Since sickle cell is a mutation of a strand of chromosomes, there are several different strains or variations. Here are the five most commonly documented:
Sickle cell trait: The person is carrying the defective gene, HbS, but also has some normal hemoglobin, HbA. Persons with sickle cell trait are usually without symptoms of the disease but have mild anemia. Under intense, stressful conditions, exhaustion, hypoxia (low oxygen), and/or severe infection, the sickling of the defective hemoglobin may occur and result in some complications associated with the sickle cell disease. This affects 1 in 12 African Americans.
Sickle cell anemia: The person has most or all of the normal hemoglobin (HbA) replaced with the sickle hemoglobin (HbS). It is the most common and most severe form of the sickle cell variations. These persons suffer from a variety of complications due to the shape and thickness of the sickled cells. Severe and chronic anemia is also a common characteristic for children with HbSS. This is what I have.
Sickle cell – hemoglobin C disease: The person has both HbS and HbC. This is often referred to as HbSC. Hemoglobin C causes red blood cells, called target cells, to develop. Having just some hemoglobin C and normal hemoglobin, this person might be mildy anemic. These persons often suffer some of the complications associated with SCD, but to a milder degree. Vaso-occlusive crises (the flow of blood is blocked because the sickled cells have become stuck in the blood vessels), organ damage from repeated sickling and anemia, and high risk for infection are all similar traits for HbSS and HbSC.
Sickle cell – hemoglobin E disease: This variation is similar to sickle cell-C disease except that an element has been replaced in the hemoglobin molecule and is often seen in Southeast Asia populations. Some persons with hemoglobin E disease are without symptoms. However, under certain conditions, such as exhaustion, hypoxia, severe infection, and/or iron deficiency, some mild to moderate anemia may occur.
Hemoglobin S-beta-thalassemia: This involves an inheritance of both the thalassemia and sickle cell genes. The disorder produces symptoms of moderate anemia and many of the same conditions associated with sickle cell disease. While this disorder more often has milder symptoms than sickle cell disease, it may also produce exacerbations as severe as those of sickle cell disease.