Marfan syndrome is a rare disorder. It causes a defect in the body’s connective tissue. This tissue is common throughout the body. It holds the body together and supports many of its structures. As a result Marfan syndrome affects many organ systems, including:

  • Skeleton—particularly joints
  • Lungs
  • Eyes
  • Heart and blood vessels

Marfan syndrome is caused by a defect in a gene. The gene controls a protein needed to build connective tissue.

In almost all cases, the defective gene is passed from a parent. In very rare cases, the defect can be caused by a mutation.