Identification of a novel pathogenic variant in FBN1 associated with Marfan Syndrome.

Aortic diseases arising in Marfan Syndrome (MFS), such as in aneurysms and dissections of the thoracic aorta, are related to genetic alterations in the FBN1 gene. Databases, such as Universal Mutations-FBN1, ClinVar and The Human Gene Mutation, contain more than a thousand FBN1 mutations associated with MFS. The FBN1 gene, which encodes fibrillin-1, is responsible for the integral production of different protein domains. Possible genetic changes may lead to a weakening of blood vessels, leading to the development of aortopathies. In this study, we present the association of a novel FBN1 variant with MFS. The proband is a man who presented ascending aortic aneurysm and dissection (TAAD) at 42-yr-old, which was surgically treated. Clinical investigations were performed in all family members enrolled in the study. Marfan signs were observed in the proband, daughters and granddaughter. Direct sequencing of the FBN1 gene in the proband identified a novel truncation variant p.(Glu2019Ter) and a cascade screening were done. The variant was classified as pathogenic and causal for MFS according to the American College of Medical Genetics and Genomics (ACMG) criteria and revised Ghent nosology for MFS diagnosis, respectively. Proband's daughter and granddaughter harbor the variant, however without aortic alteration. This work reports for the first time a patient with the FBN1-p.(Glu2019Ter) variant and its association with MFS/TAAD.