The primary objective of this study is to determine whether increased quantitites of circulating microfibril fragments, measured with a simple blood test, are associated with aortic root size and increased growth of the aortic root in Marfan syndrome and related disorders. The secondary objectives of this study are to: (1) Determine a Marfan "signature" profile of circulating microfibril fragments. (2) Determine if high concentrations of fibrillin-1 fragments are associated with large aortic root diameters. (3) Determine which fibrillin-1 fragments are good biomarkers for aortic root growth and size in Marfan syndrome. (4) Determine the relation between fibrillin-1, aortic root diameter, and medical and lifestyle factors reported on questionnaires.