Editorial [Hot Topic:Genetic Disorders of Hemoglobin: Sickle Cell Anemia and Thalassemia (Guest Editors: Elliott Vichinsky, Griffin P. Rodgers and Eliezer Rachmilewitz)]

The hemoglobinopathies are the most common genetic disorders in the world. It is estimated that about 5% of the world population, located mainly in South East Asia and Africa, are carriers of variants in either α or β globin genes and consequently result in two major red blood cell disorders, the thalassemia syndrome and sickle cell anemia. It is no wonder that studies on the genetics, pathophysiology and treatment of these diseases have been carried out extensively for more than half a century. With the rapid progress in research technology and methodology, which enables a better understanding of the basic and clinical pathophysiology, as well as new treatment modalities, there is room to update the scientific and medical community every few years on all the recent developments in this area by leading experts in the field, which will be presented in the following volume of the journal. The up-to-date information on the geographical distribution of the two major hemoglobinopathies, sickle cell disease and thalassemia, with an emphasis on ways and means of prevention are summarized by Professor D. Weatherall. In the following chapter, Drs. D. Rund and S. Fuchareon shed light on the effect of genetic modifiers, which influence the distribution and expression of the various hemoglobinopathies worldwide. Several papers present recent information on the pathophysiology of both diseases. Drs. E. Fibach and E. Rachmilewitz discuss the role of oxidative hemolysis in hemoglobinopathies, with new data that have not been emphasized before. Another aspect discussed by Drs. C. Morris, M. Gladwin and G. Kato is the role of disregulation of nitrous oxide and arginine on the development of pulmonary hypertension in hemoglobinopathies. One of the consequences of the oxidative insult is severe changes in the structure and function of the cell membrane, described by Dr. F. Kuypers, both in sickle cell anemia and thalassemia. Another outcome of the pathological changes in the composition of the red blood cell lipid membrane bilayer is the activation of the coagulation system inducing a hypercoagulable state. This chapter has been written by Drs. S. Singer and K. Ataga. Two papers are dedicated to the issue of iron overload in hemoglobinopathies. Drs. S. Rivella and G. Rechavi present the current status on the regulation of iron absorption and particularly on the role of hepcidin, a protein which regulates iron absorption from the intestines, while Professor M. Cappellini and Dr. A. Piga present the current status of iron chelation in hemoglobinopathies, mainly in thalassemia, using the 3 available iron chelators, deferoxamine, deferipone and deferasirox. Last but not the least, available options for curing thalassemia by bone marrow transplantation are reported with very positive and impressive results by Drs. J. Michlitsch and M. Walters, and what is the present status and future of gene therapy in hemoglobinopathies has been written by Dr. M. Sadelain. Taken together, we hope and believe that going through the different chapters, the reader will be able to obtain an objective up-to-date progress report on all the new epidemiological, pathophysiological, clinical and therapeautical innovations in patients with hemoglobinopathies.