Thrombocytopenia and absent radii (TAR) syndrome associated with horseshoe kidney.

The TAR syndrome is an inherited disorder characterized by limb abnormalities, especially absent radii, and hypomegakaryocytic thrombocytopenia. Previous reports have included two infants with genitourinary abnormalities. We report a newborn with bilaterally absent radii and foreshortened ulnae, hypoplastic humeri, a left clubfoot, a ventricular septum defect, and persistent thrombocytopenia. This constellation of abnormalities is consistent with the TAR syndrome. In addition, he had a horseshoe kidney with parenchyma of normal appearance. This is the first report of horseshoe kidney in association with the TAR syndrome.