Below is an instruction from Human. Write a response.
    ### Instruction:
    What are the genetic changes related to glycogen storage disease type III ?
    ### Response:
    Mutations in the AGL gene cause GSDIII. The AGL gene provides instructions for making the glycogen debranching enzyme. This enzyme is involved in the breakdown of glycogen, which is a major source of stored energy in the body. Between meals the body breaks down stores of energy, such as glycogen, to use for fuel.
    