Behçet's disease is an autoimmune disorder that affects multiple areas of the body. It commonly causes painful sores to form on mucus membranes in the mouth, eyes, anus and vagina. It can also cause inflammation and damage to the eyes and arthritis; less commonly it can also cause inflammation of the brain and spinal cord, blood clots, aneurysms, blindness and death. The cause is unknown but it is believed to be at least partly genetic and is treated using corticosteroids and immune suppressants.