What does it Cause it?

A genetic problem causes sickle cell anemia. People with the disease are born with two sickle cell genes, one from each parent. If you only have one sickle cell gene, it's called sickle cell trait

Sickle cell anemia is caused by an error in a gene that makes the beta globin chain of hemoglobin. The resultant abnormal hemoglobin (sickle hemoglobin) deforms the red blood cells when they are under low oxygen conditions. Children who inherit 2 copies of the sickle gene, one from each parent, have sickle cell anemia. Children who inherit the sickle gene from only one parent do not have the disease, but will carry the sickle cell trait. Individuals with sickle cell trait generally have no symptoms. About 2 million Americans (or 1 in 12 African-Americans) carry the sickle gene(medicine.net, 2011)