Changing patterns of thalassemia worldwide.

Thalassemia is a growing global public health problem with an estimated 900,000 births of clinically significant thalassemia disorders expected to occur in the next 20 years. This growth will occur in disorders previously uncommon in many parts of the world. In particular, hemoglobin (Hb) E-beta-thalassemia and Hb H disease account for much of the projected increases in thalassemia. Worldwide, Hb E-beta-thalassemia is one of the most frequent hemoglobinopathies. The incidence of Hb E approaches 60% of the populations in many regions of Southeast Asia. In coastal regions of North America, its prevalence is rapidly growing. The severity of Hb E-beta-thalassemia ranges from a complete lack of symptoms to transfusion dependence. alpha-Thalassemia diseases, often considered benign, are now recognized to be more severe than originally reported. Hb H, Hb H-Constant Spring (CS), and homozygous alpha-thalassemia affect at least a million people worldwide. California considers Hb H disease a public health problem and has initiated a neonatal screening program for Hb H and particularly Hb H-CS. Homozygous alpha-thalassemia, usually fatal, is also being more commonly detected. Several regions have initiated universal prenatal screening programs to address homozygous alpha-thalassemia. In summary, the prognosis for thalassemia disorders is improving, but prenatal diagnosis and neonatal screenings are needed. Comprehensive services that address language and social barriers as well as access to Hb F-enhancing agents and transfusions are needed.