Somatic PIGA gene mutations had been identified in many patients with PNH, and it had been proposed that germline PIGA gene mutations were lethal due to an early block in embryogenesis before the development of the mesoderm and the endoderm, resulting from loss of GPI anchored co-receptors involved in BMP4 signalling [23–26]. This evidence concerns the gene PIGA and paroxysmal nocturnal hemoglobinuria.