A rare disorder that causes the blood vessels to become inflamed. Symptoms include sores in the mouth and on the sex organs and other skin problems, inflammation in parts of the eye, and pain, swelling, and stiffness of the joints. Other serious symptoms include blood clots, blindness, and inflammation of the brain, spinal cord, and digestive system. The symptoms may come and go on their own. Behcet syndrome is most common in young adults and its cause is unknown. Also called Behcet disease.