According to the last revised Ghent criteria for MFS diagnosis, the identification of FBN1 pathogenetic mutation in the proband, exhibiting aortic root dilatation (Z-score >2), allowed diagnosing MFS [8], and the identification of FBN1 mutations in proband's mother also permitted diagnosing her as potential Marfan patient, even if with a less severe phenotype. The gene discussed is FBN1; the disease is Marfan syndrome.