Marfan syndrome

Background

• Marfan syndrome (MFS) is a heritable connective tissue disorder with multi-system involvement
  • First described by Antoine Marfan in 1896
  • Clinical features vary along a spectrum typical of autosomal-dominant disorders

• Autosomal-dominant mutation in FBN1 gene (encoding fibrillin-1) on chromosome 15
  • This results in cystic medial degeneration of the aortic tunica media (leading to increased risk of aortic aneurysm / dissection)
  • This also interferes with elastin deposition during extracellular matrix formation implicates in the elasticity of multiple tissue types
  • Majority of cases (75%) are familial / inherited vs. minority (25%) are de novo mutations

• Estimated prevalence of 1/5000 individuals worldwide (equal between men and women)

• Life expectancy for those diagnosed and treated is now close to that of non-MFS population (previously expected increase in patient mortality by third and fourth decades of life)

Clinical Features (not all may be present)

• Tall stature, long extremities
• Reduce upper-to-lower segment ratio, increased arm span-to-height ratio
• Arachnodactyly (“wrist sign, thumb sign), reduced elbow extension
• Scoliosis or thoracolumbar kyphosis
• Pectus excavatum or carinatum
• Ligamentous laxity, hyperextensibility
• Protrusio acetabuli
• Hindfoot deformity, plain flat foot
• Ectopia lentis
• Myopia (often severe); retinal detachment
• Lumbrosacral dural ectasia
• Dolichocephaly, downward slanting palpebral fissures, enophthalmos, retrognathia, malar hypoplasia, high arched palate
• Skin striae

Increased risk of:

• Acute Aortic Syndrome (AAS)
  • Thoracic aortic aneurysm
  • [thoracic aortic dissection|Stanford Types A and B Aortic Dissection]
  • Intramural Hemotoma (IMH)
• Mitral valve prolapse (present in up to 60%) and mitral regurgitation
• Spontaneous pneumothorax (associated with bullae, 4-11%)
• Subarachnoid hemorrhage (SAH)
  • Controversial link between Marfan Syndrome and intracranial aneurysms (more clearly associated with vEDS and LDS)
• Ocular Lens dislocation, retinal detachment
• Spinal conditions (scoliosis; lumbosacral disease; dural ectasia)
• Musculoskeletal injuries due to joint laxity (laxity in 85% of children, 56% of adults)
• Complications during pregnancy (risk of aortic dissection)
  • Type A dissection risk increases with aortic dilation; Type B risk poorly understood. (aortic dissection in up to 4.5%, primarily peripartum)