Sickle Cell Anemia One of the worst genetically inherited diseases is sickle cell anemia. Sickle cell anemia is an inherited blood disorder that occurs when you inherit a hemoglobin S gene from both of your parents. Inheriting one hemoglobin S gene and one normal hemoglobin gene means that you only have the trait, and not the disease. Sickle cell anemia causes chronically low levels of hemoglobin (the blood’s oxygen-carrying chemical) and episodes of extreme pain. People with sickle cell anemia have inherited genes for a type of hemoglobin that forms long rods when it gives up its oxygen. These hemoglobin rods, located inside the body’s typically disc-shaped red blood cell