Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Dermatomyositis ?
    ### Response:
    What causes dermatomyositis? The cause of this disorder is unknown. It is theorized that an autoimmune reaction (reactions caused by an immune response against the body's own tissues) or a viral infection of the skeletal muscle may cause the disease. In addition, some doctors think certain people may have a genetic susceptibility to the disease.
    