Sickle cell disease affects the red blood cells and is one of the most common genetic (inherited) diseases. It affects 70 000 people in the United States. The normal red blood cell carries oxygen and delivers it to the tissues. Sickle-shaped red blood cells have difficulty traveling through the blood vessels to deliver oxygen to the tissues. These sickle cells are more stiff and can get stuck inside the blood vessels. People with sickle cell disease often have problems caused by blockages of these sickle cells within their blood vessels. Compared with normal red blood cells, sickle cells are more fragile and are often broken up within the blood vessels. When red blood cells are broken, the affected person becomes anemic (low blood count) and may develop a yellow discoloration in the whites of the eyes called jaundice. Pain is a major consequence of red blood cells sickling within the blood vessels. When pain is severe, it is called a sickle cell pain crisis. The contents of the sickle cell released during its breakage can damage the blood vessel wall, resulting in vasculopathy (disorder of the blood vessel wall that further restricts blood circulation to tissues or organs). The December 10, 2008, issue of JAMA includes an article about a person with sickle cell vasculopathy.