Decreased synthesis of globin chains is most characteristic of which disorder?

Decreased synthesis of globin chains is most characteristic of which disorder?

• A. Beta-thalassemia
• B. Alpha-thalassemia
• C. Sideroblastic anemia
• D. Megaloblastic anemia

Answer: (A)

When a disorder causes reduced production of one type of globin chain, the balance between the globin components of hemoglobin is disrupted. In beta-thalassemia, beta-globin synthesis is decreased, so there are too many free alpha chains that cannot form stable hemoglobin. These unstable alpha chains precipitate in developing and mature red cells, leading to ineffective erythropoiesis and hemolysis, which produces a microcytic, hypochromic anemia with characteristic changes in hemoglobin fractions. The other options involve different problems: sideroblastic anemia is a heme synthesis issue, megaloblastic anemia stems from impaired DNA synthesis, and alpha-thalassemia involves decreased alpha-chain production (a globin-chain issue but not the classic presentation emphasized by this question). Thus, the presentation described most characteristic of decreased globin-chain synthesis points to beta-thalassemia.

When a disorder causes reduced production of one type of globin chain, the balance between the globin components of hemoglobin is disrupted. In beta-thalassemia, beta-globin synthesis is decreased, so there are too many free alpha chains that cannot form stable hemoglobin. These unstable alpha chains precipitate in developing and mature red cells, leading to ineffective erythropoiesis and hemolysis, which produces a microcytic, hypochromic anemia with characteristic changes in hemoglobin fractions. The other options involve different problems: sideroblastic anemia is a heme synthesis issue, megaloblastic anemia stems from impaired DNA synthesis, and alpha-thalassemia involves decreased alpha-chain production (a globin-chain issue but not the classic presentation emphasized by this question). Thus, the presentation described most characteristic of decreased globin-chain synthesis points to beta-thalassemia.