Paroxysmal nocturnal hemoglobinuria
(PNH) is an acquired disorder that leads to the premature death and impaired production of blood cells. It can occur at any age, but is usually diagnosed in young adulthood. People with PNH have recurring episodes of symptoms due to hemolysis, which may be triggered by stresses on the body such as infections or physical exertion. This results in a deficiency of various types of blood cells and can cause signs and symptoms such as fatigue, weakness, abnormally pale skin (pallor), shortness of breath, and an increased heart rate. People with PNH may also be prone to infections and abnormal blood clotting (thrombosis) or hemorrhage, and are at increased risk of developing leukemia. It is caused by acquired, rather than inherited, mutations in the PIGA gene; the condition is not passed down to children of affected individuals. Sometimes, people who have been treated for aplastic anemia may develop PNH. The treatment of PNH is largely based on symptoms; stem cell transplantation is typically reserved for severe cases of PNH with aplastic anemia or those whose develop leukemia. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.