Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Mitochondrial Myopathy ?
    ### Response:
    Mitochondrial myopathies are a group of neuromuscular diseases caused by damage to the mitochondriasmall, energy-producing structures that serve as the cells' "power plants." Nerve cells in the brain and muscles require a great deal of energy, and thus appear to be particularly damaged when mitochondrial dysfunction occurs.
    