What Is It?
Marfan syndrome is a genetic (inherited) disorder that affects the body's connective tissue. Connective tissue is the tough, fibrous, elastic tissue that connects one part of the body with another. It is a major part of tendons, ligaments, bones, cartilage and the walls of large blood vessels. In Marfan syndrome, the body can't produce enough fibrillin, an important building block of connective tissue.
The problem in Marfan syndrome is caused by a mutation (change) in a gene. Genes are segments of DNA that direct the body to produce proteins. In many families with inherited Marfan syndrome, the mutation affects the FBN1 gene on chromosome 15, although a second gene on chromosome 5 may be involved in some cases.