Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Tubular aggregate myopathy ?
    ### Response:
    Tubular aggregate myopathy is a very rare muscle disease where the presence of tubular aggregates represent the major, if not sole, pathologic change in the muscle cell.  It is often characterized by muscle weakness or stiffness, cramps, and exercise induced muscle fatigue.
    