Sickle cell anemia is a genetic blood disorder caused by a mutation in the gene for hemoglobin. In 1904, Dr. James Herrick first observed sickle-shaped red blood cells in an African American patient, which led to the discovery and naming of the disease. The mutation causes hemoglobin to form rigid sickle shapes under low oxygen conditions, which can block blood flow and damage organs. Individuals with two copies of the mutation experience symptoms while carriers with one copy are resistant to malaria.