Marfan Syndrome

Sunday, May 1, 2011

Marfan syndrome is a genetic condition that affects the connective tissue. In the Marfan syndrome, the chemical structure of the connective tissue is abnormally altered, and as a consequence many of these structures are not as stiff as they should be. Connective tissue provides substance and support to tendons, ligaments, blood vessel walls, cartilage, heart valves and many other structures. The Marfan syndrome has a range of expressions, from mild to severe. The most serious complications are defects of the heart valves and aorta. It may also affect the lungs, eyes, the dural sac surrounding the spinal cord, skeleton and the hard palate. So, a person with Marfan syndrome may exhibit long limbs and spider-like fingers, chest abnormalities, curvature of the spine and a particular set of facial features including a highly arched palate, and crowded teeth.

Transmitted as an autosomal dominant trait, the Marfan syndrome is caused by defects in a gene called fibrillin-1. Fibrillin-1 plays an important role as the building block for elastic tissue in the body. The gene defect also causes too much growth of the long bones of the body. This causes the tall height and long arms and legs seen in people with this syndrome. In addition to being a connective protein that forms the structural support for tissues outside the cell, the normal fibrillin-1 protein binds to another protein, transforming growth factor beta (TGF-ß). TGF-ß has deleterious effects on vascular smooth muscle development and the integrity of the extracellular matrix. In the Marfan syndrome, the walls of the major arteries are weakened. The aorta, the major artery that leaves the heart, often is affected. When this occurs, it gets bigger (dilates), which can weaken the inner aortic wall. Under strenuous exertion, the aorta wall can tear. Blood can leak through these tears into the aortic wall, separating its layers, which is a process called aortic dissection. The Marfan syndrome can involve any of the four heart valves. The two most important ones, however, are the mitral and aortic valves. Blood may leak backward through a valve, increasing the heart's workload. As a result, over time the heart may enlarge.

Treatment

Medicine to slow the heart rate may help prevent stress on the aorta. Avoid participating in competitive athletics and contact sports to avoid injuring the heart. Some people may need surgical replacement of the aortic root and valve. People with Marfan syndrome should take antibiotics before dental procedures to prevent endocarditis. Pregnant women with Marfan syndrome must be monitored very closely because of the increased stress on the heart and aorta.