Final answer:
The abnormality in the red blood cells of a patient with sickle-cell anemia is their irregularly shaped, sickle-like appearance. These abnormal cells can lead to serious complications by obstructing blood flow in capillaries.
Step-by-step explanation:
The abnormality observed in the red blood cells of a patient with sickle-cell anemia is their irregularly shaped nature. Rather than being round with a dimple in the middle, sickled cells are elongated and crescent, or banana-shaped. This occurs due to an abnormal type of hemoglobin, known as hemoglobin S, which causes the red blood cells to deform and resemble a sickle shape under low oxygen concentrations. These sickle-shaped cells can become lodged in narrow blood vessels, leading to various complications such as oxygen deprivation to tissues, pain, and even more severe conditions.
Sickle-cell anemia is a genetic disorder that prominently affects individuals of African descent, and the shape change in erythrocytes (red blood cells) is a core characteristic. Therefore, the correct option from the provided choices is 2) Irregularly shaped red blood cells.