Marfan and Ehlers-Danlos Syndromes
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Direct answer
Marfan and Ehlers-Danlos syndromes are heritable connective tissue disorders with overlapping joint hypermobility, scoliosis and protrusio acetabuli, caused by defects in fibrillin-1 or collagen. Marfan syndrome is recognised by the Steinberg and Walker-Murdoch signs and by aortic root dilatation, a major cause of death. Ehlers-Danlos syndromes are heterogeneous, and the vascular type is the most dangerous because of arterial rupture.
What you must remember
- Marfan genetics: autosomal dominant, caused by FBN1 mutations affecting fibrillin-1, with many cases arising from new mutations.
- Steinberg sign: the thumb projects beyond the ulnar border of the closed fist. Walker-Murdoch sign: the thumb and little finger overlap when the wrist is encircled.
- Skeletal features: arachnodactyly, arm span exceeding height, pectus excavatum or carinatum, high-arched palate and scoliosis.
- Cardiac and ocular features: aortic root dilatation that can dissect, mitral valve prolapse, and ectopia lentis, usually displaced upwards and outwards.
- Ehlers-Danlos: a heterogeneous group of collagen disorders defined by skin hyperextensibility, atrophic scarring and joint hypermobility, with the classical, hypermobile and vascular types the main ones.
- Vascular EDS: COL3A1 defects cause arterial, uterine or bowel rupture, making this the most dangerous type.
- Protrusio acetabuli: medial migration of the femoral head through a thinned acetabular floor, classically in Marfan syndrome and reported in Ehlers-Danlos, causing hip pain, early arthritis and deficient bone stock.
A tall man with a long reach and a curved spine
A 22-year-old tall man has an arm span longer than his height, recurrent shoulder subluxation and a curved spine noticed at a college health check. Hypermobility and the family history will help decide between the two syndromes.
- Measure the habitus. Arm span exceeding height, arachnodactyly and a high-arched palate flag a systemic connective tissue disorder that needs wider review.
- Apply the bedside signs. The Steinberg and Walker-Murdoch signs, together with a Beighton score out of nine, document skeletal length and generalised hypermobility.
- Examine the spine and chest. Scoliosis, pectus deformity and protrusio acetabuli are documented clinically and on radiographs, with the curve measured by its Cobb angle.
- Screen the heart and eyes. Echocardiography for aortic root size and mitral valve prolapse, and ophthalmic review for ectopia lentis, are arranged in suspected Marfan syndrome.
- Assess skin and vessels. Atrophic scarring, easy bruising and a family history of arterial events prompt genetic testing for vascular Ehlers-Danlos syndrome before any elective procedure.
- Counsel and monitor. Genetic counselling for autosomal dominant inheritance, beta-blockers to slow aortic root growth, and avoidance of fluoroquinolones form the core plan.
Connective tissue traps in the examination
Most traps come from treating hypermobility as harmless.
- Trap: attributing tall stature and dislocations to simple hypermobility without checking the aorta Correct: Marfan and vascular Ehlers-Danlos carry aortic or arterial risk, so echocardiography and cardiology review are part of the assessment.
- Trap: prescribing a fluoroquinolone for an infection in Marfan syndrome Correct: these antibiotics are linked with aortic aneurysm and dissection, so an alternative agent is chosen.
- Trap: treating the Steinberg and Walker-Murdoch signs as proof of Ehlers-Danlos Correct: they are bedside signs of arachnodactyly seen in Marfan syndrome, and diagnosis rests on criteria and genetics.
Frequently asked questions
What is the Walker-Murdoch wrist sign?
The Walker-Murdoch wrist sign is positive when the thumb and little finger overlap after the patient encircles the opposite wrist with them. It is a bedside sign of arachnodactyly seen in Marfan syndrome, and it complements the Steinberg thumb sign in the examination.
Which cardiovascular complication is most dangerous in Marfan syndrome?
Aortic root dilatation that can progress to dissection is the most dangerous cardiovascular complication in Marfan syndrome. Beta-blockers are used to slow aortic growth, and planned root surgery is considered when the aorta reaches a critical size.
Which type of Ehlers-Danlos syndrome carries the highest risk of arterial rupture?
Vascular Ehlers-Danlos syndrome, caused by COL3A1 defects, carries the highest risk of arterial, uterine or bowel rupture. Its features include thin translucent skin, easy bruising and a characteristic facial appearance, so it is a critical diagnosis to recognise.
What is protrusio acetabuli and why does it matter?
Protrusio acetabuli is medial migration of the femoral head through a thinned acetabular floor into the pelvis, classically in Marfan syndrome and also reported in Ehlers-Danlos syndromes. It causes hip pain and early arthritis, and it complicates total hip arthroplasty because the acetabular bone stock may be deficient.
Why are fluoroquinolones avoided in Marfan syndrome?
Fluoroquinolones are linked with aortic aneurysm and dissection, particularly in patients with connective tissue disorders such as Marfan syndrome. Alternative antibiotics are therefore preferred whenever a suitable option exists.