Surgery>>>>>Thoracic Aneurysms and Aortic Dissection
Question 4#

Marfan syndrome is caused by an abnormality in which of the following proteins? 

a. Elastin
b. Metalloproteinase
c. Collagen
d. Fibrillin

Correct Answer is D


Marfan syndrome is an autosomal-dominant genetic disorder characterized by a specific connective tissue defect that leads to aneurysm formation. The phenotype of patients with Marfan syndrome typically includes a tall stature, high palate, joint hypermobility, eye lens disorders, mitral valve prolapse, and aortic aneurysms. The aortic wall is weakened by fragmentation of elastic fibers and deposition of extensive amounts of mucopolysaccharides (a process previously called cystic medial degeneration or cystic medial necrosis). Patients with Marfan syndrome have a mutation in the fibrillin gene located on the long arm of chromosome 15. The traditionally held view is that abnormal fibrillin in the extracellular matrix decreases connective tissue strength in the aortic wall and produces abnormal elasticity, which predisposes the aorta to dilatation from wall tension caused by left ventricular ejection impulses. More recent evidence, however, shows that the abnormal fibrillin causes degeneration of the aortic wall matrix by increasing the activity of transforming growth factor-beta (TGF-β). Between 75 and 85% of patients with Marfan syndrome have dilatation of the ascending aorta and annuloaortic ectasia (dilatation of the aortic sinuses and annulus). Such aortic abnormalities are the most common cause of death among patients with Marfan syndrome. Marfan syndrome also is frequently associated with aortic dissection.