Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) TAR syndrome ?
    ### Response:
    TAR syndrome is characterized by the absence of a bone called the radius in each forearm, short stature, and thrombocytopenia. The thrombocytopenia often appears first in infancy but becomes less severe or returns to normal over time. Infants and young children are particularly vulnerable to episodes of severe bleeding which may occur in the brain and other organs.
    