PIGA and paroxysmal nocturnal hemoglobinuria: Paroxysmal nocturnal hemoglobinuria (PNH) constitutes a rare bone marrow failure disorder of hematopoietic stem cells caused by an acquired mutation in the phosphatidylinositol glycan class A gene (PIG-A), which leads to loss of glycosylphosphatidylinositol GPI-anchored proteins on the cell membrane [1].