sickle cell trait, the heterozygous form of sickle cell anemia, characterized by the presence of both hemoglobin S and hemoglobin A in the red blood cells. Anemia and the other signs of sickle cell anemia do not occur. People who have the trait are informed of and counseled about the possibility of having an infant with sickle cell disease if both parents have the trait. See also hemoglobin S.
