Marfan Syndrome in Sport

Marfan syndrome is an inherited connective tissue disorder that weakens tissues throughout the body, including the wall of the aorta.

It matters in sport for 2 reasons:

• •Its most serious complication, aortic dissection, can be driven by the rise in blood pressure and aortic wall stress with high-intensity exertion, heavy resistance work or breath-holding strain.
• •Affected people are often tall, long-limbed athletes who present first to a sport and exercise medicine (SEM) or musculoskeletal (MSK) clinician with joint, back or chest wall complaints.

The clinician's role is to recognise the phenotype, refer for diagnosis and aortic assessment, and advise on safe activity.

Marfan syndrome is usually caused by a change in the fibrillin-1 gene (FBN1), a protein in the elastic scaffolding of connective tissue. It is autosomal dominant, so an affected parent has a 1 in 2 chance of passing it on, though around a quarter of cases arise from a new mutation with no family history.

Fibrillin-1 sits in many tissues, so the heart and aorta, eyes, skeleton, dura and lungs are affected. Abnormal fibrillin also disturbs transforming growth factor beta (TGF-beta) signalling.

The change that matters most for sport is in the aorta. The wall of the aortic root gradually weakens and widens at the sinuses, just above the heart.

A widened, weakened root is prone to a tear within the wall (aortic dissection) and, in severe cases, full-thickness rupture. Either is an emergency. The aortic and mitral valves may also leak.