Paroxysmal nocturnal haemoglobinuria.

The analysis of the abnormality of the membrane in paroxysmal nocturnal haemoglobinuria is an exercise in complexity complexified--of Ossa atop Pelion. To understand it, we will need to understand fully the complexities of the complement system and the complexities of the structure of the membrane and the complexity of their concert interaction. Added to this are the complexities of growth and development of the haematopoietic cells--a problem we have not discussed at all despite its importance in the pathophysiology of PNH. It is little wonder that a disease which is uncommon but not rare continues to fascinate investigators from a wide variety of disciplines. If, as has been (falsely) said, more people studied the disease than had it, it would be because it presents questions of such fundamental interest. In unravelling its mysteries, many problems related to the normal functioning of cells, complement and a haematopoiesis have been and will continue to be solved.