Marfan Syndrome
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What is Marfan syndrome?
Marfan syndrome is a disorder of the connective tissue. Connective tissue provides strength and flexibility to structures throughout the body such as bones, ligaments, muscles, walls of blood vessels, and heart valves.
Marfan syndrome affects most organs and tissues, especially the skeleton, lungs, eyes, heart, and the large blood vessel that distributes blood from the heart to the rest of the body (the aorta). The signs and symptoms of Marfan syndrome vary widely in severity, timing of onset, and rate of progression. Affected individuals often are tall and lean, have elongated fingers and toes (arachnodactyly), and have an arm span that exceeds body height. Other common features include unusually flexible joints, a long and narrow face, a highly arched roof of the mouth and crowded teeth, an abnormal curvature of the spine (scoliosis), and either a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum). About half of people with Marfan syndrome have a dislocated lens (ectopia lentis) in one or both eyes, and most have some degree of nearsightedness (myopia). Clouding of the lens (cataract) may occur in mid adulthood, and increased pressure within the eye (glaucoma) occurs more frequently than in people without Marfan syndrome.
Most people with Marfan syndrome have abnormalities of the heart and the aorta. Leaks in valves that control blood flow through the heart can cause shortness of breath, fatigue, and an irregular heartbeat felt as skipped or extra beats (palpitations). If leakage occurs, it usually affects the mitral valve, which is a valve between two chambers of the heart, or the aortic valve that regulates blood flow from the heart into the aorta. The first few inches of the aorta can weaken and stretch, which may lead to a bulge in the blood vessel wall (an aneurysm). The increased size of the aorta may cause the aortic valve to leak, which can lead to a sudden tearing of the layers in the aorta wall (aortic dissection). Aortic aneurysm and dissection can be life threatening.
Marfan syndrome is sometimes classified as type I or type II, although this classification system is not universally accepted. When used, type I or classic Marfan syndrome refers to the most common form of this disorder, characterized by the features described above. Type II Marfan syndrome is less common. It is similar to classic Marfan syndrome except eye problems (such as ectopia lentis) are absent, and the genetic cause is different.
How common is Marfan syndrome?
Worldwide, Marfan syndrome affects at least 1 in 5,000 people.
What genes are related to Marfan syndrome?
Mutations in the FBN1 and TGFBR2 genes cause Marfan syndrome.
Mutations in the FBN1 gene cause classic Marfan syndrome. The FBN1 gene provides instructions for making a protein called fibrillin-1. Fibrillin-1 binds to itself and other proteins and molecules to form threadlike filaments called microfibrils. Microfibrils become part of the fibers that provide strength and flexibility to connective tissue. Additionally, microfibrils trap molecules called growth factors and release them at the appropriate time to control the growth and repair of tissues and organs throughout the body. A mutation in the FBN1 gene can reduce the amount and/or quality of fibrillin-1 that is available to form microfibrils. As a result, growth factors are released inappropriately, causing the characteristic features of Marfan syndrome.
Some researchers believe that a small percentage of Marfan syndrome cases are caused by mutations in the TGFBR2 gene. These cases are called Marfan syndrome type II. Other researchers believe that TGFBR2 mutations cause a disorder that may have some Marfan-like features but is not Marfan syndrome. The TGFBR2 gene provides instructions for making a protein that transmits signals from the cell surface to the nucleus. Through this signaling process, the environment outside the cell affects activities inside the cell such as division and growth. Mutations in the TGFBR2 gene alter the signaling activity of the protein, which disturbs the growth and development of connective tissue.
How do people inherit Marfan syndrome?
This condition is inherited in an autosomal dominant pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder.
At least 25 percent of classic Marfan syndrome cases result from a new mutation in the FBN1 gene. These cases occur in people with no history of the disorder in their family.
Source: National Institutes of Health
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Reports summarize Marfan syndrome study results from N.M. Sergienko and co-researchers
2009 JUN 15 - (NewsRx.com) -- According to a study from Kiev, Ukraine, "The authors present a patient with Marfan syndrome who underwent cataract surgery using a novel device for fixation of capsular bag. The capsule fixation device (CFD) is poly(methyl methacrylate) arch with double-armed bent hook that can be introduced into the anterior chamber through the clear corneal incision, placed with a rest on the capsule equator, and sutured to the sclera without injury of the capsular bag." "A 16-year-old patient with Marfan syndrome underwent consecutive phacoemulsification with in-the-bag intraocular lens and CFD implantation on both eyes. During the surgery handling the CFD was technically simple with good visualization. The preoperative best-corrected visual acuity was 0.3 and 0.1 and postoperatively 0.6 and 0.8 in the right and left eyes, respectively. The postoperative follow-up was over 9 months," wrote N.M. Sergienko and colleagues. The researchers concluded: "Use of the CFD was successful in a case of lens subluxation with no complications observed during the period of follow-up. (Eur J Ophthalmol 2009; 19:143-6)'." Sergienko and colleagues published the results of their research in European Journal of Ophthalmology (Capsule fixation device for cataract surgery. European Journal of Ophthalmology, 2009;19(1):143-146). For additional information, contact A.K. Yakimov, Eye Microsurg Center, Komarov Avenue 3, UA-03680 Kiev, Ukraine. The publisher of the European Journal of Ophthalmology can be contacted at: Wichtig Editore, 72, 74 Via Friuli, 20135 Milan, Italy. Keywords: Ukraine, Kiev, Cardiology, Genetics, Marfan Syndrome, Ophthalmology, Surgery. This article was prepared by Cardiovascular Week editors from staff and other reports. Copyright 2009, Cardiovascular Week via NewsRx.com.
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