Alan C. Braverman, MD
Alan C. Braverman, MD, Alumni Endowed Professor of Cardiovascular Diseases, director, Marfan Syndrome Clinic and Inpatient Cardiology Firm, Washington University School of Medicine, St. Louis. Marfan.org
Bottom Line: Having Marfan syndrome is not always obvious based on appearance.
My cousin just learned that he has Marfan syndrome. Since he’s not excessively tall, that came as a shock to the rest of the family. Should we all be tested?
Marfan syndrome is a genetic connective tissue disorder that comprises a collection of symptoms, the most well-known being tall for one’s family. However, not everyone with Marfan syndrome is extremely tall. Marfan affects men and women equally. Since much of the body, including organs, is made of connective tissue, Marfan has the potential to cause problems with many different body parts. Doctors look for features involving multiple organ systems including the skeleton (tall stature, lanky build, chest wall deformities, curved spine, long arms and legs, long fingers), eyes (lens dislocation), lungs (collapsed lung), the heart and aorta. An echocardiogram is used to evaluate an enlargement of the aortic root, a bulge in the wall of the body’s largest blood vessel at the point where it exits the heart. This bulge is one of the most dangerous complications of Marfan syndrome. It allows the aortic valve to leak blood back into the heart, and if the aorta tears or bursts it is life-threatening. Which features occur varies by individual, and even among family members affected with Marfan the features may vary. The severity of the condition also varies from hardly noticeable to severe or life-threatening. So while a tall, thin body and especially long legs, arms and fingers are typical signs, a diagnosis can’t be made from visual inspection alone. Genetic testing is highly accurate for diagnosing Marfan syndrome, with the genetic mutation that causes it (in the FBN1 gene) found in most people with diagnostic features of the condition. Marfan syndrome has a very high “penetrance”—meaning that when someone has the abnormal gene, he or she typically also has the diagnostic features. However, the features may be subtle and are not always striking. Although there is a familial genetic component to the risk of having Marfan—you have a 50% chance of having the condition if one of your parents has or had it—in at least 25% of diagnosed cases there is no family history of the disorder because it stems from a spontaneous genetic mutation. The parents of your cousin who has been diagnosed with Marfan syndrome should be tested. If neither parent has the same mutation as your cousin, then he has it because of a spontaneous mutation, and no other relatives would have to be evaluated. If either of your cousin’s parents is found to have Marfan, then all of your cousins’ siblings should also be checked—and it raises the possibility that your parent who is a sibling of your aunt or uncle with Marfan might also have inherited it. If so, whether you need to be tested is a question that’s best to take up with your doctor—who then can point you to a specialist, such as a geneticist, if appropriate. Important: When a person with Marfan syndrome is deciding whether to have children, it is very helpful to consult a genetic counselor, who can discuss the emotional and practical implications. Women with Marfan should discuss their plans with a cardiologist before getting pregnant, since pregnancy puts extra strain on the aorta. Unfortunately, there isn’t a cure for Marfan syndrome, but early diagnosis gives the best opportunity for patients to take care of what can be treated. Interventions such as blood pressure medication, heart surgery for aortic aneurysm, orthopedic procedures for skeletal abnormalities, and vision correction (because Marfan can lead to dislocation of the lens of the eye) help many people with Marfan live long and happy lives.
