What is TAR Syndrome?
Thrombocytopenia Absent Radius (TAR) Syndrome is a rare genetic disorder. It is characterized by low levels of platelets in the blood (thrombocytopenia), absence (aplasia) of the bone on the thumb side of the forearm (radius) on both arms, and underdevelopment (hypoplasia) or absence of the bone on the pinky-side of the forearm (ulna). Platelets are very important for normal blood clotting. Consequently, thrombocytopenia results in potentially severe bleeding episodes (hemorrhaging) primarily during infancy. Children with TAR Syndrome frequently have malformations of their hands, but their thumbs are always present. Other abnormalities may include malformations of the heart, legs, and hip sockets; kidney defects; and mental retardation resulting from bleeding in the skull.