In Marfan syndrome, which cardiac abnormality is most characteristic?

• A. Aorta
• B. Mitral valve prolapse
• C. Pulmonary hypertension
• D. Atrial septal defect

Answer: (C)

In Marfan syndrome, the defining cardiovascular issue is dilation of the aortic root (ascending aorta) caused by connective-tissue weakness and cystic medial degeneration. This aortic root dilation increases the risk of aortic aneurysm and dissection and dictates surveillance and management. Mitral valve prolapse can occur as well because valve tissue is affected, but it is not the hallmark feature. Pulmonary hypertension and atrial septal defects are not characteristic manifestations of Marfan syndrome and do not define its cardiac involvement.