Paroxysmal nocturnal hemoglobinuria (PNH) has long been recognized as a hemolytic disorder by its predominant clinical features of chronic intravascular hemolysis i.e. chronic anemia with exacerbations and intermittent dark urine from hemoglobinuria. With recent studies for the better understanding of the disease, PNH is recognized as an acquired hemolytic anemia, which has originated through the clonal expansion of a hematopoietic progenitor cell that has a somatic mutation of the X linked, phosphatidylinositolglycan class A (PIG-A) gene. PNH can also be classified as an acquired non-malignant, clonal hematopoietic stem cell disorder. It is characterized by chronic intravascular hemolysis with paroxysms, a tendency ...