PIGA and paroxysmal nocturnal hemoglobinuria: Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal hematopoietic stem cell disorder caused by a somatic mutation in phosphatidylinositol N-acetylglucosaminyltransferase subunit A (PIGA), whose gene product is required for the synthesis of glycosylphosphatidylinositol (GPI) anchors [1].