Marfan syndrome

Marfan's syndrome is a connective tissue disease with an autosomal dominant inheritance and an estimated prevalence in Europe of 3 in 10,000 (1)

People with Marfan's syndrome used to have a life expectancy reduced by 50% but this has changed because of improved treatment of cardiovascular abnormalities.

Typical musculoskeletal features include limbs disproportionately long for the trunk, scoliosis (in particular pectus excavatum or carinatum), and a high-arched narrow palate with laxity of the joints. (2)

• cardiovascular features are the most important diagnostically, with mitral valve prolapse and, particularly, dilatation of the ascending aorta
• aortic regurgitation may develop. Histologically, the aorta demonstrates cystic medial necrosis. Progressive dilatation of the aorta is symmetric, commencing at the sinus of Valsalva and predisposing to rupture and dissection
• subluxation of the lens because of laxity of the suspensory ciliary ligament is present in about 60% of cases, normally bilateral and presenting and associated with severe myopia because of increased axial length of the cornea from childhood onwards

The diagnosis of Marfan's syndrome is established in accordance with a review of the diagnostic criteria, known as the Ghent nosology, through a comprehensive assessment largely based on a combination of major and minor clinical manifestations in various organ systems and the family history. (3)

The pathogenesis of Marfan's syndrome has not been fully elucidated

• fibrillin-1 gene mutations are believed to exert a dominant negative effect
• Marfan's syndrome is termed a fibrillinopathy, along with other connective tissue disorders with subtle differences in clinical manifestations (4)

Treatment may include:

• prophylactic beta - blockers and angiotensin II-receptor blockers (ARBs) in order to slow down the dilation of the ascending aorta, and prophylactic aortic surgery
  • beta-blocker therapy may reduce TGF-beta activation, which has been recognized as a contributory factor in Marfan's syndrome (5)
  • ARBS in Marfan's syndrome
    • a meta-analysis of 7 trials (n=1442) found ARBs reduced the rate of increase of the aortic root Z score by about one half (mean annual increase 0.07 ARB vs 0.13 control; absolute difference -0.07 [95% CI -0·12 to -0.01]; p=0.012), including among those taking a beta blocker (6)
      • suggested that angiotensin receptor blockade (which attenuates TGF- beta activity) and this may be the mechanism that slows aortic root growth in Marfan syndrome
      • ARBs were effective even among those already taking a beta blocker
      • estimated effect of ARBs was significantly greater among those with a pathogenic variant in fibrillin-1, than those without such a fibrillin-1 variant, providing biological support for the effect
      • beta blockers were estimated to have a similar beneficial effect as ARBs

Détaint et al (7) reported that, by the age of 60 years, approximately 100% of patients with MF syndrome will have developed aortic root dilatation at varying degrees and three quarters of them would have undergone aortic root replacement on the basis of increased aortic diameter to critical levels and/or symptomatic aortic valve insufficiency (or Stanford type “A” dissection)

References:

1. Arslan-Kirchner M, Arbustini E, Boileau C, et al. Clinical utility gene card for: Marfan syndrome type 1 and related phenotypes [FBN1]. Eur J Hum Genet. 2010 Sep;18(9).
2. Tinkle BT, Lacro RV, Burke LW, et al. Health supervision for children and adolescents with Marfan syndrome. Pediatrics. 2023 Apr 1;151(4)
3. Dietz HC, Braverman AC, et al. The revised Ghent nosology for the Marfan syndrome. J Med Genet. 2010 Jul;47(7):476-85.
4. Gillis E, Kempers M, Salemink S, et al. An FBN1 deep intronic mutation in a familial case of Marfan syndrome: an explanation for genetically unsolved cases? Hum Mutat. 2014 May;35(5):571-4
5. Yuan SM, Jing H. Marfan's syndrome: an overview. Sao Paulo Med J. 2010 Dec;128(6):360-6
6. The Marfan Treatment Trialists' Collaboration. Angiotensin receptor blockers and beta blockers in Marfan syndrome: an individual patient data meta-analysis of randomised trials. Lancet August 29th 2022.
7. Détaint D, Faivre L, Collod-Beroud G, et al. Cardiovascular manifestations in men and women carrying a FBN1 mutation. Eur Heart J. 2010;31(18):2223–222