Marfan syndrome is a disorder of connective tissue, the tissue that strengthens the body's structures. Disorders of connective tissue affect the skeletal system, cardiovascular system, eyes, and skin.

Marfan syndrome is caused by defects in a gene called fibrillin-1. Fibrillin-1 plays an important role as the building block for elastic tissue in the body.

A problem with this gene leads to changes in elastic tissues, particularly in the aorta, eye, and skin. The gene defect also causes too much growth of the long bones of the body. This causes the tall height and long arms and legs seen in people 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.

People with Marfan syndrome are usually tall with long, thin arms and legs and spider-like fingers -- a condition called arachnodactyly. When they stretch out their arms, the length of their arms is much greater than their height.

Other symptoms include:

• Coloboma of iris
• Flat feet
• Funnel chest (pectus excavatum) or pigeon breast (pectus carinatum)
• Highly arched palate and crowded teeth
• Hypotonia
• Learning disability
• Movement of the lens of the eye from its normal position (dislocation)
• Nearsightedness
• Scoliosis
• Small lower jaw (micrognathia)
• Thin, narrow face

The doctor will perform a physical exam. There may be hypermobile joints and signs of:

• Aneurysm
• Collapsed lung
• Heart valve problems

An eye exam may show:

• Defects of the lens or cornea
• Retinal detachment
• Vision problems

The following tests may be performed:

• Echocardiogram
• Fibrillin-1 mutation testing (in some people)

An echocardiogram should be done every year to look at the base of the aorta.