Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) actin-accumulation myopathy ?
    ### Response:
    Actin-accumulation myopathy is a disorder that primarily affects skeletal muscles, which are muscles that the body uses for movement. People with actin-accumulation myopathy have severe muscle weakness (myopathy) and poor muscle tone (hypotonia) throughout the body.
    