![]() ![]() Researchers are still working to understand how specific versions of protein cause the varied characteristics seen among individuals who have Marfan syndrome. Depending on how fibrillin-1 proteins are altered, different jobs are disrupted. Microfibrils do different jobs in different tissues, and they interact with many other proteins. Some microfibrils don't store TGF-β, which affects the development of bones and muscle. ![]() In others, the proteins don't wrap around elastin very well, and elastic microfibrils don't stretch properly. In some cases, the microfibrils are weak or disorganized. The altered and healthy fibrillin-1 combine to make microfibrils that do not do their job properly. ![]() This altered protein interferes with the healthy fibrillin-1 protein. These FBN1 alleles code for fibrillin-1 protein that has an altered structure. There are fewer microfibrils, and the connective tissue that relies on them is weak. The fibrillin-1 protein that cells make from the one healthy allele is still made into microfibrils. Having any of these alleles causes Marfan syndrome. A third type of allele codes for fibrillin-1 protein that is released from the cell, but the protein cannot be used as building blocks to make microfibrils. With other alleles, cells make plenty of fibrillin-1 protein, but they don't release the non-working protein to the outside. In the simplest cases, cells make too little fibrillin-1 protein. Multiple FBN1 alleles fall into this category. In others, the non-working protein is made into microfibrils, but the microfibrils do not work well. In some people, the non-working protein can't be used, and they have too few microfibrils. Non-working fibrillin-1 protein can cause Marfan syndrome in two main ways. They make some fibrillin-1 protein that works, and some that doesn't. People with Marfan syndrome generally have one healthy and one disease-causing allele. But, when people are diagnosed and treated early, there is a good chance for preventing the most serious effects.Įach person has two versions (alleles) of the FBN1 gene, and both code for fibrillin-1 protein. Effects on the aorta are very common in Marfan syndrome. The high pressure of blood leaving the heart can weaken the aorta over time, causing it to bulge, or even tear. When microfibrils don't function normally, the aorta isn't as strong or elastic as it should be. The most serious effects involve the aorta, the main artery that moves blood from the heart to the rest of the body. Some people have heart complications, such as leaky valves. Lungs may collapse or detach from the chest wall. People with Marfan syndrome are at high risk for lung problems. The most dangerous effects of Marfan syndrome are harder to see. Observable traits in people with Marfan syndrome can include the following: Others can have life-threatening complications. Some people with Marfan syndrome experience only mild symptoms. The effects of Marfan syndrome can be very different from person to person. This is one reason people with Marfan syndrome tend to be tall and thin. ![]() When microfibrils do not form properly, TGF-β can act in the wrong places or at the wrong times, affecting a person's growth and development. TGF-β helps to control muscle and bone growth. One such protein is TGF-β (transforming growth factor beta). They store other proteins, keeping them inactive until they're needed. Many fibrillin-1 microfibrils have a second job. People are often very flexible, and prone to dislocating knee, hip, and shoulder joints. The connective tissue holding joints together is too stretchy. This is why people with Marfan syndrome usually have effects in their skeletal system. Flexible tissues are weak and lose their shape easily. With less working fibrillin-1, both types of microfibrils are disorganized or fragmented. They provide structure in rigid tissues like bones and tendons. Non-elastic microfibrils are made up mainly of fibrillin-1 alone. In these tissues, chains of fibrillin-1 protein wrap around another protein called elastin. In different tissues, fibrillin-1 is used to build two types of microfibrils: flexible and non-elastic.įlexible microfibrils are important in tissues that expand and contract, like blood vessels, lungs, and skin. Fibrillin-1 protein is the main building block of microfibrils - long, thread-like structures within connective tissue. ![]()
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