Which of the following best describes a characteristic of sickle cell anemia?

Sickle cell anemia is characterized by the presence of abnormal hemoglobin, specifically hemoglobin S, which differs from normal hemoglobin A. This genetic mutation causes red blood cells to become rigid and shaped like a "sickle" or crescent instead of their typical disc shape. The sickle-shaped cells tend to clump together, leading to blockages in small blood vessels, which can cause pain and various complications. The abnormal hemoglobin is the root cause of many of the symptoms and complications associated with sickle cell anemia, making this the defining characteristic of the condition.

Other options do not accurately represent the nature of sickle cell anemia. It affects both males and females, does not primarily lead to respiratory problems, and there is currently no simple cure for the disease, although treatments exist to manage symptoms and complications.