A individual with sickle cell trait (one sickle cell gene) is born with sickle cell trait and will always have sickle cell trait. The same may be said with sickle cell disease (two sickle cell genes). Sickle cell disease causes sickness, but sickle cell trait does not. The severity of sickle cell disease varies with time. Some people are born with two damaged copies of the gene, others are born with one normal copy and one damaged copy, and still others are born with two healthy copies. Sickle cell disease affects people of African descent particularly in Africa and America. It is more common in individuals who are homozygous for the sickle cell allele (SS genotype). In other words, an individual must have two copies of the sickle cell allele to be affected by sickle cell disease. People with one copy of the sickle cell allele (AS or AA genotype) can develop a mild form of the disease known as sickle cell trait. Individuals with two copies of the normal hemoglobin gene (AA genotype) cannot get sickle cell disease because they do not have enough damaged genes to cause the disease. They would just have a very bad episode if they were to suffer a blood loss that could not be recovered from. People with one copy of the sickle cell gene and another genetic mutation sometimes develop severe disease. This occurs when people with two copies of the mutant gene (CC genotype) also carry one copy of the sickle cell gene (SS genotype).