AKT · Child health/Genetic syndromes

Marfan syndrome

FBN1 (fibrillin-1) — autosomal dominant

Overview

An autosomal dominant connective tissue disorder (FBN1/fibrillin-1) affecting the skeleton, eyes and cardiovascular system — the last carrying the lethal risk of aortic root dilatation and dissection.

Recognise

Tall, long limbs (arm span > height), arachnodactyly, joint hypermobility, pectus, high-arched palate, scoliosis
Eyes: upward LENS dislocation (ectopia lentis), myopia
Cardiovascular: aortic root dilatation, aortic dissection, mitral valve prolapse

Red flags

Aortic root dilatation/dissection — the cause of premature death; acute chest/back pain

Differentials & how to tell them apart

Homocystinurialens dislocates DOWNWARD, learning disability, THROMBOSIS, autosomal recessive — opposite lens direction

Ehlers-Danlosskin hyperextensibility/bruising, joint dislocations, less aortic-root focus

Klinefelter47,XXY, hypogonadism

Loeys-Dietzarterial tortuosity, hypertelorism

Investigations

Clinical (Ghent criteria) + FBN1 genetics. Echocardiogram (aortic root) at diagnosis and serially; slit-lamp (lens); MRI/CT aorta.

Management

1Beta-blocker or angiotensin receptor blocker to reduce aortic root dilatation; activity advice (avoid contact/isometric sport).
2Serial echocardiography; prophylactic aortic root replacement at threshold; endocarditis awareness.

Beta-blocker / ARB — slow aortic root dilatation

Prophylactic aortic root surgery — at threshold diameter

Key points

Lens direction is the classic discriminator: Marfan dislocates UP, homocystinuria dislocates DOWN (and adds thrombosis + learning disability).

Monitor & prognosis

Aortic root diameter (serial echo), lens/vision, scoliosis.

Near-normal with cardiovascular surveillance and surgery.

Source: Ghent criteria; clinical genetics