Raynaud’s disease or syndrome is a disorder of blood circulation, mainly in the fingers and toes. It is of unknown cause and characterized by changes of the skin that are aggravated by exposure to cold: first, becoming white with numbness and pain as a result of inadequate oxygenation of the blood, then red/purple with a burning sensation. The sudden constriction of blood vessels causes decreased blood flow to the extremities and can, in extreme cases, lead to gangrene. Also called “white finger”, “wax finger” or “dead finger”.