Paroxysmal nocturnal hemoglobinuria (PNH) is a rare but potentially serious blood disease that can affect people of any age. Individuals with PNH acquire a defect in the most immature bone marrow cells, the stem cells, that leads to increased hemolysis, or destruction, of red cells in the blood stream, causing the urine to turn red or dark and causing anemia.*

There is also a tendency for increased thrombosis of veins in the abdomen leading to potentially fatal liver failure. The PNH defect can also occur without significant hemolysis or clotting. PNH may occur as an isolated disorder or PNH may occur in association with aplastic anemia and/or MDS.*