Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) paroxysmal nocturnal hemoglobinuria ?
    ### Response:
    Paroxysmal nocturnal hemoglobinuria is an acquired disorder that leads to the premature death and impaired production of blood cells. The disorder affects red blood cells (erythrocytes), which carry oxygen; white blood cells (leukocytes), which protect the body from infection; and platelets (thrombocytes), which are involved in blood clotting.
    