FBN1 and Marfan syndrome: Marfan syndrome is a clinical diagnosis conferred to patients who meet the revised international criteria, with the majority having mutations in FBN1,which codes for a glycoprotein called fibrillin-1 (Figure 2).39 Without intervention, patients with Marfan syndrome have an average life expectancy of ≈40 years; 80% of mortality is related directly to aortic dilatation, dissection, and rupture.