Which is the main distinguishing factor between Ehler's Danlos and Marfan syndromes?

• A. Skeletal involvement
• B. Gender
• C. Increased risk for aneurysms
• D. Prognosis

Answer: (A)

The main distinction lies in which body systems show the most characteristic changes. Marfan syndrome tends to produce clear skeletal features—tall stature with long, slender limbs, arachnodactyly (long fingers), chest wall deformities, scoliosis, and joint hypermobility. Ehlers-Danlos syndrome, on the other hand, is defined more by skin and connective-tissue problems—hyperextensible, fragile skin, easy bruising, and joint laxity—without the same prominent skeletal frame abnormalities. Because Marfan’s hallmark phenotype includes these noticeable skeletal findings, skeletal involvement is the most distinguishing feature when comparing the two.

The other options aren’t as helpful for differentiation. Gender isn’t a distinguishing factor, and while Marfan does carry a risk of aortic root dilation and aneurysm, that vascular risk isn’t exclusive to Marfan and vascular EDS can have arterial issues too. Prognosis varies by subtype in both disorders, so it isn’t a reliable distinguishing trait.