β-Thalassemia Intermedia: A Bird's-Eye View

Abstract

Beta-thalassemia is due to a defect in the synthesis of the beta-globin chains, leading to alpha/beta imbalance, ineffective erythropoiesis, and chronic anemia. The spectrum of thalassemias is wide, with one end comprising thalassemia minor, which consists of a mild hypochromic microcytic anemia with no obvious clinical manifestations, while on the other end is thalassemia major, characterized by patients who present in their first years of life with profound anemia and regular transfusion requirements for survival. Along the spectrum lies thalassemia intermedia, a term developed to describe patients with manifestations that are neither mild enough nor severe enough to be classified in the spectrum's extremes. Over the past decade, our understanding of β-thalassemia intermedia has increased tremendously with regards to molecular information as well as pathophysiology. It is now clear that β-thalassemia intermedia has a clinical presentation as well as complications associated with the disease that are different from those of β-thalassemia major. This review is designed to tackle issues related to β-thalassemia intermedia from the basic definition of the disease to paramedical issues, namely the quality of life in these patients. Genetics and pathophysiology are revisited, as well as the complications specific to this disease. These complications include effects on several organ systems, including the cardiovascular, hepatic, endocrine, renal, brain, and skeletal systems. Extramedullary hematopoiesis is also discussed in this article. Risk factors are highlighted and cutoffs are identified to minimize morbidities in β-thalassemia intermedia. Several treatment modalities are considered by shining a light on the pros and cons of each modality, as well as the role of special pharmacological agents in the progress of the disease and its morbidities. Finally, health-related quality of life is discussed in these patients with a direct comparison to the more severe β-thalassemia major.

Keywords: Ineffective erythropoiesis; Iron chelation; Thalassemia; Thalassemia intermedia; iron overload.

Figure 1. Indications for transfusion

Figure 2. Algorithm for iron chelation Abbreviations: NTDT: non-transfusion dependent thalassemia, LIC: liver iron concentration, SF: serum ferritin, DFX: deferasirox.