FBLN5 and Marfan syndrome: The mRNA levels of several elastin fiber-related proteins were significantly higher in MFS patients compared with controls, including fibulin-5 (FBLN5), latent-transforming growth factor-β-binding protein 1 (LTBP1), and 4 (LTBP4) as well as MFAP4 (Figure 4A, Table V in the online-only Data Supplement).