Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Chronic Lymphocytic Leukemia ?
    ### Response:
    Key Points
                    - Chronic lymphocytic leukemia is a type of cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell).    - Leukemia may affect red blood cells, white blood cells, and platelets.    - Older age can affect the risk of developing chronic lymphocytic leukemia.
    