Distinguishing Ehlers-Danlos Syndrome from Marfan Syndrome on Exam
The key distinguishing features are: Marfan syndrome presents with ectopia lentis and significant aortic root dilation (>40-42 mm) with risk of dissection, while Ehlers-Danlos syndrome presents with soft/velvety hyperextensible skin, more severe joint hypermobility (Beighton score ≥5), and only mild aortic dilation without dissection risk unless significantly dilated. 1
Primary Distinguishing Features
Ocular Findings
- Ectopia lentis is pathognomonic for Marfan syndrome and essentially rules out EDS 1, 2
- A dilated ophthalmologic examination is mandatory to differentiate these conditions 1, 2
- EDS does not cause lens dislocation 1
Cardiovascular Differences
- Marfan syndrome: Significant aortic root dilation (>40-42 mm even in tall individuals) with high risk of dissection requiring surgical intervention at ≥4.5-5.0 cm 1, 2
- EDS hypermobile type: Only mild aortic root dilation occurs in one-quarter to one-third of patients, with no dissection risk without significant dilation 1
- This cardiovascular risk profile difference is critical for morbidity and mortality 1
Skin Characteristics
- EDS: Soft, velvety skin texture with mild to moderate hyperextensibility is a major diagnostic criterion 1
- Marfan syndrome: Skin is rarely hyperextensible 1
- This is one of the most reliable bedside distinguishing features 1
Joint Hypermobility Assessment
Beighton Scale Application
Both conditions can present with joint hypermobility, but the pattern differs 1, 2:
- EDS requires Beighton score ≥5/9 as a major diagnostic criterion 1
- Marfan syndrome: Joint hypermobility contributes to systemic score (wrist AND thumb sign = 3 points; wrist OR thumb sign = 1 point) but is not the dominant feature 1
- EDS typically shows more severe and generalized joint laxity with recurrent dislocations/subluxations 1
Skeletal and Body Habitus
Marfan-Specific Features
- Arm span-to-height ratio >1.05 and increased lower extremity-to-body ratio are characteristic 1
- Pectus deformities score in the systemic features (carinatum = 2 points, excavatum = 1 point) 1
- Tall stature with disproportionately long limbs 1
EDS Features
- Short stature occurs in 44% of EDS patients 3
- High, narrow palate and dental crowding are minor criteria 1
- No characteristic body proportion abnormalities 1
Additional Distinguishing Clinical Features
EDS-Specific Findings
- Easy bruising is a characteristic minor criterion 1
- Functional bowel disorders (gastritis, irritable bowel syndrome) 1
- Chronic joint and limb pain 1
- Neurally mediated hypotension or postural orthostatic tachycardia 1
- Osteoporosis is common (present in all patients in one series) 3
Marfan-Specific Findings
- Dural ectasia (scores 2 points in systemic features) 1
- Pneumothorax (scores 2 points) 1
- Protrusio acetabuli (scores 2 points) 1
- These features are not associated with EDS 1
Genetic and Diagnostic Workup
Marfan Syndrome Diagnosis
- Requires either: (1) aortic root dilation AND ectopia lentis, (2) aortic root dilation AND FBN1 mutation, or (3) aortic root dilation AND systemic score ≥7 points 1
- FBN1 mutations identified in 90% of cases 4
EDS Hypermobile Type Diagnosis
- All three major criteria must be met: Beighton score ≥5, soft/velvety skin with normal or slightly increased extensibility, and absence of skin/soft tissue fragility 1
- Only a small subset have TNXB gene mutations 1
- Genetic testing can rule out Marfan syndrome when clinical overlap exists 5
Critical Pitfall to Avoid
The most dangerous error is misdiagnosing Marfan syndrome as EDS, because this leads to inadequate cardiovascular surveillance and missed opportunities for life-saving prophylactic aortic surgery 1, 4. Marfan syndrome without treatment has a median survival of 40 years due to aortic dissection/rupture, while proper management extends life expectancy to 60-70 years 4. Always perform echocardiography and dilated eye examination in any patient with joint hypermobility to exclude Marfan syndrome 1, 2.