Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Amyotrophic Lateral Sclerosis ?
    ### Response:
    Amyotrophic lateral sclerosis (ALS) is a nervous system disease that attacks nerve cells called neurons in your brain and spinal cord. These neurons transmit messages from your brain and spinal cord to your voluntary muscles - the ones you can control, like in your arms and legs.
    