Marfan Syndrome

Introduction

Epidemiology and Aeitiology

• 25% of cases occur without family history
• Reduced life expectancy – average is around 60

Pathology

• The result of a mutation in the fibrillin-1 gene (FBN-1) which results in defective fibrilin. This as a result causes decreased production of extracellular microfibril in connective tissue. Microfibril is involved in the maintenance of elastic fibres, and as a result, there is an alteration in the properties of elastic fibres.
• Microfibrils are associated with  the control TGF-beta activity. Therefore less/defective microfibirils leads to an increase in TGF-Beta activity. This contributes to the destruction of connective tissue. 

Signs and Symptoms

Major signs – diagnostic is >2 present

•  Long limbs, tall, long, spindly fingers (arachnodactyly)
  • The thumb sign – the distal phalanx of the thumb extends beyond the edge of the clenched fist
• Arm length height
• Upwards lens dislocation in the eye (aka ectopia lentis) – the margin of the dislocation lens may been seen through an undilated pupil
• Pectus deformity (e.g. excavatum or carinatum [outwards])
• Aortic dissection / dilatiation – particularly at the aortic root. The arotic media is less resistant to stretching, particularly in areas of high pressure – hence the involvement of the aortic root. In severe cases, dissection can occur before the age of 10! Aortic regurg and endocarditis are also common
• Dural ectasia – widening of the neural canal

Minor signs – may support diagnosis

• Mitral valve prolapse – and accompanying late systolic murmur at the apex
• High arched palate – can cause altered / unusual voice in some patients
• Joint Hypermobility
• Genu recuvatum – hyperextension of the knee, thus is appears to curve backwards
• Scoliosis
• Reduced subcutaneous fat

Diagnosis

• Usually clinical. CT scan may be useful to detect dural ectasia

Treatment

The disease is incurable. 
 Treatment aims to minimise the risk of aortic dissection by preventing excessive dilation of the aortic root. This is usually managed with:

• Β- blockers – e.g. atenolol, propanolol – these reduce the contractility of the heart, and thus reduce the pressure in the aortic root, reducing the risk of dilation and dissection
• Annual Echocardiogram – dilation of >5cm is repaired surgically
• Risk in pregnancy – pregnant women are at particularly high risk of cardiac complications.

Homocystinuria

- See more at: http://almostadoctor.co.uk/content/systems/orthopaedics-and-rheumatology/marfan-syndrome#sthash.EGMDzMiI.dpuf