A novel truncating FBN1 variant in a family with Marfan syndrome.

Marfan syndrome is caused by pathogenic variants in FBN1. We identified a novel heterozygous frameshift variant in FBN1 (NM_000138.5: c.6784_6787del, NP_000129.3:p.(Gln2262TrpfsTer28)) in an adult male with severe cardiovascular manifestations. The variant was absent from population databases and fulfilled PVS1 and PM2 criteria. This finding expands the mutational and phenotypic spectrum of FBN1 and highlights the clinical utility of genetic testing in family-based clinical management of Marfan syndrome.