The genes exist on structures inside cells called chromosomes. Other characteristics are determined by one gene pair. The genes involved in sickle cell disease control the production of a protein in red cells called hemoglobin . Hemoglobin binds oxygen in the lungs and delivers it to the peripheral tissues, such as the liver and muscles. Most people have two normal genes for hemoglobin.
Some people carry one normal gene and one gene for sickle hemoglobin.
These people are normal in almost all respects. People with sickle cell trait do not develop sickle cell disease as they grow older. People with sickle cell trait rarely develop problems related to their single sickle cell gene, and then only under very unusual conditions. A person receives the sickle cell genes or not only at the time of conception. Therefore, neither sickle cell trait nor sickle cell disease can be contracted.