Article: Marfan syndrome

Marfan syndrome is a connective tissue disorder characterized by unusually long limbs. The disease also affects other bodily structures — including the lungs, eyes, heart and blood vessels — in less obvious ways. It is named for Antoine Marfan, the French pediatrician who first described it in 1896.

Marfan syndrome received great public attention when the musical RENT premiered in 1996. The day before the musical premiered off-Broadway, its writer, Jonathan Larson, died of an aortic dissection, which was determined to have been caused by Marfan syndrome.

Cause

Marfan syndrome is an autosomal dominant disorder that has been linked to the FBN1 gene on chromosome 15. FBN1 codes for a protein called fibrillin-1, which is essential for the formation of elastic fibers found in connective tissue. Marfan syndrome is also an example of a dominant negative mutation. Marfan syndrome is associated with incomplete penetrance, therefore not all persons carrying the mutation develop the disease. Without the structural support provided by fibrillin, many connective tissues are weakened, which can have severe consequences on support and stability. A related disease has been found in mice, and the study of mouse fibrillin synthesis and secretion, and connective tissue formation, has begun to further our understanding of Marfan syndrome in humans. For instance it has been found that simply reducing the level of normal fibrillin-1 causes the Marfan related disease in mice [1].

More recently, transforming growth factor β (TGFβ) has been shown to play an important role in Marfan syndrome. Fibrillin-1 binds TGFβ, inactivating it. In Marfan syndrome, reduced levels of fibrillin-1 allow TGFβ to damage the lungs and heart. New treatments for Marfan, using antagonists of TGFβ, are being investigated (Habashi et al., 2006 Science 312(5770):117-21).

Diagnosis

Although genetic testing is available, a diagnosis is usually made solely on clinical findings.

Epidemiology

Estimates indicate that perhaps 1 in 10,000 people (0.01 percent of the population) has Marfan syndrome. It affects all races and both sexes equally.

Most individuals with Marfan syndrome have another affected family member, but about 30 percent of cases are due to de novo genetic mutations. Genetic counseling is available for families who may be at risk for Marfan syndrome.

Symptoms

The most serious conditions associated with Marfan syndrome primarily involve the cardiovascular system. Marfan syndrome may cause leakage of the mitral or aortic valves that control the flow of blood through the heart. This may produce shortness of breath, an irregular pulse, and undue tiredness. Another complication is aortic aneurysm.

Marfan syndrome sufferers may grow to larger than normal height, and typically have long, slender limbs and fingers. Sometimes the fingers have a long, thin, spidery appearance known as arachnodactyly. In addition to affecting height and limb proportions, Marfan syndrome may produce other skeletal symptoms. Curvature of the spine (scoliosis) is a common problem, as is abnormal indentation (pectus excavatum) or protrusion (pectus carinatum) of the sternum. These symptoms may in turn cause unusual pressure on the heart and lungs. Other symptoms include; abnormal joint flexibility, high palates, flat feet, stooped shoulders, and dislocation of the optic lens.

Nearsightedness or myopia is a common condition associated with Marfan syndrome. In addition, the weakening of connective tissue often causes detachment of the retina and/or displacement of the lens in one or both eyes.[2]

Treatment

There is no cure for Marfan syndrome, but effective treatment allows many people with the disorder to live normally.

The heart conditions related to Marfan syndrome may not necessarily produce obvious symptoms. As a result, regular checkups by a cardiologist are needed to monitor cardiovascular health. Potential problems may be detected through echocardiography, which involves the use of ultrasound to study the heart valves and the aorta. Beta blockers have been used to control some of the complications such as aortic aneurysms. If the dilation of the aorta threatens to lead to rupture a composite aortic valve and graft may be implanted. Although aortic graft surgery is a serious undertaking it usually results in a good outcome and a satisfactory quality of life. Elective aortic valve/graft surgery is usually considered when aortic dilatation reaches 50 millimeters, but each case needs to be specifically evaluated by a qualified cardiologist. New valve-sparing surgical techniques are becoming more common. Rupture of the aorta, or aortic dissection, is the most common cause of sudden death among Marfan syndrome sufferers.

The skeletal and ocular manifestations of Marfan syndrome can also be serious, although not life-threatening. These symptoms are usually treated in the typical manner for the appropriate condition. This can also affect height, arm length, and life span.

The blood pressure drug losartan prevents aortic aneurysms and lung problems in a model organism mouse model of the disease. [3]

Famous people

Below is a list of prominent figures known or believed to have had Marfan syndrome (most are according to the U.S. National Marfan Foundation):

• Abraham Lincoln
• Vincent Schiavelli, actor
• Jonathan Larson, Tony Award-winning playwright (Rent)
• Flo Hyman, captain, U.S. Olympic Volleyball team, 1984 (silver medalist)
• Chris Patton, college basketball player (University of Maryland)
• Akhenaten, Egyptian pharaoh, who was possibly the father of King Tutankhamun
• Charles de Gaulle
• Sergei Rachmaninoff
• Niccolò Paganini
• Mary Queen of Scots
• John Tavener, composer
• (possibly) Johnny Appleseed
• (possibly) Peter Crouch, England and Liverpool footballer

Related disorders

• Bicuspid aortic valve with aortic vasodilation
• Congenital Contractural Arachnodactyly (CCA) or Beals Syndrome
• Cystic medial degeneration
• Ehlers-Danlos syndrome
• Familial aortic aneurysm
• Familial ectopia lentis (dislocated lens)
• Gigantism (or a Marfan body type)
• Homocystinuria
• Mitral valve prolapse
• Shprintzen-Goldberg Syndrome
• Stickler syndrome