Marfan syndrome (MFS) is a hereditary connective tissue disorder. Studies of MFS have established the critical contribution of fibrillin-1 deficiency to disease progression through altered cell-matrix interactions and dysregulated TGF-ß signalling. It is now known that the disease is caused by altered regulation of TGF-ß. As a result, the definition of MFS- and MFS-related diseases as the prototypical structural disorder of the connective tissue has changed to that of a developmental abnormality with broad and complex effects on the morphogenesis and tissue remodelling.