Sickle cell anemia is an inherited blood disorder. What are its defining features and which group is it most associated with?

• A. Inherited blood disorder marked by defective hemoglobin that gives RBCs a crescent shape; it mainly affects African Americans.
• B. Acquired autoimmune disorder affecting red blood cells
• C. A bacterial infection of the blood
• D. A vitamin deficiency-related anemia

Answer: (A)

Sickle cell anemia is defined by a genetic change in the beta-globin gene that produces abnormal hemoglobin S. When oxygen levels drop, hemoglobin S tends to polymerize, causing red blood cells to become stiff and take on a crescent, or sickle, shape. These misshapen cells die more quickly, leading to chronic anemia, and they can block small blood vessels, causing pain crises and organ complications. It’s inherited in an autosomal recessive pattern, so two carriers have a good chance of having an affected child. Because the HbS allele is most common in people of African descent, the condition is most associated with African Americans, though it can occur in other populations as well.

The other options describe different processes: an acquired autoimmune process, a bacterial infection in the blood, or anemia from nutrient deficiencies, none of which match the genetic cause, the crescent-shaped cells, or the typical population association of sickle cell disease.