Genetic and Pediatric Diseases · USMLE Step 1

Marfan syndrome commonly results from mutations in the FBN1 gene. Which tissue abnormality primarily accounts for its characteristic aortic aneurysm risk?

  1. Defective collagen cross-linking in the aorta
  2. Defective fibrillin-1 weakening aortic elastic fibers
  3. Excess mucopolysaccharide deposition in vessel walls
  4. Hyperplasia of smooth muscle in the aortic wall
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Correct answer: Defective fibrillin-1 weakening aortic elastic fibers

FBN1 mutations impair production of fibrillin-1, a structural component of elastic fibers; weakened elastic fibers in the aortic wall predispose to aortic aneurysm and dissection in Marfan syndrome.

Difficulty: Medium Question 9 of 20

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