Causes. The deformed red blood cells in sickle cell anemia are the way they are because the hemoglobin they carry is abnormal. The abnormality is caused by a mutation in the hemoglobin beta gene, which is inherited from both of the person’s parents if they have sickle cell anemia. If only one of the parents has the abnormal gene, the child can be a carrier but will most often not have the disease itself. This person is said to have sickle cell trait. However, there are exceptions to this. A person can inherit the abnormal hemoglobin beta gene from one parent but get another type of mutated gene from their other parent. This can cause other maladies such as sickle cell hemoglobin C anemia. Some people with only one mutated gene can still have symptoms.