FBN1 and Marfan syndrome: Additional murine models for Marfan syndrome include the Fbn1C1039G/C1039G model, in which mice have a missense mutation causing normal Fbn1 expression but aberrant fiber formation (86), and the Fbn1GT−8/GT−8 model, where Fibrillin-1 is truncated and has four-fold reduced expression (87).