What is the main underlying issue in β-thalassemia that leads to ineffective erythropoiesis?

• A. Increased production of β-globin chains
• B. Decreased synthesis of α-globin chains
• C. Imbalance in the production of functional hemoglobin
• D. Absence of iron absorption

Answer: (C)

In β-thalassemia, the primary underlying issue is the imbalance in the production of functional hemoglobin. This disorder stems from a genetic defect that reduces or completely halts the production of β-globin chains, which are essential components of hemoglobin.

Normal hemoglobin consists of two α-globin and two β-globin chains. In β-thalassemia, when the β-globin production is diminished due to mutations in the HBB gene, the result is an excess of α-globin chains compared to available β-globin chains. This imbalance leads to the formation of unstable tetramers (usually consisting of α-globin chains only) that precipitate within the erythroid precursors in the bone marrow, causing cell damage and ineffective erythropoiesis.

As a result, the bone marrow produces a large number of red blood cell precursors, but many of these cells die prematurely due to the stress of this imbalance, leading to anemia and a reduced number of functional red blood cells in circulation. Therefore, the key issue in β-thalassemia is this pathological imbalance affecting hemoglobin synthesis, which ultimately results in ineffective erythropoiesis and the clinical manifestations of the disease.