Sickle cell anemia is a genetic blood disorder that affects red blood cells. It is most common among those of African descent. The disease causes red blood cells to become rigid and sickle-shaped, which can cause anemia, pain crises, and other serious complications. Symptoms vary from person to person but often include fatigue, shortness of breath, and pain. The disease is inherited when both parents carry the sickle cell trait, resulting in a 25% chance their child will have the disease.