Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Multifocal motor neuropathy ?
    ### Response:
    What causes multifocal motor neuropathy? The exact underlying cause of multifocal motor neuropathy (MMN) is poorly understood. It is considered an immune-mediated disorder (due to an abnormal immune system response), both because IVIG therapy improves symptoms, and many patients have anti-GM1 antibodies.
    