FBN1 and Marfan syndrome: While both the Fbn1mgR/mgR and the Fbn1C1039G/+ MFS mouse models continue to reveal tremendous insight into the impact and consequences of FBN1 mutations in the etiology of Marfan syndrome, there have not been any in vivo non-invasive echo studies of the clinical phenotype of these mice to determine the degree to which they recapitulate the human condition [20].