The marfan syndrome

The Marfan syndrome is an inherited, autosomal-dominant disorder that affects the skeletal, ocular, and cardiovascular systems. The principle phenotypic characteristics are long bone overgrowth, ectopia lentis, and aortic root dilatation with premature death resulting from the rupture of aortic aneurysms. Recent biochemical and genetic studies have demonstrated that this deadly genetic disorder arises from defects in the gene of the connective tissue protein fibrillin. Fribrillin is a component of elastic microfibrils, structures found in the extracellular matrices of most tissues, including blood vessels, cartilage, tendons, skin, and the ciliary zonules. The appearance of microfibrils in the matrix produced by Marfan patient fibroblasts is different form that of normal cells. Immunofluorescent labeling of the matrix deposited by patient cells in culture is diminished in most cases, suggesting a deficit of normal fibrillin in the extracellular matrix of affected individuals. Most significantly, the involvement of fibrillin has been verified at the molecular level following the cloning and characterization of the fibrillin gene. Genetic linkage between the fibrillin gene and the Marfan phenotype has been established and the gene mapped to the same chromosomal position as the disease locus. In addition, a number of disease-associated mutations have been identified in fibrillin cause the Marfan syndrome.