Ascending aortic aneurysm with or without features of Marfan syndrome and other fibrillinopathies: new insights.

More than 70 unique fibrillin-1 mutations have been identified in individuals with a variety of phenotypic changes. These range from severe neonatal lethal forms of Marfan syndrome to adult onset manifestations, mitral valve prolapse syndromes to isolated features such as ectopia lentis, Marfanoid body habitus and ascending aortic aneurysm and/or dissection. Fibrillin-1 mutations result in structurally and functionally defective fibrillin-1 molecules and microfibrils. Recent molecular genetic and fibrillin-1 biosynthesis studies suggest that individuals with fibrillin-1 abnormalities can be further subdivided into groups that are associated with distinct differences in severity and prognosis. In recognition of the expanding scope of related connective tissue disorders, we propose the terms microfibrillar disorder for disorders affecting fibrillin-containing microfibrils, and the more narrow concept of fibrillinopathy for clinical entities associated with abnormalities of fibrillin-1 or fibrillin-2. This latter category includes the previously defined disorders Marfan syndrome, congenital contractual arachnodactyly, and forms of ascending aortic aneurysm and/or dissection.