Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) glycogen storage disease type IV ?
    ### Response:
    Glycogen storage disease type IV (GSD IV) is an inherited disorder caused by the buildup of a complex sugar called glycogen in the body's cells. The accumulated glycogen is structurally abnormal and impairs the function of certain organs and tissues, especially the liver and muscles.
    