GPAtlas🧭 When to suspect
Marfan syndrome is an autosomal dominant disorder of connective tissue caused by pathogenic variants in the fibrillin-1 (FBN1) gene on chromosome 15, with features across the skeletal, ocular and cardiovascular systems. Suspect it in a tall, slim person with disproportionately long limbs (an arm span greater than height, dolichostenomelia) and long, slender fingers (arachnodactyly). A first-degree family history is present in around three-quarters of cases; roughly a quarter arise de novo, so its absence does not exclude the diagnosis.
The clinical priority is the aorta. Progressive dilatation of the aortic root follows a long, silent course before a type A aortic dissection – the leading cause of premature death – which is why structured echocardiographic surveillance and timely prophylactic surgery transform prognosis. The two cardinal diagnostic features of the revised Ghent nosology are aortic root dilatation (a Z-score ≥ 2, meaning at least two standard deviations above the size- and age-adjusted mean) and ectopia lentis (lens dislocation).
Once suspected, confirm the diagnosis and assess relatives through specialist services. Management is then governed largely by the maximum aortic root diameter:
| Aortic root | Action |
|---|---|
| Within normal limits (Z-score < 2) | No aneurysm – treat as at-risk; baseline review and cascade family screening |
| Dilated, < 4.5 cm | Annual echocardiogram; beta-blocker or angiotensin receptor blocker |
| ≥ 4.5 cm, or enlarging > 3 mm/year | 6-monthly echocardiogram; cardiac surgical review |
| ≥ 5.0 cm (or ≥ 4.5 cm with risk factors, or before pregnancy) | Refer for elective aortic root replacement |
Source: Revised Ghent nosology (J Med Genet) · ACC/AHA Aortic Disease Guideline 2022
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