Hemoglobin Genetics
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) shapes.
Normally, a person inherits two copies of the gene that produces beta-globin, a protein needed to produce normal hemoglobin (hemoglobin A, genotype AA). A person with sickle cell trait inherits one normal gene and one abnormal gene encoding hemoglobin S (hemoglobin genotype AS).
Read more about this topic: Sickle Cell Trait