Thoracic aortic aneurysms are classically seen in which syndrome?

• A. Turner syndrome
• B. Down syndrome
• C. Marfan syndrome
• D. Ehlers-Danlos syndrome

Answer: (C)

Thoracic aortic aneurysms arise when the media of the aorta is weakened. In Marfan syndrome, a mutation in FBN1 leads to defective fibrillin-1, which disrupts elastic fiber formation and causes cystic medial degeneration. This weakens the aortic wall, especially the aortic root and ascending aorta, promoting dilation and increasing the risk of aneurysm and dissection. The systemic features of Marfan—tall stature with long limbs and fingers, scoliosis, chest wall deformities, and often lens dislocation—reflect the pervasive connective tissue fragility that also affects the aorta. While other connective tissue disorders can involve the aorta, the classic association taught is Marfan syndrome. Turner syndrome, Down syndrome, and Ehlers-Danlos have their own characteristic cardiovascular issues and are not the textbook pairing for thoracic aortic aneurysm.