What Causes Marfan Syndrome?

Marfan syndrome is a genetic disorder. A mutation, or change, in the gene that controls how the body makes fibrillin causes Marfan syndrome. Fibrillin is a protein that plays a major role in your body's connective tissue.

Most people who have Marfan syndrome inherit the altered gene from a parent. If you have the disorder, each of your children has a 50 percent chance of having the altered gene.

In some cases, Marfan syndrome isn't inherited. The mutation in the fibrillin gene occurs in the egg or sperm cells. If a child is conceived, the altered gene may be passed on to the child. The chance of that child's brothers or sisters having Marfan syndrome is low.