Distinguishing Ehlers-Danlos Syndrome from Marfan Syndrome

Primary Distinguishing Features

The American College of Medical Genetics and Genomics recommends that ectopia lentis is pathognomonic for Marfan syndrome and essentially rules out Ehlers-Danlos syndrome (EDS) 1, 2
A dilated ophthalmologic examination is mandatory to differentiate Marfan syndrome from EDS, with significant aortic root dilation (>40-42 mm) and high risk of dissection in Marfan syndrome 3, 2
EDS does not cause lens dislocation, and Marfan syndrome typically presents with significant aortic root dilation and ectopia lentis 1, 3

The American Heart Association notes that Marfan syndrome is associated with significant aortic root dilation (>40-42 mm) and high risk of dissection, requiring surgical intervention at ≥4.5-5.0 cm 1, 2
EDS hypermobile type is associated with only mild aortic root dilation, occurring in one-quarter to one-third of patients, with no dissection risk without significant dilation 1, 4, 3

The National Institute of Arthritis and Musculoskeletal and Skin Diseases states that EDS is characterized by soft, velvety skin texture with mild to moderate hyperextensibility, a major diagnostic criterion 1, 4, 3
Marfan syndrome skin is rarely hyperextensible, and this is one of the most reliable bedside distinguishing features 1, 3

The American Academy of Orthopaedic Surgeons recommends that EDS requires a Beighton score ≥5/9 as a major diagnostic criterion, with more severe and generalized joint laxity and recurrent dislocations/subluxations 1, 4, 3
Marfan syndrome joint hypermobility contributes to systemic score, but is not the dominant feature, with wrist and thumb sign scoring 1-3 points 1

The American College of Medical Genetics and Genomics notes that Marfan syndrome is characterized by arm span-to-height ratio >1.05, increased lower extremity-to-body ratio, and tall stature with disproportionately long limbs 1
EDS features include high, narrow palate and dental crowding as minor criteria, with no characteristic body proportion abnormalities 4, 3, 1

The National Institute of Neurological Disorders and Stroke states that EDS-specific findings include easy bruising, functional bowel disorders, chronic joint and limb pain, and neurally mediated hypotension or postural orthostatic tachycardia 4, 3
Marfan syndrome-specific findings include dural ectasia, pneumothorax, and protrusio acetabuli, which are not associated with EDS 1

The American College of Medical Genetics and Genomics recommends that Marfan syndrome diagnosis requires either aortic root dilation and ectopia lentis, aortic root dilation and FBN1 mutation, or aortic root dilation and systemic score ≥7 points 1
EDS hypermobile type diagnosis requires all three major criteria: Beighton score ≥5, soft/velvety skin with normal or slightly increased extensibility, and absence of skin/soft tissue fragility 1, 4, 3