Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Creutzfeldt-Jakob disease ?
    ### Response:
    Creutzfeldt-Jakob disease (CJD) is a rare fatal brain disorder that usually occurs later in life and runs a rapid course. In the early stages of the disease, patients may have failing memory, behavior changes, impaired coordination, and vision problems. As CJD progresses, mental deterioration becomes severe, and they can have uncontrolled movements, blindness, weakness, and go into a coma.
    