What is the hereditary autosomal recessive blood disorder characterized by sickle-shaped red blood cells?

• A. Sickle cell anemia
• B. Thalassemia
• C. Hemophilia
• D. Polycythemia

Answer: (A)

Sickle cell anemia is a hereditary autosomal recessive condition where the red blood cells become sickle-shaped due to abnormal hemoglobin S. Inheriting two copies of the HbS gene causes red cells to polymerize and deform when oxygen levels drop, making them rigid and prone to causing painful vaso-occlusive episodes and chronic hemolytic anemia. Carriers with one mutant gene are usually largely asymptomatic, but can have mild symptoms under stress. This combination of autosomal recessive inheritance and characteristic sickling of red blood cells makes sickle cell anemia the best match for the description. Other options involve different problems—thalassemia affects globin production, hemophilia is a clotting disorder, and polycythemia is an excess of red cells without abnormal shape.