TAR syndrome

Chromosome 1 to 1q21.1

TAR syndrome (Thrombocytopenia with Absent Radius) is a rare genetic disorder characterized by the absence of the radius bone in the forearm and a significantly reduced platelet count, leading to bleeding tendencies. The condition is present from birth and can vary in severity.

Presentation

Individuals with TAR syndrome typically present with bilateral absence of the radius bone, while the thumbs are usually present, distinguishing it from other radial ray defects. The thrombocytopenia, or low platelet count, can lead to easy bruising, nosebleeds, and bleeding gums. In severe cases, it can cause internal bleeding and hemorrhages.

Genetics

TAR syndrome is inherited in an autosomal recessive pattern. It is associated with mutations in the RBM8A gene. Both parents of an affected individual typically carry one copy of the mutated gene but do not show symptoms of the condition.

Diagnosis

Diagnosis of TAR syndrome is based on clinical findings and can be confirmed through genetic testing. Prenatal diagnosis is possible through ultrasound and genetic testing if there is a known family history of the disorder.

Management

Management of TAR syndrome involves addressing the hematological and orthopedic issues. Platelet transfusions may be necessary to manage severe thrombocytopenia, especially during surgeries or in response to significant bleeding episodes. Orthopedic interventions may include surgical correction of limb deformities and physical therapy to improve function.

Prognosis

The prognosis for individuals with TAR syndrome varies. With appropriate medical care, many individuals can lead relatively normal lives. However, the severity of the condition and the presence of associated anomalies can impact overall health and quality of life.

Related Conditions

• Fanconi anemia
• Thrombocytopenia
• Radial ray defect
• Congenital limb deformities

See Also

• Genetic disorders
• Hematology
• Orthopedic surgery