Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Huntington's Disease ?
    ### Response:
    Huntington's disease (HD) is an inherited disease that causes certain nerve cells in the brain to waste away. People are born with the defective gene, but symptoms usually don't appear until middle age. Early symptoms of HD may include uncontrolled movements, clumsiness, and balance problems.
    