Marfan Syndrome Essay

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Marfan syndrome (also called Marfan’s syndrome) is a genetic disorder of the connective tissue. People with Marfan’s tend to be unusually tall, with long limbs and long thin fingers. Marfan syndrome is a type of mutation that has a negative effect in humans. It is inherited as a dominant trait. It is carried by a gene called FBN1, which encodes a connective protein called fibrillin-1. People have a pair of FBN1 genes and because it is dominant, people who have inherited one affected FBN1 gene from either parent will have Marfan. 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. Microfibrils are found in the extracellular matrix of connective tissue and give it its long-range elasticity. Their main component is fibrillin, the protein that is defective in Marfan syndrome. Fibrillin is encoded by the FBN1 gene on chromosome 15. This consists of 66 exons spread over 235 kb of genomic DNA. The spliced mRNA is 9749 nt long. When ribosomes start translating the mRNA the first 27 amino acids produced (the signal peptide) bind to the endoplasmic reticulum. The 2781 amino acid polypeptide is then injected into the lumen of the endoplasmic reticulum as it is synthesized. Here the signal peptide is cleaved off, the chain folds into more than 50 structural domains, each held together by multiple S–S bridges between cysteine residues and sugars are attached to 14 asparagine residues. This protein is exported as single molecules, or possibly dimers. Once outside the cell, fibrillin molecules are assembled and cross-linked in specific ways to form microfibrils, large structures that appear under the electron microscope as a string of beads. Each bead consists of folded cross-linked

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