Marfan syndrome

Synonyms

4

Overview

Marfan syndrome is a genetic disorder of connective tissue. Connective tissue provides strength and flexibility to structures throughout the body such as bones, ligaments, muscles, walls of blood vessels, and heart valves. It has a variable clinical presentation, ranging from mild to severe systemic disease. The most serious manifestations involve defects of the heart valves and aorta, which may lead to early death if not properly managed. The syndrome also may affect the lungs, eyes, dural sac surrounding the spinal cord, the skeleton, and the hard palate. The signs and symptoms of Marfan syndrome vary widely in severity, timing of onset, and rate of progression.

The two primary features of Marfan syndrome are vision problems caused by a dislocated lens (ectopia lentis) in one or both eyes and defects in the large blood vessel that distributes blood from the heart to the rest of the body (the aorta). The aorta can weaken and stretch, which may lead to a bulge in the blood vessel wall (an aneurysm). Stretching of the aorta may cause the aortic valve to leak, which can lead to a sudden tearing of the layers in the aorta wall (aortic dissection). Aortic aneurysm and dissection can be life threatening.

Many people with Marfan syndrome have additional heart problems including a leak in the valve that connects two of the four chambers of the heart (mitral valve prolapse) or the valve that regulates blood flow from the heart into the aorta (aortic valve regurgitation). Leaks in these valves can cause shortness of breath, fatigue, and an irregular heartbeat felt as skipped or extra beats (palpitations). The damage caused by Marfan syndrome can be mild or severe.

People with Marfan syndrome tend to be unusually tall, with long limbs and long, thin fingers and toes (arachnodactyly), and have an arm span that exceeds their body height. Other common features include a long and narrow face, crowded teeth, an abnormal curvature of the spine (scoliosis orkyphosis), and either a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum). Some individuals develop an abnormal accumulation of air in the chest cavity that can result in the collapse of a lung (spontaneous pneumothorax). A membrane called the dura, which surrounds the brain and spinal cord, can be abnormally enlarged (dural ectasia) in people with Marfan syndrome. Dural ectasia can cause pain in the back, abdomen, legs, or head. Most individuals with Marfan syndrome have some degree of nearsightedness (myopia). Clouding of the lens (cataract) may occur in mid-adulthood, and increased pressure within the eye (glaucoma) occurs more frequently in people with Marfan syndrome than in those without the condition.

The features of Marfan syndrome can become apparent anytime between infancy and adulthood. Depending on the onset and severity of signs and symptoms, Marfan can be fatal early in life; however, the majority of affected individuals survive into mid- to late adulthood.

Named after Antoine Marfan, the French pediatrician who first described the condition in 1896, the disease is an autosomal dominantdisorder. Management often includes the use of angiotensin II receptor antagonists (ARBs) and beta blockers.

Symptoms

The signs and symptoms of Marfan syndrome vary widely in severity, timing of onset, and rate of progression. Affected individuals often are tall and lean, have elongated fingers and toes (arachnodactyly), and have an arm span that exceeds body height. Other common features include unusually flexible joints, a long and narrow face, a highly arched roof of the mouth and crowded teeth, an abnormal curvature of the spine (scoliosis), and either a sunken chest (pectus excavatum) or a protruding chest (pectus carinatum). About half of people with Marfan syndrome have a dislocated lens (ectopia lentis) in one or both eyes, and most have some degree of nearsightedness (myopia). Clouding of the lens (cataract) may occur in mid adulthood, and increased pressure within the eye (glaucoma) occurs more frequently than in people without Marfan syndrome.

Most people with Marfan syndrome have abnormalities of the heart and the aorta. Leaks in valves that control blood flow through the heart can cause shortness of breath, fatigue, and an irregular heartbeat felt as skipped or extra beats (palpitations). If leakage occurs, it usually affects the mitral valve, which is a valve between two chambers of the heart, or the aortic valve that regulates blood flow from the heart into the aorta. The first few inches of the aorta can weaken and stretch, which may lead to a bulge in the blood vessel wall (an aneurysm). The increased size of the aorta may cause the aortic valve to leak, which can lead to a sudden tearing of the layers in the aorta wall (aortic dissection). Aortic aneurysm and dissection can be life threatening. 

Causes

Marfan syndrome is caused by a defect in the gene that enables your body to produce a protein that helps give connective tissue its elasticity and strength. Marfan syndrome is caused by defects in a gene called fibrillin-1. Fibrillin-1 plays an important role as the building blocks for elastic tissue in the body. A problem with this gene results in changes in elastic tissues, particularly in the aorta, eye, and skin. The gene defect also causes overgrowth of the long bones of the body. resulting in the tall height and long arms and legs seen in persons with this syndrome. How this overgrowth happens is not well understood. In most cases, Marfan syndrome is inherited, which means it is passed down through families. However, up to 30% of cases have no family history. Such cases are called "sporadic" In sporadic cases, the syndrome is believed to result from a spontaneous new gene defect.

Most people with Marfan syndrome inherit the abnormal gene from a parent who has the disorder. Each child of an affected parent has a 50-50 chance of inheriting the defective gene. In about 25 percent of the people who have Marfan syndrome, the abnormal gene doesn't come from either parent. In these cases, a new mutation develops spontaneously.

Prevention

Spontaneous new mutations leading to Marfan (less than 1/3 of cases) cannot be prevented.

Diagnosis

Marfan syndrome can be challenging for doctors to diagnose because many connective tissue disorders have similar signs and symptoms. Even among members of the same family, the signs and symptoms of Marfan syndrome vary widely — both in their features and in their severity.

Certain combinations of symptoms and family history must be present to confirm a diagnosis of Marfan syndrome. In some cases, a person may have some features of Marfan syndrome, but not enough of them to be diagnosed with the disorder.

Heart tests:

If your doctor suspects Marfan syndrome, one of the first tests he or she may recommend is an echocardiogram. This test uses sound waves to capture real-time images of your heart in motion. It checks the condition of your heart valves and the size of your aorta. Other heart-imaging options include computerized tomography (CT) scans and magnetic resonance imaging (MRI).

If you are diagnosed with Marfan syndrome, you'll need to have regular echocardiograms to monitor the size and condition of your aorta.

Eye tests:

Eye exams that may be needed include:

Slit-lamp exam. This test checks for lens dislocation, cataracts or a detached retina. Your eyes will need to be completely dilated with drops for this exam.
Eye pressure test. To check for glaucoma, your eye doctor may measure the pressure inside your eyeball by touching it with a special tool. Numbing eyedrops are usually used before this test.
Genetic testing:

If findings from standard exams for Marfan syndrome aren't clear-cut, genetic testing can be helpful. You may also want to talk to a genetic counselor before starting a family, to see what your chances are of passing on Marfan syndrome to your future children.

 

Prognosis

Heart-related complications may shorten the lifespan of persons with this disease. However, many patients survive well into their 60s. The lifespan may be extended further with good care and heart surgery.

Treatment

While there is no cure for Marfan syndrome, treatment focuses on preventing the various complications of the disease. To accomplish this, you'll need to be checked regularly for signs that the damage caused by the disease is progressing.

In the past, people who had Marfan syndrome rarely lived past 40. With regular monitoring and modern treatment, most people with Marfan syndrome can now expect to live a more normal life span.

Medications:

Doctors often prescribe blood pressure lowering drugs to help prevent the aorta from enlarging and to reduce the risk of dissection and rupture. The most commonly used drugs are beta blockers, which cause your heart to beat more slowly and with less force. Losartan (Cozaar), a newer blood pressure medication, also is useful for protecting the aorta.

Therapy:

A dislocated lens in your eye can be treated effectively with glasses or contact lenses that refract around or through the lens.

Surgical and other procedures:

Depending upon your signs and symptoms, procedures might include:

  • Aortic repair. If your aorta's diameter enlarges quickly or reaches about 2 inches (5 centimeters), your doctor may recommend an operation to replace a portion of your aorta with a tube made of synthetic material. This can help prevent a life-threatening rupture. Your aortic valve may need to be replaced as well.
  • Scoliosis treatment. For some children and adolescents, doctors recommend a custom-made back brace, which is worn nearly continuously until growth is complete. If the curve in your child's spine is too great, your doctor may suggest surgery to straighten the spine.
  • Breastbone corrections. Surgical options are available to correct the appearance of a sunken or protruding breastbone. Because these operations are often considered to be for cosmetic purposes, your insurance might not cover the costs.
  • Eye surgeries. If parts of your retina have torn or come loose from the back of your eye, surgical repair is usually successful. If you have cataracts, your clouded lens can be replaced with an artificial lens.


Resources

  • NIH
  • Mayo Clinic
  • Genetics Home Reference