Paroxysmal nocturnal haemoglobinuria, is a rare, acquired, potentially life-threatening disease of the blood characterised by complement-induced intravascular hemolytic anaemia (anaemia due to destruction of red blood cells in the bloodstream), red urine (due to the appearance of haemoglobin in the urine) and thrombosis. PNH is the only haemolytic anaemia caused by an acquired (rather than inherited) intrinsic defect in the cell membrane (deficiency of glycophosphatidylinositol leading to absence of protective proteins on the membrane). It may develop on its own ("primary PNH") or in the context of other bone marrow disorders such as aplastic anemia ("secondary PNH"). Only a minority have the telltale red urine in the morning.
Allogeneic bone marrow transplantation is the only curative therapy, although the monoclonal antibody eculizumab (Soliris) is effective at reducing the need for blood transfusions, improving quality of life, and reducing the risk of thrombosis. Source: Wikipedia