Sickle Cell Anemia

Autosomal recessive disorder in which hemoglobin A is partly or completely replaced with abnormal sickle hemoglobin S. When exposed to a decrease in oxygen, hemoglobin S becomes viscous, causing the red cells to become crescent-shaped (sickled), rigid, sticky, and fragile. When sickled, red blood cells clump together impeding circulation to the capillaries, resulting in obstruction, tissue hypoxia, and further sickling.