TAR syndrome (thrombocytopenia with absent radius) is a rare genetic disorder that is characterized by the absence of the radius bone in the forearm and a dramatically reduced platelet count. It is associated with cardiac defects, dysmorphic features, and petechiae. It involves a 1q21 deletion with RMB8A variant on other allele.

Signs and symptoms

  • Presents with symptoms of thrombocytopenia, or a lowered platelet count, leading to bruising and potentially life-threatening hemorrhage.
  • Absence of the radius bone in the forearm with preservation of the thumb.

Other common links between people with TAR syndrome include anemia, heart problems, kidney problems, knee joint problems, and frequently milk allergy. Different cases with leukemia in patients with TAR are described in.

Genetics

thumb|upright=1.5|The [[Locus (genetics)|cytogenetic location (pink box) of the RBM8A gene 0lon 1q21.1]]

This condition requires mutations in both chromosomes. The first mutation is inheritance of a 1q21.1 deletion and the second is in the remaining in the RBM8A gene.

Approximately 95% of TAR patients have one non-functional copy of the RBM8A gene.

Treatment

Treatments range from platelet transfusions 40 years later Hall collected 40 cases and introduced the name "Thrombocytopenia with absent radius". In 1988 Hedberg published an article with 100 cases.

References

Further reading

  • Thrombocytopenia Absent Radii research study of Inherited Bone Marrow Failure Syndromes (IBMFS)
  • GeneReview/NCBI/NIH/UW entry on Thrombocytopenia Absent Radius Syndrome