Review Question - QID 4448

Figure B shows dural ectasia, which is a classic manifestation of Marfan's syndrome. Marfan's syndrome is thought to be caused by a genetic mutation in the FBN1 gene (fibrillin-1).

Marfan's syndrome is an autosomal dominant condition caused by a mutation in the FBN1 gene. Orthopaedic manifestations of the condition include dural ectasia, scoliosis, protrusio acetabuli, ligamentous laxity, and pes planovalgus.

Loeys et al. present a revised Ghent nosology for the diagnosis of Marfan's syndrome. Their two main cardinal manifestations include aortic root aneurysm and ectopia lentis. No genetic testing is necessary to confirm the diagnosis if both are present. If one or none are present, the presence of the FBN1 mutation or a combination of systemic manifestations is necessary to make the diagnosis.

Shirley et al. report the musculoskeletal manifestations of Marfan's syndrome include scoliosis, dural ectasia, protrusio acetabuli, and ligamentous laxity. They also describe how the FBN1 gene is located on chromosome 15 and the gene mutation is present in >90% of patients with Marfan's.

Figure B is an axial cut from a T2-weighted MRI showing dural ectasia, or "ballooning" of the dural sac.

Incorrect Answers:
Answer 1: Figure A is a clinical photo showing an elevated scapula characteristic of Sprengel's deformity. Sprengel's deformity is not associated with the FBN1 gene.
Answer 3: Figure C shows a lateral radiograph in a child with sacral agenesis. Sacral agenesis is not associated with the FBN1 gene.
Answer 4: Figure D shows a radiograph of fibular hemimelia. Fibular hemimelia has been linked to the sonic hedge-hog gene.
Answer 5: Figure E is a clinical photo showing Lisch nodules, benign pigmented hamartomas of the iris, both consistent with neurofibromatosis. Neurofibromatosis is linked to the NF1 gene.