Sickle cell anemia is an inherited condition in which there aren't enough healthy red blood cells to carry oxygen through an individual's body. The red blood cells of a healthy individual are flexible and round, and they move through blood vessels with no problem, transporting oxygen successfully. However, a person with sickle cell anemia has rigid, sticky red blood shaped like sickles or crescent moons. These cells often get stuck in small blood vessels, which can slow or block blood flow and oxygen delivery to different parts of the body.
The sickle cell anemia trait is found on a recessive allele of the hemoglobin gene, while the regular red blood cell trait is found on the dominant allele. This means that a person must have two copies of the recessive allele (one from their mother and the other from their father) to be born with this condition. People who have one dominant and one recessive allele or both dominant alleles will have healthy red blood cells.
