What happens in a blood sample of individuals who carry the sickle cell allele when the blood is deprived of oxygen?

When individuals who carry the sickle cell allele experience low oxygen levels, their red blood cells can become deformed and take on a sickle shape. This occurs because the abnormal hemoglobin (hemoglobin S) polymerizes under low oxygen conditions, causing the cells to become rigid and sticky. As a result, these sickle-shaped cells can block small blood vessels, leading to reduced blood flow and potential pain crises, as well as increased risk of complications like infections and organ damage.