For the first time, we demonstrate aberrant glycosylation alongside elevated levels of the FBN1-interacting MFAP4 (microfibril-associated glycoprotein 4) in MFS and provide evidence for the application of MFAP4 as a potential plasma biomarker to identify patients with MFS at risk for type B aortic dissection. This evidence concerns the gene MFAP4 and Marfan syndrome.