Raynaud syndrome, also known as Raynaud's phenomenon disease is a rare disorder of the blood vessels, usually in the fingers and toes. It causes the blood vessels to narrow when you are cold or feeling stressed. When this happens, blood can't get to the surface of the skin and the affected areas turn white and blue. When the blood flow returns, the skin turns red and throbs or tingles. In severe cases, loss of blood flow can cause sores or tissue death.