Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Inclusion Body Myositis ?
    ### Response:
    Inclusion body myositis (IBM) is one of a group of muscle diseases known as the inflammatory myopathies, which are characterized by chronic, progressive muscle inflammation accompanied by muscle weakness. The onset of muscle weakness in IBM is generally gradual (over months or years) and affects both proximal (close to the trunk of the body) and distal (further away from the trunk) muscles.
    