Causes

Marfan syndrome is caused by a defect in the gene that enables your body to produce a protein that helps give connective tissue its elasticity and strength.

Most people with Marfan syndrome inherit the abnormal gene from a parent who has the disorder. Each child of an affected parent has a 50-50 chance of inheriting the defective gene. In about 25% of the people who have Marfan syndrome, the abnormal gene comes from neither parent. In these cases, a new mutation develops spontaneously.