Marfan syndrome (MFS) is a genetic disorder of the connective tissue. The degree to which people are affected varies. People with Marfan tend to be tall and thin, with long arms, legs, fingers and toes. They also typically have flexible joints and scoliosis. The most serious complications involve the heart and aorta, with an increased risk of mitral valve prolapse and aortic aneurysm. Other commonly affected areas include the lungs, eyes, bones and the covering of the spinal cord.