Following recent implication of transforming growth factor β (TGF-β) in the etiology of MFS, that FBN1 in disease pathology has expanded from mere defective structural support to regulatory dysfunction in cellular signaling: The regulatory role of FBN1, and the implication of increased TGF-β signaling in the development of some manifestations of the disease such as impaired pulmonary alveolar septation or myxomatous thickening of mitral valve.30Clinical manifestation:Tall slender stature with relatively long legs and arms, long hands, and long fingers. The gene discussed is FBN1; the disease is Marfan syndrome.