Marfan's syndrome is a genetic (inherited) disorder that affects the body's connective tissue. Connective tissue is the tough, fibrous, elastic tissue that connects one part of the body with another. It is a major part of tendons, ligaments, bones, cartilage and the walls of large blood vessels. In Marfan's syndrome, the body can't produce enough fibrillin, an important building block of connective tissue.
The problem in Marfan's syndrome is caused by a mutation (change) in a gene. Genes are segments of DNA that direct the body to produce proteins. In many families with inherited Marfan's syndrome, the mutation affects the FBN1 gene on chromosome 15, although a second gene on chromosome 5 may be involved in some cases.
Because of the inherited problem producing fibrillin, people with Marfan's syndrome have from many different problems related to weakness in connective tissue. These problems include:
Reduced vision — In about 65 percent of Marfan's patients, the lens of the eye becomes dislocated because tiny eye ligaments that normally hold the lens in place are weak. This condition is called ectopia lentis. Marfan's syndrome also seems to increase the risk of myopia (nearsightedness), cataracts at an unusually early age (age 40 to 50), glaucoma, retinal detachment and strabismus.
Skeletal abnormalities — Patients with Marfan's syndrome are typically very tall, with long limbs and long, slender, spiderlike fingers. They also may have severe chest deformities, such as a chest that is either caved in or protrudes in front. Some patients also have scoliosis (curvature of the spine).
Cardiovascular changes — Weakened connective tissues affect the heart and blood vessels of people with Marfan's syndrome. Cardiovascular problems are the major cause of illness and death related to Marfan's syndrome. In people with Marfan's syndrome, connective tissue weakness can cause mitral valve prolapse (a "floppy" mitral valve that doesn't close properly) or mitral valve regurgitation (a severe problem in closing the mitral valve that results in a significant backflow of blood into the left atrium). It also can lead to an abnormal swelling or dilatation (aneurysm) in the heart's main artery, the aorta, typically at the root of the aorta where it leaves the heart. This aneurysm can lead to aortic regurgitation (abnormal backflow of blood when the heart tries to pump blood forward), aortic dissection (a spreading tear in the inner wall of the aorta that causes a separation between the aorta's inner and outer layers) and aortic rupture (a break in the wall of the aorta, with leakage of blood).
Health experts estimate that about 200,000 people in the United States have Marfan's or related syndromes, and the disorder probably affects one out of every 10,000 newborns.