Definition of Marfan syndrome:

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.

Causes, incidence, and risk factors:

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.

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.

Other areas of the body that are affected include:

• Lung tissue
• The aorta, the main blood vessel that takes blood from the heart to the body may stretch or become weak (called aortic dilation or aortic aneurysm)
• The eyes, causing cataracts and other problems
• The skin
• Tissue covering the spinal cord

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.