@article {708, title = {Genetic and molecular mechanism for distinct clinical phenotypes conveyed by allelic truncating mutations implicated in FBN1.}, journal = {Mol Genet Genomic Med}, volume = {8}, year = {2020}, month = {2020 01}, pages = {e1023}, abstract = {

BACKGROUND: The molecular and genetic mechanisms by which different single nucleotide variant alleles in specific genes, or at the same genetic locus, cause distinct disease phenotypes often remain unclear. Allelic truncating mutations of FBN1 could cause either classical Marfan syndrome (MFS) or a more complicated phenotype associated with Marfanoid-progeroid-lipodystrophy syndrome (MPLS).

METHODS: We investigated a small cohort, encompassing two classical MFS and one MPLS subjects~from China, whose clinical presentation included scoliosis potentially requiring surgical intervention. Targeted next generation sequencing was performed on all the participants. We analyzed the molecular diagnosis, clinical features, and the potential molecular mechanism involved in the MPLS subject in our cohort.

RESULTS: We report a novel de novo FBN1 mutation for the first Chinese subject~with MPLS, a more complicated fibrillinopathy, and two subjects~with more classical MFS. We further predict that the MPLS truncating mutation, and others previously reported, is prone to escape the nonsense-mediated decay (NMD), while MFS mutations are predicted to be subjected to NMD. Also, the MPLS mutation occurs within the glucogenic hormone asprosin domain of FBN1. In vitro experiments showed that the single MPLS mutation p.Glu2759Cysfs*9 appears to perturb proper FBN1 protein aggregation as compared with the~classical MFS mutation p.Tyr2596Thrfs*86. Both mutations appear to upregulate SMAD2 phosphorylation in vitro.

CONCLUSION: We provide direct evidence that a dominant-negative interaction of FBN1 potentially explains the complex MPLS phenotypes through genetic and functional analysis. Our study expands the mutation spectrum of FBN1 and highlights the potential molecular mechanism for MPLS.

}, keywords = {Adolescent, Adult, Child, Female, Fibrillin-1, HEK293 Cells, Humans, Lipodystrophy, Marfan Syndrome, Mutation, Phenotype, Progeria, Protein Domains, Smad2 Protein}, issn = {2324-9269}, doi = {10.1002/mgg3.1023}, author = {Lin, Mao and Liu, Zhenlei and Liu, Gang and Zhao, Sen and Li, Chao and Chen, Weisheng and Coban Akdemir, Zeynep and Lin, Jiachen and Song, Xiaofei and Wang, Shengru and Xu, Qiming and Zhao, Yanxue and Wang, Lianlei and Zhang, Yuanqiang and Yan, Zihui and Liu, Sen and Liu, Jiaqi and Chen, Yixin and Zuo, Yuzhi and Yang, Xu and Sun, Tianshu and Yang, Xin-Zhuang and Niu, Yuchen and Li, Xiaoxin and You, Wesley and Qiu, Bintao and Ding, Chen and Liu, Pengfei and Zhang, Shuyang and Carvalho, Claudia M B and Posey, Jennifer E and Qiu, Guixing and Lupski, James R and Wu, Zhihong and Zhang, Jianguo and Wu, Nan} } @article {111, title = {Pathogenic FBN1 variants in familial thoracic aortic aneurysms and dissections.}, journal = {Clin Genet}, volume = {89}, year = {2016}, month = {2016 06}, pages = {719-23}, abstract = {

Marfan syndrome (MFS) due to mutations in FBN1 is a known cause of thoracic aortic aneurysms and acute aortic dissections (TAAD) associated with pleiotropic manifestations. Genetic predisposition to TAAD can also be inherited in families in the absence of syndromic features, termed familial TAAD (FTAAD), and several causative genes have been identified to date. FBN1 mutations can also be identified in FTAAD families, but the frequency of these mutations has not been established. We performed exome sequencing of 183 FTAAD families and identified pathogenic FBN1 variants in five (2.7\%) of these families. We also identified eight additional FBN1 rare variants that could not be unequivocally classified as disease-causing in six families. FBN1 sequencing should be considered in individuals with FTAAD even without significant systemic features of MFS.

}, keywords = {Adult, Aged, Aneurysm, Dissecting, Aortic Aneurysm, Thoracic, Exome, Family Health, Female, Fibrillin-1, Genetic Predisposition to Disease, Humans, Male, Marfan Syndrome, Middle Aged, Mutation, Pedigree, Sequence Analysis, DNA}, issn = {1399-0004}, doi = {10.1111/cge.12702}, author = {Regalado, E S and Guo, D C and Santos-Cortez, R L P and Hostetler, E and Bensend, T A and Pannu, H and Estrera, A and Safi, H and Mitchell, A L and Evans, J P and Leal, S M and Bamshad, M and Shendure, J and Nickerson, D A and Milewicz, D M} } @article {188, title = {FBN1 contributing to familial congenital diaphragmatic hernia.}, journal = {Am J Med Genet A}, volume = {167A}, year = {2015}, month = {2015 Apr}, pages = {831-6}, abstract = {

Congenital diaphragmatic hernia (CDH) is a relatively common, life--threatening birth defect. We present a family with recurrent CDH--paraesophageal and central--for whom exome sequencing (ES) revealed a frameshift mutation (c.4969_4970insA, p.Ile1657Asnfs*30) in the fibrillin 1 gene (FBN1) that causes Marfan syndrome. A diagnosis of Marfan syndrome had not been considered previously in this family. However, a review of the literature demonstrated that FBN1 mutations have an unusual pattern of CDH in which paraesophageal hernias are particularly common. Subsequent clinical evaluations revealed evidence for ectopia lentis in affected family members supporting a clinical diagnosis of Marfan syndrome. Since only two other cases of familial CDH have been described in association with FBN1 mutations, we investigated an oligogenic hypothesis by examining ES data for deleterious sequence changes in other CDH-related genes. This search revealed putatively deleterious sequence changes in four other genes that have been shown to cause diaphragm defects in humans and/or mice--FREM1, DES, PAX3 and MET. It is unclear whether these changes, alone or in aggregate, are contributing to the development of CDH in this family. However, their individual contribution is likely to be small compared to that of the frameshift mutation in FBN1. We conclude that ES can be used to identify both major and minor genetic factors that may contribute to CDH. These results also suggest that ES should be considered in the diagnostic evaluation of individuals and families with CDH, particularly when other diagnostic modalities have failed to reveal a molecular etiology.

}, keywords = {Adult, Child, Preschool, DNA Mutational Analysis, Exome, Female, Fibrillin-1, Fibrillins, Frameshift Mutation, Genetic Association Studies, Hernias, Diaphragmatic, Congenital, Humans, Male, Marfan Syndrome, Microfilament Proteins, Pedigree}, issn = {1552-4833}, doi = {10.1002/ajmg.a.36960}, author = {Beck, Tyler F and Campeau, Philippe M and Jhangiani, Shalini N and Gambin, Tomasz and Li, Alexander H and Abo-Zahrah, Reem and Jordan, Valerie K and Hernandez-Garcia, Andres and Wiszniewski, Wojciech K and Muzny, Donna and Gibbs, Richard A and Boerwinkle, Eric and Lupski, James R and Lee, Brendan and Reardon, Willie and Scott, Daryl A} } @article {324, title = {Loss-of-function mutations in TGFB2 cause a syndromic presentation of thoracic aortic aneurysm.}, journal = {Nat Genet}, volume = {44}, year = {2012}, month = {2012 Jul 08}, pages = {922-7}, abstract = {

Loeys-Dietz syndrome (LDS) associates with a tissue signature for high transforming growth factor (TGF)-β signaling but is often caused by heterozygous mutations in genes encoding positive effectors of TGF-β signaling, including either subunit of the TGF-β receptor or SMAD3, thereby engendering controversy regarding the mechanism of disease. Here, we report heterozygous mutations or deletions in the gene encoding the TGF-β2 ligand for a phenotype within the LDS spectrum and show upregulation of TGF-β signaling in aortic tissue from affected individuals. Furthermore, haploinsufficient Tgfb2(+/-) mice have aortic root aneurysm and biochemical evidence of increased canonical and noncanonical TGF-β signaling. Mice that harbor both a mutant Marfan syndrome (MFS) allele (Fbn1(C1039G/+)) and Tgfb2 haploinsufficiency show increased TGF-β signaling and phenotypic worsening in association with normalization of TGF-β2 expression and high expression of TGF-β1. Taken together, these data support the hypothesis that compensatory autocrine and/or paracrine events contribute to the pathogenesis of TGF-β-mediated vasculopathies.

}, keywords = {Animals, Aortic Aneurysm, Thoracic, Disease Models, Animal, Female, Fibrillin-1, Fibrillins, Haploinsufficiency, Humans, Loeys-Dietz Syndrome, Male, Marfan Syndrome, Mice, Mice, Knockout, Mice, Mutant Strains, Microfilament Proteins, Mutation, Pedigree, Phenotype, Signal Transduction, Syndrome, Transforming Growth Factor beta2}, issn = {1546-1718}, doi = {10.1038/ng.2349}, author = {Lindsay, Mark E and Schepers, Dorien and Bolar, Nikhita Ajit and Doyle, Jefferson J and Gallo, Elena and Fert-Bober, Justyna and Kempers, Marlies J E and Fishman, Elliot K and Chen, Yichun and Myers, Loretha and Bjeda, Djahita and Oswald, Gretchen and Elias, Abdallah F and Levy, Howard P and Anderlid, Britt-Marie and Yang, Margaret H and Bongers, Ernie M H F and Timmermans, Janneke and Braverman, Alan C and Canham, Natalie and Mortier, Geert R and Brunner, Han G and Byers, Peter H and Van Eyk, Jennifer and Van Laer, Lut and Dietz, Harry C and Loeys, Bart L} } @article {319, title = {Mutations in the TGF-β repressor SKI cause Shprintzen-Goldberg syndrome with aortic aneurysm.}, journal = {Nat Genet}, volume = {44}, year = {2012}, month = {2012 Nov}, pages = {1249-54}, abstract = {

Elevated transforming growth factor (TGF)-β signaling has been implicated in the pathogenesis of syndromic presentations of aortic aneurysm, including Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS). However, the location and character of many of the causal mutations in LDS intuitively imply diminished TGF-β signaling. Taken together, these data have engendered controversy regarding the specific role of TGF-β in disease pathogenesis. Shprintzen-Goldberg syndrome (SGS) has considerable phenotypic overlap with MFS and LDS, including aortic aneurysm. We identified causative variation in ten individuals with SGS in the proto-oncogene SKI, a known repressor of TGF-β activity. Cultured dermal fibroblasts from affected individuals showed enhanced activation of TGF-β signaling cascades and higher expression of TGF-β-responsive genes relative to control cells. Morpholino-induced silencing of SKI paralogs in zebrafish recapitulated abnormalities seen in humans with SGS. These data support the conclusions that increased TGF-β signaling is the mechanism underlying SGS and that high signaling contributes to multiple syndromic presentations of aortic aneurysm.

}, keywords = {Animals, Aortic Aneurysm, Arachnodactyly, Cells, Cultured, Craniosynostoses, DNA-Binding Proteins, Fibroblasts, Humans, Loeys-Dietz Syndrome, Marfan Syndrome, Mice, Mutation, Phenotype, Phosphorylation, Proto-Oncogene Proteins, Signal Transduction, Transforming Growth Factor beta, Zebrafish}, issn = {1546-1718}, doi = {10.1038/ng.2421}, author = {Doyle, Alexander J and Doyle, Jefferson J and Bessling, Seneca L and Maragh, Samantha and Lindsay, Mark E and Schepers, Dorien and Gillis, Elisabeth and Mortier, Geert and Homfray, Tessa and Sauls, Kimberly and Norris, Russell A and Huso, Nicholas D and Leahy, Dan and Mohr, David W and Caulfield, Mark J and Scott, Alan F and Destr{\'e}e, Anne and Hennekam, Raoul C and Arn, Pamela H and Curry, Cynthia J and Van Laer, Lut and McCallion, Andrew S and Loeys, Bart L and Dietz, Harry C} }