Paroxysmal nocturnal hemoglobinuria

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired, life-threatening disease of the blood characterized by destruction of red blood cells by the complement system, a part of the body's innate immune system. This destructive process occurs due to the presence of defective surface protein DAF on the red blood cell, which normally functions to inhibit such immune reactions. [Source: Wikipedia ]