In her two-part Casebook Appearances Can Be Deceptive Dr Child discussed the misleading mimics and disguised carriers of Marfan syndrome. Today she outlines the means of a definitive diagnosis.

The following are criteria that together may indicate a diagnosis of Marfan syndrome …

Signs and symptoms

Marfan syndrome (MFS) affects a variety of body systems. In particular, cardiac problems are of note in this population, as are skeletal abnormalities (especially the chest and hands), and problems with the eyes and vision. Marfan syndrome does not affect intelligence. The following are common problems in this syndrome (this list is not exhaustive).

Common clinical features of MFS:

• Enlargement of the root of the aorta (a portion of the aorta)
• Dissection of the aorta (tears in the internal wall of the aorta)
• Mitral valve prolapse (valve does not close properly)
• Other cardiovascular problems
• Joint laxity/hypermobility
• Acetabular protrusion (an abnormality of the acetabulum of the hip);
• Pectus excavatum (sunken chest) or carinatum (pigeon chest)
• Scoliosis or other spinal curvature abnormalities
• Dural ectasia (bulging of the spinal column lining)
• Flat feet
• Dislocation of the eye lens (ectopia lentis);
• Near-sightedness that may be severe
• Cataracts
• Stretch marks on the skin
• An arm-span that is greater than height

Two important clinical features of MFS are the wrist and thumb signs. The presence of these is an indicator for MFS, however these signs can occur on their own in a person who does not have MFS. Testing for them is simple. A thumb sign means that when a person makes a fist over the thumb, the thumb juts out beyond the wrapped fingers. A wrist sign means that a person's little finger and thumb overlap when wrapped around the wrist. These signs are part of the diagnostic criteria for MFS.

Facial features of Marfan syndrome (MFS)

Many people with MFS have a characteristic facial appearance. Many have a long face that is narrow, with underdeveloped cheek bones, a small lower jaw that recedes, and a highly arched palate. Some people also have eyes that appear to slant downward. These features can help with diagnosis, but they do not occur in all patients.