Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Sickle Cell Anemia ?
    ### Response:
    Sickle cell anemia is a disease in which your body produces abnormally shaped red blood cells. The cells are shaped like a crescent or sickle. They don't last as long as normal, round red blood cells. This leads to anemia. The sickle cells also get stuck in blood vessels, blocking blood flow.
    