Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Alpers-Huttenlocher syndrome ?
    ### Response:
    Alpers-Huttenlocher syndrome is one of the most severe of a group of conditions called the POLG-related disorders. The conditions in this group feature a range of similar signs and symptoms involving muscle-, nerve-, and brain-related functions. Alpers-Huttenlocher syndrome typically becomes apparent in children between ages 2 and 4.
    