Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Cold agglutinin disease ?
    ### Response:
    What causes cold agglutinin disease? Cold agglutinin disease is typically classified as primary (unknown cause) or secondary (caused by an underlying condition). Secondary cold agglutinin disease may be associated with: Bacterial Infections such as mycoplasma, Legionnaires' disease, syphilis, listeriosis, or E.
    