Marfan Syndrome
Marfan syndrome is a rare disorder of connective tissue, resulting in abnormalities of the eyes, bones, heart, and blood vessels.
In Marfan syndrome, which is caused by a dominant gene, some fibers and other parts of connective tissue undergo changes that ultimately weaken the tissue. The weakening affects bones and joints as well as internal structures, such as the heart, blood vessels, eyes, and intestines. Weakened tissues stretch, distort, and can even tear. For example, the aorta may weaken, bulge, or tear. Connective tissues that join structures may weaken or break, separating formerly attached structures. For example, the eye's lens or retina may separate from its normal attachments.
Symptoms can range from mild to severe. Many people with Marfan syndrome never notice symptoms. In some people, symptoms may not become apparent until adulthood. People with Marfan syndrome are taller than expected for their age and family. Their arm span (the distance between fingertips when the arms are outstretched) is greater than their height. Their fingers are long and thin. Often, the breastbone (sternum) is deformed and pushed either outward or inward. The joints may be very flexible. Flat feet and a humpback with an abnormal curve of the spine (kyphoscoliosis) are common; so are hernias. Usually, the person has little fat under the skin. The roof of the mouth is often high.
The most dangerous complications develop in the heart and lungs. Weakness may develop in the connective tissue of the wall of the body's main artery, the aorta. The weakened wall may result in blood seeping between the layers of the aorta's wall (aortic dissection) or a bulge (aneurysm), which can rupture (see Section 3, Chapter 35). Pregnancy increases the risk of dissection. Delivery by caesarean section is often recommended to minimize the risk.
If the aorta gradually widens, the aortic valve, which leads from the heart into the aorta, may begin to leak (aortic regurgitation). The mitral valve, which is located between the left atrium and ventricle, may leak or become prolapsed (bulge backward into the left atrium (see Section 3, Chapter 28)). These heart valve abnormalities can impair the heart's ability to pump blood. Abnormal heart valves can also develop serious infections (infective endocarditis). Air-filled sacs (cysts) may develop in the lungs. The cysts may rupture, bringing air into the space that surrounds the lungs (pneumothorax (see Section 4, Chapter 52)).
The lens of one or both eyes may be displaced in Marfan syndrome. The light-sensitive area at the back of the eye (retina) may detach from the rest of the eye. Displacement of the lens and detachment of the retina may cause permanent loss of vision.
Doctors may suspect the diagnosis if an unusually tall, thin person has any of the characteristic symptoms, or if Marfan syndrome has been recognized in other family members.
It is most important for doctors to monitor for complications that can cause serious symptoms. Echocardiography is used to evaluate the heart and aorta and is usually repeated yearly. The eyes are usually examined yearly. Echocardiography and eye examinations are also performed whenever symptoms develop.
Treatment and Prognosis
There is no cure for Marfan syndrome nor any way to correct the abnormalities in the connective tissue. Treatment is aimed at fixing abnormalities before dangerous complications develop. Some doctors prescribe drugs, such as beta-blockers, that make blood flow more gently through the aorta. However, whether these drugs help is controversial. If the aorta has widened or developed an aneurysm, the affected section can be repaired or replaced surgically. A displaced lens or retina can usually be reattached surgically.
Years ago, most people with Marfan syndrome died in their 40s. Now, most people with Marfan syndrome live until their 60s. Prevention of aortic dissection and rupture probably explains why the life span has been lengthened.
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