Iron overload and iron-chelating therapy in hemoglobin E-beta thalassemia

Whereas hemoglobin (Hb) E-beta thalassemia is recognized as probably the mo st common serious hemoglobinopathy worldwide, its natural history remains p oorly defined. The interaction of hemoglobin E and beta -thalassemia result in a wide spectrum of clinical disorders, some indistinguishable from thal assemia major and some milder and not transfusion-dependent. Partially as a result of this wide range of phenotypes, clear guidelines for approaches t o transfusion and to iron-chelating therapy for patients with Hb E-beta tha lassemia have not been developed. By contrast, data that have accumulated d uring the past 10 years in patients with beta -thalassemia permit a quantit ative approach to the management of iron overload and provide guidelines fo r the control of body iron burden in individual patients treated with iron- chelating therapy. These guidelines may be applicable to patients with Hb E -beta thalassemia. Preliminary evidence from our studies of iron loading in affected patients with Hb E-beta thalassemia in Sri Lanka suggest that thi s disorder may be associated with variable, but accelerated, gastrointestin al iron absorption, and that the iron loading associated with chronic trans fusions in patients with Hb E-beta thalassemia is similar to that observed in patients with beta -thalassemia. These data, in the only cohort of patie nts with Hb E-beta thalassemia to have undergone quantitative assessment of body iron burden, suggest that the principles that guide assessment of iro n loading and initiation of chelating therapy in patients with beta -thalas semia may be generally applicable to those with Rb E-beta thalassemia. Furt her quantitative studies in both nontransfused and transfused patients will be necessary to permit firm conclusions.