Which of the following statements regarding sickle cell disease is correct?

• A. The red blood cells of patients with sickle cell disease are round and contain hemoglobin.
• B. Sickle cell disease is an inherited blood disorder that causes the blood to clot too quickly.
• C. In sickle cell disease, the red blood cells are abnormally shaped and are less able to carry oxygen.
• D. Because of their abnormal shape, red blood cells in patients with sickle cell disease are less apt to lodge in a blood vessel.

Answer: (C)

Sickle cell disease centers on a genetic change in hemoglobin that makes the abnormal HbS form fibers when oxygen levels drop, bending red blood cells into a crescent or sickle shape. These misshapen cells become stiff and less flexible, so they don’t move smoothly through tiny vessels. That impaired flow reduces oxygen delivery to tissues and can lead to painful vaso-occlusive crises and hemolytic anemia. The statement describing red blood cells as abnormally shaped and less able to carry oxygen best captures both the structural change and the functional consequence: oxygen transport is compromised because the cells are misshapen. The other descriptions miss the hallmark features—round cells with normal hemoglobin aren’t accurate for this disease, the condition isn’t defined by overly rapid blood clotting, and sickled cells tend to lodge in vessels rather than avoid lodging.