Sickle cell trait occurs when a person inherits a sickle cell
disease gene but does not develop symptoms. Sickle cell disease is a blood
disorder in which the body produces an abnormal type of the oxygen-carrying
substance hemoglobin in the red blood cells.
Normal hemoglobin is
called hemoglobin A, but people with sickle cell disease have only hemoglobin
S, which turns normal, round red blood cells into abnormally curved (sickle)
Normally, a person inherits two genes (one from each
parent) that produce beta-globin, a protein needed to produce normal hemoglobin
(hemoglobin A). A person with sickle cell trait inherits one normal beta-globin
gene (hemoglobin A) and one defective gene (hemoglobin S).
with sickle cell trait rarely have symptoms due to the condition, because they
also have some normal hemoglobin. But they can pass the sickle cell gene to
A person in whom both beta-globin genes are
abnormal (they produce hemoglobin S) has sickle cell disease, which can cause
serious problems. Both parents must have either the sickle cell trait or the
disease itself for a child to have sickle cell disease.
E. Gregory Thompson, MD - Internal Medicine & Adam Husney, MD - Family Medicine & Martin Steinberg, MD - Hematology