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Marfan Syndrome

What is Marfan syndrome?

The Marfan syndrome is a heritable condition that affects the strength of the connective tissues that hold parts of the body together and provide a framework for growth and development. Because connective tissue is found throughout the body, patients with Marfan syndrome have problems with a number of systems including the skeleton, eyes, heart and blood vessels, nervous system, skin and lungs.

Marfan syndrome affects both sexes and all ethnic groups. However, it is relatively rare. About 1 in 7500 people are born with the disorder and an estimated 200,000 individuals in the United States are currently diagnosed with it.

What causes Marfan syndrome?

Marfan syndrome results from mutations in the FBN1 gene that codes for fibrillin, one of the essential components of connective tissue. Three out of every four people with Marfan syndrome inherit the disorder from a parent with the disease.

How is Marfan syndrome inherited?

This autosomal dominant condition appears in successive generations, with each new child of an affected parent having a fifty percent chance of inheriting the disease. Spontaneous mutations in FBN1 account for the remaining twenty-five percent of cases. The likelihood of such a mutation is quite uncommon, occurring in about 1 of 20,000 births.

What are the clinical features of Marfan syndrome and how is it diagnosed?

The diagnosis of Marfan syndrome remains a clinical one. There is a wide range of variability in the manifestations of the disease within and among families. Also, many individuals without the syndrome have one or more clinical features that may suggest that they may have Marfan syndrome and can be the reason for referral for work-up for the Marfan syndrome. Such common features include tall and thin stature, heart murmurs or eye problems. Only when patients have a sufficient number of the clinical manifestations of Marfan syndrome can a firm clinical diagnosis be made.

Is there a genetic test for Marfan syndrome?

Ideally, molecular genetic testing for mutations in FBN1 will confirm a clinical diagnosis, but this test is not widely available at this time. Furthermore, in some patients the clinical features are so characteristic that FBN1 testing will not add to the certitude of the diagnosis.

Fig. 1 Subluxated lens (ectopia lentis).

What are the ocular features of Marfan syndrome?

Most people with Marfan syndrome suffer from near-sightedness (axial and lenticular myopia) and visual distortion (astigmatism). Other signs and symptoms among include ectopia lentis, thinning of the cornea, flattened corneal curvature, early onset cataracts, glaucoma, strabismus, and retinal detachment.

What is ectopia lentis?

Ectopia lentis is the subluxation or dislocation of the crystalline lens, where the zonules holding the lens weaken and the lens moves off center. This occurs in roughly sixty-percent of individuals with Marfan syndrome and is one of the major criteria for the clinical diagnosis of this condition [See figures 1 and 2]. Absence of dislocated lenses does not rule out Marfan syndrome.

How does Marfan syndrome affect the heart and blood vessels?

Many of the symptoms of Marfan syndrome are striking, but the most serious problems associated with the Marfan syndrome involve the cardiovascular system. The mitral valve leaflets are usually too large and pliant for the openings they need to cover, and can induce an abnormal, backward billowing motion (mitral valve prolapse). In numerous individuals with MVP, the mitral valve makes a click as it moves backward, a sound that can be detected with a stethoscope. In about one-third of people with prolapse blood leaks backward through the valve (mitral valve regurgitation) producing a heart murmur that can also be heard through a stethoscope. A few individuals with mitral regurgitation develop symptoms like breathlessness, an irregular pulse (palpitations), or extreme tiredness. An enlargement of the aortic root occurs to some degree in nearly everyone with Marfan syndrome. A substantial (about two inches) dilatation of the aorta (aneurysm) can result in two things: an abnormal back-flow of blood into the heart (aortic regurgitation) or a tear in the middle layer of the aorta (dissection). Dissecting aortic aneurysms are the most frequent cause of death in persons with Marfan syndrome.

Fig. 2 Same lens as Fig. 1 with retroillumination.

How does Marfan syndrome affect the skeletal system?

Most patients are evaluated for Marfan syndrome because of their skeletal manifestations. A person with the disorder will usually be tall, thin, and loose-jointed. Frequent symptoms of the disease include long, slender fingers and toes (arachnodactyly) and flat arches (pes planus). Curvature of the spine (scoliosis and kyphosis) and protrusion or indentations of the breastbone (pectus carinatum and excavatum) are also common manifestations. The roof of the mouth (palate) may be highly arched, causing dental crowding, and the face may seem narrow and elongated. Persons with Marfan syndrome may also demonstrate an arm-span-to-height ratio greater than 1.05.

How does Marfan syndrome affect the skin?

Striae are bands of thin wrinkled skin, initially red but becoming purple and white, which tend to appear in areas prone to stress, such as the shoulders, hips, and lower back.

How does Marfan syndrome affect the lungs?

Decreased flexibility in the air sacs of the lungs can be detected in nearly everybody with the disease, but does not pose any serious problem. One out of twenty people diagnosed with the condition experience the feeling of breathlessness or chest pain as a direct result of the spontaneous collapse of the lung (spontaneous pneumothorax). Some people with Marfan syndrome also suffer from sleep-disordered breathing.

How does Marfan syndrome affect the dura?

In people with Marfan syndrome, the dura, a fluid filled membrane surrounding the central nervous system, may enlarge (dural ectasia) and push on the bones of the vertebral column, therefore widening the spinal canal and eroding the bone surrounding it. Mild degrees of dural ectasia, however, are generally without symptoms. The dural ectasia may also expand and push through natural gaps in the backbone into the abdomen.

Is Marfan syndrome curable?

There is no cure for Marfan syndrome yet, but accurate medical management can improve the prognosis.

What is the prognosis for persons with Marfan syndrome?

Individuals with Marfan syndrome can manifest severe orthopedic, cardiovascular, and ocular challenges, but medical and surgical advancements have increased the life span of people with Marfan syndrome dramatically over the last two decades. In 1972 the average life expectancy was about forty-five years, now the average life expectancy is about seventy years.

How should Marfan syndrome patients be monitored?

• Annual echocardiogram to monitor the heart
• Initial careful slit-lamp eye examination, with regular follow-up
• Careful monitoring of the skeletal system
• Lifestyle adjustments: avoidance of strenuous activity and contact sports

What cardiovascular treatments are used for Marfan syndrome patients?

The use of beta-blocker agents, medications used to prevent progressive enlargement of the aorta and treat high blood pressure, have become an essential aspect of cardiovascular management. Individuals with Marfan syndrome are advised to refrain from heavy lifting and forceful activity. In the case of aortic regurgitation or significant dilation of the aortic root, surgical repair may become necessary.

What skeletal treatments are used for Marfan syndrome patients?

A back brace is often recommended for children with scoliosis between 20º and 40º. If the curve becomes more than 40º, surgery is usually considered to prevent further complications. Treatments for severe cases of dural ectasia include spinal shunting and medication, but it is best to leave mild cases alone. The sole treatment for pectus excavatum or carinatum is surgery. Management for pes planus is not ordinarily required, but special cushions, inserts, or orthotics may help. Wearing comfortable shoes is also recommended.

What ocular treatments are used for Marfan syndrome patients?

Comprehensive ophthalmologic care is necessary to achieve the best possible vision in people with Marfan syndrome. Patients with subluxated lenses are treated with glasses or contact lenses whenever possible; surgery may be necessary, but there is a risk of retinal detachment. Individuals with cataracts require lens extraction with or without placement of an intraocular lens. Glaucoma may require treatment with medications or surgery.

When should the dislocated lens be removed in Marfan syndrome patients?

Removal of clear, dislocated lenses in children remains a difficult decision to make. There is a general consensus that they should be removed if they are interfering significantly with vision by causing large degrees of astigmatism that cannot be corrected with glasses or contact lenses. Lens extraction in children with Marfan syndrome does have an increased risk of complications.

Where can I find more information about Marfan syndrome?

Please visit the National Marfan Foundation website. A large number of frequently asked questions have been answered by experts in the field under the heading of “living with Marfan syndrome”.
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