The NM_000138.5 c.7540G>A is a missense variant in FBN1 predicted to cause a substitution of a glycine acid by arginine at amino acid 2514 (p.Gly2514Arg), located within a calcium binding EGF-like (cbEGF) domain of the protein. This variant was found in a proband with thoracic aortic aneurysm and ectopia lentis which is a highly specific phenotype for Marfan syndrome (internal data-Bichat) (PP4). This variant has been reported in at least 4 individuals with thoracic aortic aneurysm and/or clinical features of Marfan syndrome (PMID 26272055, 19720936, 11875032, Laboratory for Molecular Medicine ClinVarentry), and in at least 3 individuals clinically diagnosed with Marfan syndrome (PMID 33483584, 28468757, Rurali et al. 2019) (PS4). It was also found to segregate with the disease in at least 5 affected family members from multiple families (Rurali et al. 2019, Laboratory for Molecular Medicine ClinVar entry, internal data) (PP1_Strong). This variant is not present in gnomAD (PM2_sup; https://gnomad.broadinstitute.org/ version 2.1.1). Computational prediction tools and conservation analysis suggest that this variant may impact the protein (REVEL: 0.945) (PP3). The constraint z-score for missense variants affecting FBN1 is 5.06 (PP2). In summary, this variant meets criteria to be classified as pathogenic for Marfan syndrome based on the ACMG/AMP criteria applied, as specified by the ClinGen FBN1 VCEP: PS4, PP1_Strong, PM2_Sup, PP2, PP3, PP4