A disorder is called cyanosis when the skin has a bluish tint (the color cyan got its name from a shade of blue). It is a sign of less oxygenated blood. It can be localized, especially at the extremities (fingers, toes) as in Raynaud's disease, or more widespread as in shock or chronic respiratory failure. Generalized cyanosis is often the symptom of a serious disease as is the case with adults with severe lung diseases which prevent proper blood oxygenation. It may also occur at birth as in Fallot's tetralogy, a genetic malformation of the cardiac system requiring prompt surgical care.