FBN1 and Marfan syndrome: FBN1 mutations have been implicated in several hereditary connective tissue disorders, including Marfan syndrome (MFS; Dietz et al., 1991; Ramirez & Dietz, 2007), Weill–Marchesani syndrome (WMS; Faivre et al., 2003), and stiff skin syndrome (Loeys et al., 2010).