Marfan syndrome is inherited as an autosomal dominant trait. However, up to 30% of cases have no family history and are so called "sporadic" cases. In sporadic cases, Marfan syndrome is believed to result from a spontaneous new mutation.

Marfan syndrome is caused by mutations in the gene fibrillin-1. Fibrillin-1 plays an important role as the “scaffolding” for elastic tissue in the body. Disruption of such scaffolding (by mutations in fibrillin-1) thus results in changes in elastic tissues, particularly in the aorta, eye, and skin. Mutations in fibrillin-1 also cause overgrowth of the long bones of the body, resulting in the tall stature and long limbs seen in Marfan patients.

How this overgrowth happens is not well understood. Marfan syndrome causes skeletal defects typically recognized in a tall, lanky person with long limbs and spider-like fingers (arachnodactyly), chest abnormalities (pectus excavatum or pectus carinatum), curvature of the spine, and a particular set of facial features, including a highly arched palate and crowded teeth.

Common eye problems are nearsightedness and dislocation of the lens of the eye.

The most significant of the defects in the syndrome are cardiovascular abnormalities, which may include enlargement (dilatation) of the base of the aorta (aortic root), with aortic regurgitation, and prolapse of the mitral valve. Affected people may develop a dissecting aortic aneurysm.

• Family history of Marfan syndrome
• Long, lanky frame
• Long, thin limbs
• Armspan significantly greater than body height
• Long, spidery fingers (arachnodactyly)
• Funnel chest (pectus excavatum) or pigeon breast (pectus carinatum)
• Scoliosis
• Visual difficulties
• Flat feet
• Learning disability/school problems
• Thin, narrow face
• Micrognathia (small lower jaw)
• Coloboma of iris
• Hypotonia

• Joint laxity (hypermobile joints)
• Myopia
• Dislocation of lens (ectopia lentis)
• Malformed cornea (flat)
• Retinal detachment

• Dilated aortic root
• Aortic regurgitation
• Dissecting aortic aneurysm
• Mitral valve prolapse
• Other aortic aneurysms (thoracic or abdominal)
• Pneumothorax (collapsed lung)

The following tests may be performed:

• Echocardiogram
• Eye examination
• Fibrillin-1 mutation testing (in some individuals)

There is not a single, curative treatment for this condition.

Visual defects should be corrected where possible. Care should be taken to prevent the development of scoliosis, especially during adolescence.

The cardiovascular abnormalities are the most worrisome. The goal is primarily to prevent dilatation of the aortic root. Dilatation can lead to dissection or rupture of the aorta, both serious medical conditions that can be fatal. Medication to slow the heart rate (beta blockers) can help prevent stress on the aorta. Competitive athletics and contact sports should be discouraged as well. An echocardiogram to assess the aortic root should be performed every year. In some cases, surgical replacement of the aortic root and valve is needed.

People with Marfan should have preventive antibiotics before dental procedures in order to prevent endocarditis. Pregnancy in individuals with Marfan needs to be monitored very closely because of the increased stress on the heart and aorta.

• Dissecting aortic aneurysm
• Aortic rupture
• Bacterial endocarditis
• Heart failure