Marfan Syndrome

What Marfan syndrome is

Marfan syndrome is an inherited connective tissue disorder, usually caused by a change in the FBN1 gene, which makes a protein (fibrillin-1) that helps give connective tissue its strength and elasticity. It affects several systems — the skeleton, the eyes, and, most importantly, the heart and the aorta (the body’s main artery). It occurs in roughly one in five thousand people.

The reason Marfan syndrome is taken seriously is cardiovascular, not cosmetic: the aorta can gradually widen at its root and, if unrecognized, tear or rupture. The great majority of that risk is preventable with timely diagnosis and regular monitoring — which is exactly why recognizing the pattern and confirming the diagnosis matters so much.

How Marfan syndrome is actually diagnosed — the revised Ghent criteria

Like hEDS, Marfan syndrome is not diagnosed by a glance at someone who is tall with long fingers. It is diagnosed with a defined framework, the revised Ghent nosology (2010), which is built around two cardinal features: dilation of the aortic root (measured as a Z-score, which adjusts for age and body size) and ectopia lentis (a dislocated lens of the eye).

In a person without a family history, any one of these combinations establishes the diagnosis: aortic root dilation (Z-score of 2 or more) plus ectopia lentis; or aortic root dilation plus a disease-causing FBN1 gene change; or aortic root dilation plus a systemic score of 7 or more; or ectopia lentis plus an FBN1 change already known to cause aortic disease.

When a close relative already has a confirmed diagnosis, fewer features are needed: ectopia lentis, or a systemic score of 7 or more, or aortic root dilation (Z-score of 2 or more in adults, or 3 or more under age 20).

The systemic score is a point checklist of connective tissue findings — many of them orthopaedic — including the wrist and thumb signs, chest deformity, flat feet or hindfoot deformity, scoliosis, reduced elbow extension, an increased arm-span-to-height ratio, certain facial features, skin stretch marks, nearsightedness, mitral valve prolapse, and dural ectasia. A score of 7 or more counts toward the diagnosis. Conditions that can look similar — Loeys-Dietz syndrome, vascular EDS, and the MASS phenotype — must be considered and excluded, sometimes with genetic testing.

Orthopaedic manifestations

The skeleton often shows the first visible clues, which is why an orthopaedic surgeon is sometimes the one to recognize the pattern. Common features include:

• Tall stature with long limbs, and long slender fingers (the wrist sign and thumb sign are quick bedside checks)
• Scoliosis or other spinal curvature
• Chest-wall deformity — a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum)
• Flat feet and hindfoot deformity, and joint hypermobility
• Reduced elbow extension, a high-arched palate with dental crowding, and — deep around the spine — dural ectasia

Several of these contribute to the systemic score, so the orthopaedic exam is part of the diagnostic picture. Orthopaedic care addresses scoliosis and chest-wall issues and guides activity, while cardiology leads the aortic monitoring and clears participation in sports.

Common misconceptions

• “Being tall and thin with long fingers means Marfan.” — Those are clues, not a diagnosis. The framework hinges on the aorta and the lens, supported by the systemic score and, where needed, gene testing.
• “Marfan is mainly about height and the skeleton.” — The skeleton is the visible part, but the life-threatening part is the aorta. That is why a suspected diagnosis is taken seriously and referred for heart evaluation.
• “One normal heart scan means I am in the clear.” — The aorta needs ongoing surveillance over time; a single normal echocardiogram does not retire the need for monitoring.
• “A negative gene test rules it out.” — Not by itself. The clinical criteria can still establish the diagnosis, and not every case shows a detectable FBN1 change.

How we help and what to expect

When the skeletal pattern raises the possibility of Marfan syndrome, the most important step an orthopaedic surgeon takes is to ensure the heart and eyes are evaluated — an echocardiogram for the aorta and an eye exam for the lens — and to coordinate with the right specialists. Orthopaedic care then manages scoliosis, chest-wall deformity, and foot or joint problems, while activity recommendations are set together with cardiology, since aortic safety guides which sports and which kinds of straining are advisable.

Learn more

The Marfan Foundation: marfan.org

The Marfan Foundation — Revised Ghent diagnostic rules: marfan.org

This information is for educational purposes only and does not replace evaluation by a qualified clinician. A formal diagnosis of these conditions means that established, published criteria have been met — not simply that someone has been told they have the condition — and the workup often involves genetics, cardiology, or infectious-disease and rheumatology specialists alongside orthopaedic care.