Histology · Year 1 · from Histology
Case 3: Marfan Syndrome
Clinical Image
Source: Wikipedia - Marfan Syndrome - CC BY-SA 3.0
Case Presentation
A 22-year-old male basketball player collapses during practice and is brought to the emergency department. He is tall (6'7"), thin, with disproportionately long arms (arm span exceeds height) and long, slender fingers (arachnodactyly). The "thumb sign" (Steinberg sign) is positive - his thumb extends past the ulnar border when clasped in his fist. Ophthalmologic examination reveals superior lens dislocation (ectopia lentis). Echocardiography demonstrates significant aortic root dilation (5.2 cm, normal <4 cm) with mild aortic regurgitation. Genetic testing confirms a mutation in FBN1, the gene encoding fibrillin-1. The diagnosis is Marfan syndrome. He is started on beta-blocker therapy to reduce hemodynamic stress on the aorta and referred for cardiovascular surgery consultation. He is counseled to avoid strenuous exercise and contact sports due to risk of aortic dissection - the leading cause of death in Marfan syndrome.
Key Learning Points
- Marfan syndrome results from mutations in fibrillin-1, the microfibrillar component of elastic fibers
- Defective elastic fibers affect tissues requiring stretch and recoil: aorta, lens zonules, and ligaments
- The cardiovascular manifestations (aortic root dilation, dissection, mitral valve prolapse) are the most life-threatening
- Understanding elastic fiber composition explains the multisystem manifestations: skeleton, eyes, and cardiovascular system
Summary: Connective Tissue Disorders
These cases illustrate how defects in different connective tissue components produce distinct clinical syndromes:
| Disorder | Defective Component | Key Clinical Features | Histological Finding |
|---|---|---|---|
| Ehlers-Danlos (Classical) | Type V collagen | Skin hyperextensibility, joint hypermobility, poor wound healing | Disorganized, thin collagen fibers |
| Scurvy | Collagen hydroxylation | Bleeding gums, petechiae, poor wound healing | Defective collagen synthesis and degradation |
| Marfan Syndrome | Fibrillin-1 (elastic fibers) | Tall stature, arachnodactyly, lens dislocation, aortic dilation | Fragmented, disorganized elastic fibers |
Understanding connective tissue structure and synthesis is essential for recognizing and managing these conditions.