• Severe scoliosis. About half the people with Marfan syndrome develop scoliosis, a condition in which the bones of the spine (vertebrae) twist into an S or C shape. The spinal curvature is measured by the angle between the vertebrae as seen on an X-ray and is expressed in degrees. The curve can occur in your upper or lower spine and may be relatively slight — less than 20 degrees — or large (more than 70 degrees). When the curve is severe, your rib cage may press against your lungs, making it difficult to breathe. A curve greater than 100 degrees can impair the function of your heart and lungs and increase your risk of pneumonia and other lung infections. Scoliosis also puts you at higher risk of bone loss (osteoporosis), chronic back pain, and inflammation and arthritis of the spine (spondylosis). What's more, having to wear a brace during childhood and adolescence — a standard treatment for severe scoliosis — may lead to feelings of self-consciousness and social isolation.

• Spondylolisthesis. This occurs when one vertebra slips forward over another, often near the end of your spine. Anyone can develop spondylolisthesis, but it's much more common in people with Marfan syndrome. Although it usually doesn't cause permanent damage, spondylolisthesis can lead to back pain and stiffness.
• Foot pain. People with Marfan syndrome often have long, slender feet with arches that are flatter than normal. Because the feet are delicate, they're not able to withstand the ordinary stresses placed on them, which may lead to chronic foot pain. This can usually be helped by using special cushions, inserts or orthotics and by wearing comfortable, low-heeled shoes.

Marfan syndrome may cause other signs and symptoms, such as:

• Stretch marks. These pink or reddish streaks in your skin usually occur during pregnancy or after a rapid loss of weight. But people with Marfan syndrome often develop stretch marks simply because their skin lacks the internal structure to keep it resilient. The streaks frequently develop in areas of stress such as your shoulders, hips and low back. Although they may be a cosmetic concern, stretch marks are harmless and often fade over time.
• Dural ectasia. Your brain and spinal cord are surrounded by fluid that's enclosed by a membrane (dura) composed of connective tissue. Marfan syndrome can cause the dura to weaken and stretch (dural ectasia) especially as you grow older. In time, the membrane may press on the vertebrae in your lower spine. You may not always be aware that this has occurred, or you may have symptoms that range from a mild aching in your lower back near your tailbone to abdominal pain, headache, and pain or numbness in your legs