What Causes Marfan Syndrome?

Marfan syndrome is caused by a defect in the gene that controls the structure of a protein called fibrillin 1. Fibrillin 1 is an important part of connective tissue. If you have the defective gene, your body produces fibrillin 1 that does not function as it should. As a result, your connective tissue is not as strong as it should be, and it weakens over time. Fibrillin 1 also plays a role in the growth and development of many of the organs of the body. Defective fibrillin 1 contributes to the tall, thin body type seen in people with Marfan syndrome, as well as other Marfan signs and symptoms.

About 3 out of 4 people with Marfan syndrome inherit the defective gene from a parent. In about 1 out of every 4 people with Marfan syndrome, the gene abnormality occurs due to a chance (spontaneous) mutation of the gene.