FBN1 and Marfan syndrome: Marfan syndrome (MFS, OMIM #154700) is a common genetic disorder that affects mainly connective tissues, due to heterozygous mutations in FBN1, a relatively large gene (230 kb long) composed of 65 exons located on the long arm of chromosome 15 (15q21.1) that encodes for Fibrillin-1, a protein component of the Extracellular Matrix (ECM) [1].