Sickle cell disease (SCD) simply refers to an assemblage of people who inherited red blood cell disorders. It is the most common genetic disease in the U.S. It is estimated that 70,000-80,000 Americans have sickle cell disease.
SCD is a disease of hemoglobin, a molecule that carries oxygen within red blood cells. In SCD, hemoglobin that is defective causes the red blood cells to become inflexible instead of flexible and form a sickle or a crescent.
SCD is an inherited disease because it is passed on from parents to children through genes. Gene is a unit of heredity that is transferred from a parent to offspring and is held to determine some characteristic of the offspring. Hence, genes are instructions that tell the body how to make all the different substances the body needs to work properly. Since SCD is inherited, the disease is present at birth.
Therefore, sickle cell disease is not contagious; someone cannot “catch” it. You inherit it from your parents. If, for example, one parent has normal hemoglobin ( type AA) and the second parent has abnormal hemoglobin ( type AS, or the sickle cell “trait”), there is a 50% chance that each child will have the sickle cell trait, but they will not have sickle cell disease ( type SS). If, however, both parents have type AS hemoglobin (one normal and one abnormal), there is, a 25% chance that the child will have sickle cell disease, a 50% chance that the child will have sickle cell trait, and a 25% chance that the child will have neither the disease or trait. These chances are the same for each child.
Crescent- or sickle-shaped red blood cells can get stuck in small blood vessels, blocking them. This keeps red blood cells and the oxygen they carry from getting to all parts of the body. There are different types of SCD but, the three most common forms of the disease in the United States are:
1. Hemoglobin SS or sickle cell anemia
2. Hemoglobin SC disease
3. Hemoglobin Sickle beta-thalassemia
Each of these can cause very painful “crisis” episodes and in severe cases lead to stroke, heart attack and death.
SCD affects people of many nationalities which include Italians, Latin Americans, Greeks, African, Arabs, and Asiatic Indians. However, it disproportionately affects people of African descent. All states in the U.S. now screen all newborns for sickle cell. In the U.S., approximately 1 out of 10-12 African Americans has sickle cell trait, and 1 out of 400-500 African American newborns have the disease. Approximately 1 out of 1,000-1,400 Hispanic newborns has the disease. According to the American Journal of Preventive Medicine, in Africa, sickle cell disease (SCD) is stated to be concomitant with a very high rate of childhood mortality, 50%–90%, yet there is a deficiency of dependable, up-to-date information.