Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Guillain-Barr Syndrome ?
    ### Response:
    Guillain-Barr syndrome is a disorder in which the body's immune system attacks part of the peripheral nervous system. The first symptoms of this disorder include varying degrees of weakness or tingling sensations in the legs. In many instances, the weakness and abnormal sensations spread to the arms and upper body.
    