PIGA and paroxysmal nocturnal hemoglobinuria: The pathophysiology of PNH is the genetic mutation of Phosphatidylinositol glycan anchor biosynthesis, class A(PIG-A) gene on chromosome Xp22.1, whose gene product is necessary for the synthesis of glycosylphosphatidylinositol (GPI) anchors; the reduction or deletion of the GPI anchor is the result of mutation of PIG-A gene, which leads to the deficiency of GPI-anchored proteins (GPI-APs) (Figure 1) (5).