Which type of anemia occurs primarily in African Americans?

Sickle cell anemia is a genetic blood disorder that is particularly prevalent among individuals of African descent. This condition is caused by a mutation in the hemoglobin gene that leads to the production of abnormal hemoglobin, known as hemoglobin S. When oxygen levels are low, this abnormal hemoglobin causes red blood cells to assume a rigid, sickle shape. These sickle-shaped cells are not flexible and can become stuck in blood vessels, leading to painful episodes and other serious complications.

The higher occurrence of sickle cell anemia in African Americans is attributed to the historical presence of malaria in Africa. The sickle cell trait provides some resistance against malaria, which may have led to a higher frequency of the gene in populations where malaria was endemic. As a result, sickle cell anemia has become more common in African American populations compared to other types of anemia, which are not specifically associated with geographic or ethnic groups to the same extent.

Other forms of anemia such as iron-deficiency anemia, thalassemia, and aplastic anemia do not exhibit the same strong ethnic or racial predispositions nor are they primarily linked to African American populations. Thus, sickle cell anemia stands out as the correct answer due to its direct association with African ancestry.