What Do We Know About Heredity and Sickle Cell Disease?
Sickle cell disease is the most common inherited blood disorder
in the United States. Approximately 80,000 Americans have the
In the United States, sickle cell disease is most prevalent
among African Americans. About one in 12 African Americans and about one in 100
Hispanic Americans carry the sickle cell trait, which means they are carriers of
Sickle cell disease is caused by a mutation in the
hemoglobin-Beta gene found on chromosome 11. Hemoglobin transports oxygen from
the lungs to other parts of the body. Red blood cells with normal hemoglobin
(hemoglobin-A) are smooth and round and glide through blood vessels.
In people with sickle cell disease, abnormal hemoglobin
molecules – hemoglobin S – stick to one another and form long, rod-like
structures. These structures cause red blood cells to become stiff, assuming a
sickle shape. Their shape causes these red blood cells to pile up, causing
blockages and damaging vital organs and tissue.
Sickle cells are destroyed rapidly in the bodies of people with
the disease, causing anemia. This anemia is what gives the disease its commonly
known name – sickle cell anemia.
The sickle cells also block the flow of blood through vessels,
resulting in lung tissue damage that causes acute chest syndrome, pain episodes,
stroke and priapism (painful, prolonged erection). It also causes damage to the
spleen, kidneys and liver. The damage to the spleen makes patients – especially
young children – easily overwhelmed by bacterial infections.