Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Mucopolysaccharidosis type IIID ?
    ### Response:
    Mucopolysaccharidosis type IIID (MPS IIID) is an genetic disorder that makes the body unable to break down large sugar molecules called glycosaminoglycans (GAGs, formerly called mucopolysaccharides). Specifically, people with this condition are unable to break down a GAG called heparan sulfate.
    