Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) familial paroxysmal nonkinesigenic dyskinesia ?
    ### Response:
    Familial paroxysmal nonkinesigenic dyskinesia is a disorder of the nervous system that causes periods of involuntary movement. Paroxysmal indicates that the abnormal movements come and go over time. Nonkinesigenic means that episodes are not triggered by sudden movement.
    