PIGA and paroxysmal nocturnal hemoglobinuria: Paroxysmal nocturnal haemoglobinuria (PNH) is a rare clonal disease caused by a phosphatidylinositol glycan class A (PIGA) gene mutation in haematopoietic stem cells (HSCs), resulting in incomplete glycosyl‐phosphatidylinositol (GPI) anchored proteins (GPI‐APs) on the cell surface and presenting as intravascular haemolysis, bone marrow (BM) failure and thrombosis.1, 2