Genetic Testing for Marfan Syndrome

Marfan syndrome is a disease that targets and compromises the connective tissues of the body. Connective tissues hold your body together and provides a foundation for further growth and development. Because connective tissues are found throughout the body--in the skin, the skeletal system, the lungs, the heart and the nervous system--a person with Marfan syndrome can feel the effects throughout his body. The disease is relatively uncommon, affecting only 1 in every 5,000 or 10,000 people regardless of gender or ethnicity. The disease is most commonly inherited.

Causes of Marfan Syndrome

• The cause of Marfan syndrome is a gene mutation defect in the fibrillin-1, or FBN1, gene. This gene synthesizes a protein that is necessary for the manufacture of the elastic fibers found in connective tissue. Such a defect decreases the amounts and the quality of FBN1 that is produced and deposited in the connective tissue. This, in turn, leads to a decrease in structural support of the tissue as a whole. A defective FBN1 gene is usually passed down to offspring, but it can also occur as a result of a gene mutation during the formation of sperm or egg cells.

Statistics

• Marfan syndrome is a relatively rare disease. According to the March of Dimes, approximately 75 percent of people diagnosed with the disease inherited the mutation that causes it from a parent. Only one-fourth of Marfan syndrome cases are the result of a new gene mutation. A parent's odds of passing the disease to any offspring are 50-50; in cases where neither parent has the mutation, only 1 in every 10,000 babies born will have Marfan syndrome.

Symptoms of Marfan Syndrome

• Even though Marfan syndrome is a disease that people are born with, a diagnosis of Marfan syndrome is not commonly made until later in life. While those affected have a defect in the same FBN1 gene, the specific defect varies, and as such, so do the characteristics expressed in those afflicted. The severity of the impact from Marfan syndrome also varies, with some patients having only mild symptoms. The effects of the disease progress with age in all cases.

  Typically, a person with Marfan syndrome will be quite tall and slender, with long appendages and loose joints. One might also see other skeletal abnormalities including a face that is long and disproportionately narrow, scoliosis of the spine and an arched roof of the mouth.

  Eye symptoms may include dislocation of the lenses, retinal detachment, early-onset glaucoma, myopia and cataracts. Most people with Marfan syndrome also experience abnormalities of the heart and circulatory system, including aortic dilatation. With this abnormality, the risk of aortic dissection or rupture is much higher than among people without this condition and can cause serious heart problems or sudden death. Heart murmurs are also common.

  Nervous system problems include a progressive weakening of the dura, the material surrounding the spine. This can cause pain, numbness and weakness in the lower extremities. People with Marfan syndrome may also experience sleep disorders such as snoring or sleep apnea or have skin or abdominal problems such as stretch marks (with no change in weight) or inguinal hernia.

Genetic Testing and Diagnosis

• There is no specific test for Marfan syndrome. A doctor or geneticist may rely on a physical exam, a patient's medical history or simple observation to diagnose the disease. Genetic testing for Marfan syndrome can also be performed. One should not assume that one has Marfan syndrome simply because the disease has existed in previous generations.

  Genetic testing is best used after clinical diagnosis, with the hope of determining the specific defect to the FBN1 gene. This may also help to determine if any other family members have the same condition. Genetic testing is costly and time-consuming and may not provide any more information for patients and their families. For this reason, it is not the primary route of diagnosis for most medical professionals.

Treatment and Prognosis

• Marfan syndrome affects many parts of the body. As such, most of the treatments for this disorder center on treating the individual conditions caused by the disease. A person with Marfan syndrome will likely have several doctors following his case and providing treatment. Care should come from specialists in any one area, with an emphasis placed on mitigating the symptoms of the disease and on preventive care.

  While there is no specific cure for Marfan syndrome, earlier diagnosis provides time to ensure a more positive outcome. The life expectancy of a person with Marfan syndrome is no different than that of a person without the condition. The key to living well with Marfan syndrome is diligence and proactive maintenance.