Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Geniospasm ?
    ### Response:
    Hereditary geniospasm is a movement disorder that causes episodes of involuntary tremors of the chin and lower lip. The episodes may last anywhere from a few seconds to hours and may occur spontaneously or be brought on by stress. The episodes usually first appear in infancy or childhood and tend to lessen in frequency with age.
    