Marfan's syndrome is inherited. 

It is caused by a change in the fibrillin-1 or FBN1 gene.  This gene makes fibrilin, which is a proten that makes elastic fibers in your connective tissue. 

It is an autosomnal dominant inheritance, meaning it is a dominant gene.  Only 1 copy of the allele needs to be inherited for a person to have Marfan's syndrome. 

It can be difficult to diagnose.  

Medical professionals will ask about your family medical history. 

There is normally a unique criteria used to diagnose MFS called the "Ghent nosology."

Diagnosis willl include CT scans, chest X-rays, heart tests, and MRIs.

Genetic testing can also be helpful.