Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the symptoms of Juvenile Huntington disease ?
    ### Response:
    What are the signs and symptoms of Juvenile Huntington disease? A common sign of juvenile HD is a rapid decline in school performance. Symptoms can also include subtle changes in handwriting and slight problems with movement, such as slowness, rigidity, tremor, and rapid muscular twitching, called myoclonus.
    