What Causes Marfan Syndrome?

Marfan syndrome is caused by a defect (mutation) in the gene that tells the body how to make fibrillin-1 -- a protein that is an important part of connective tissue. 

This defect results in an increase in a protein called transforming growth factor beta, or TGFβ.  The increase of TGFβ causes problems in tissue throughout the body, which create the different Marfan syndrome features and cause medical problems for people with Marfan syndrome.

People can inherit Marfan syndrome, meaning that they get the mutation from a parent who has the disorder. This is the case in about 3 out of 4 people with Marfan syndrome. Other people have a spontaneous mutation, meaning that they are the first in their family to have Marfan syndrome. People with Marfan syndrome have a 50-50 chance of passing the mutation on each time they have a child.

People are born with Marfan syndrome but may not notice any features until later in life.  Marfan syndrome features can appear at any age, including in infants and young children.  They may get worse as people age.