None

General Discussion

Thrombocytopenia-absent radius (TAR) syndrome is a rare disorder that is present at birth (congenital). It is characterized by low levels of platelets in the blood (thrombocytopenia) and absence (aplasia) of the long, thin bones of the forearms (radii). Other abnormalities are often present including additional skeletal defects such as absence or underdevelopment of the other bone of the forearm (ulna), structural malformations of the heart (congenital heart defects), and kidney (renal) defects. Affected individuals may be abnormally short for their age (short stature) and exhibit cow's milk intolerance. TAR syndrome is inherited as an autosomal recessive genetic disorder and caused by deletion and/or mutations in the RBM8A gene.

Supporting Organizations

American Heart Association

7272 Greenville Avenue
Dallas, TX 75231
Tel: (214)784-7212
Fax: (214)784-1307
Tel: (800)242-8721

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

March of Dimes Birth Defects Foundation

1275 Mamaroneck Avenue
White Plains, NY 10605
Tel: (914)997-4488
Fax: (914)997-4763

NIH/National Heart, Lung and Blood Institute

P.O. Box 30105
Bethesda, MD 20892-0105
Tel: (301)592-8573
Fax: (301)251-1223


P.O. Box 54
Cornwall, TR13 8WD
United Kingdom
Tel: 8451306225
Fax: 8451300262

For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders (NORD). A copy of the complete report can be downloaded free from the NORD website for registered users. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational therapies (if available), and references from medical literature. For a full-text version of this topic, go to and click on Rare Disease Database under "Rare Disease Information".

The information provided in this report is not intended for diagnostic purposes. It is provided for informational purposes only. NORD recommends that affected individuals seek the advice or counsel of their own personal physicians.

It is possible that the title of this topic is not the name you selected. Please check the Synonyms listing to find the alternate name(s) and Disorder Subdivision(s) covered by this report

This disease entry is based upon medical information available through the date at the end of the topic. Since NORD's resources are limited, it is not possible to keep every entry in the Rare Disease Database completely current and accurate. Please check with the agencies listed in the Resources section for the most current information about this disorder.

For additional information and assistance about rare disorders, please contact the National Organization for Rare Disorders at P.O. Box 1968, Danbury, CT 06813-1968; phone (203) 744-0100; web site or email

Last Updated:  1/13/1970
Copyright  2013 National Organization for Rare Disorders, Inc.