Publications by authors named "Pauline Arnaud"

25 Publications

  • Page 1 of 1

Clinical relevance of genotype-phenotype correlations beyond vascular events in a cohort study of 1500 Marfan syndrome patients with FBN1 pathogenic variants.

Genet Med 2021 Mar 17. Epub 2021 Mar 17.

Université de Paris, LVTS, INSERM U1148, Hôpital Bichat-Claude-Bernard, Paris, France.

Purpose: Marfan syndrome (MFS) is a connective tissue disorder in which several systems are affected with great phenotypic variability. Although known to be associated with pathogenic variants in the FBN1 gene, few genotype-phenotype correlations have been found in proband studies only.

Methods: In 1,575 consecutive MFS probands and relatives from the most comprehensive database worldwide, we established survival curves and sought genotype-phenotype correlations.

Results: A risk chart could be established with clinical and genetic data. Premature termination codon variants were not only associated with a shorter life expectancy and a high lifelong risk of aortic event, but also with the highest risk of severe scoliosis and a lower risk for ectopia lentis (EL) surgery. In-frame variants could be subdivided according to their impact on the cysteine content of fibrillin-1 with a global higher severity for cysteine loss variants and the highest frequency of EL surgery for cysteine addition variants.

Conclusion: This study shows that FBN1 genotype-phenotype correlations exist for both aortic and extra-aortic features. It can be used for optimal risk stratification of patients with a great importance for genetic counseling and personalized medicine. This also provides additional data for the overall understanding of the role of fibrillin-1 in various organs.
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http://dx.doi.org/10.1038/s41436-021-01132-xDOI Listing
March 2021

Unsuspected somatic mosaicism for FBN1 gene contributes to Marfan syndrome.

Genet Med 2021 Jan 25. Epub 2021 Jan 25.

Université de Paris, Laboratory for Vascular Translational Science, INSERM U1148, Hôpital Bichat-Claude-Bernard, Paris, France.

Purpose: Individuals with mosaic pathogenic variants in the FBN1 gene are mainly described in the course of familial screening. In the literature, almost all these mosaic individuals are asymptomatic. In this study, we report the experience of our team on more than 5,000 Marfan syndrome (MFS) probands.

Methods: Next-generation sequencing (NGS) capture technology allowed us to identify five cases of MFS probands who harbored a mosaic pathogenic variant in the FBN1 gene.

Results: These five sporadic mosaic probands displayed classical features usually seen in Marfan syndrome. Combined with the results of the literature, these rare findings concerned both single-nucleotide variants and copy-number variations.

Conclusion: This underestimated finding should not be overlooked in the molecular diagnosis of MFS patients and warrants an adaptation of the parameters used in bioinformatics analyses. The five present cases of symptomatic MFS probands harboring a mosaic FBN1 pathogenic variant reinforce the fact that apparently asymptomatic mosaic parents should have a complete clinical examination and a regular cardiovascular follow-up. We advise that individuals with a typical MFS for whom no single-nucleotide pathogenic variant or exon deletion/duplication was identified should be tested by NGS capture panel with an adapted variant calling analysis.
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http://dx.doi.org/10.1038/s41436-020-01078-6DOI Listing
January 2021

Pathogenic variants in THSD4, encoding the ADAMTS-like 6 protein, predispose to inherited thoracic aortic aneurysm.

Genet Med 2021 Jan 28;23(1):111-122. Epub 2020 Aug 28.

Laboratory for Vascular Translational Science, INSERM U1148, Université de Paris, Centre Hospitalo-Universitaire Xavier Bichat, APHP, Paris, France.

Purpose: Thoracic aortic aneurysm and dissection (TAAD) is a life-threatening disease with often unrecognized inherited forms. We sought to identify novel pathogenic variants associated with autosomal dominant inheritance of TAAD.

Methods: We analyzed exome sequencing data from 35 French TAAD families and performed next-generation sequencing capture panel of genes in 1114 unrelated TAAD patients. Functional effects of pathogenic variants identified were validated in cell, tissue, and mouse models.

Results: We identified five functional variants in THSD4 of which two heterozygous variants lead to a premature termination codon. THSD4 encodes ADAMTSL6 (member of the ADAMTS/L superfamily), a microfibril-associated protein that promotes fibrillin-1 matrix assembly. The THSD4 variants studied lead to haploinsufficiency or impaired assembly of fibrillin-1 microfibrils. Thsd4 mice showed progressive dilation of the thoracic aorta. Histologic examination of aortic samples from a patient carrying a THSD4 variant and from Thsd4 mice, revealed typical medial degeneration and diffuse disruption of extracellular matrix.

Conclusion: These findings highlight the role of ADAMTSL6 in aortic physiology and TAAD pathogenesis. They will improve TAAD management and help develop new targeted therapies.
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http://dx.doi.org/10.1038/s41436-020-00947-4DOI Listing
January 2021

Quantifying the Genetic Basis of Marfan Syndrome Clinical Variability.

Genes (Basel) 2020 05 20;11(5). Epub 2020 May 20.

INSERM U1148, 75018 Paris, France.

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder with considerable inter- and intra-familial clinical variability. The contribution of inherited modifiers to variability has not been quantified. We analyzed the distribution of 23 clinical features in 1306 well-phenotyped MFS patients carrying mutations. We found strong correlations between features within the same system (i.e., ophthalmology vs. skeletal vs. cardiovascular) suggesting common underlying determinants, while features belonging to different systems were largely uncorrelated. We adapted a classical quantitative genetics model to estimate the heritability of each clinical feature from phenotypic correlations between relatives. Most clinical features showed strong familial aggregation and high heritability. We found a significant contribution by the major locus on the phenotypic variance only for ectopia lentis using a new strategy. Finally, we found evidence for the "Carter effect" in the MFS cardiovascular phenotype, which supports a polygenic model for MFS cardiovascular variability and indicates additional risk for children of MFS mothers with an aortic event. Our results demonstrate that an important part of the phenotypic variability in MFS is under the control of inherited modifiers, widely shared between features within the same system, but not among different systems. Further research must be performed to identify genetic modifiers of MFS severity.
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http://dx.doi.org/10.3390/genes11050574DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7288268PMC
May 2020

Excess of de novo variants in genes involved in chromatin remodelling in patients with marfanoid habitus and intellectual disability.

J Med Genet 2020 07 10;57(7):466-474. Epub 2020 Apr 10.

Centre de Compétence Anomalies du Développement et Syndromes Malformatifs Sud-Est, CHI de Toulon - La Seyne-sur-Mer, France.

Purpose: Marfanoid habitus (MH) combined with intellectual disability (ID) (MHID) is a clinically and genetically heterogeneous presentation. The combination of array CGH and targeted sequencing of genes responsible for Marfan or Lujan-Fryns syndrome explain no more than 20% of subjects.

Methods: To further decipher the genetic basis of MHID, we performed exome sequencing on a combination of trio-based (33 subjects) or single probands (31 subjects), of which 61 were sporadic.

Results: We identified eight genes with de novo variants (DNVs) in at least two unrelated individuals ( and ). Using simulation models, we showed that five genes ( and ) met conservative Bonferroni genomewide significance for an excess of the observed de novo point variants. Overall, at least one pathogenic or likely pathogenic variant was identified in 54.7% of subjects (35/64). These variants fell within 27 genes previously associated with Mendelian disorders, including and , which are known to be mutated in overgrowth syndromes.

Conclusion: We demonstrated that DNVs were enriched in chromatin remodelling (p=2×10) and genes regulated by the fragile X mental retardation protein (p=3×10), highlighting overlapping genetic mechanisms between MHID and related neurodevelopmental disorders.
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http://dx.doi.org/10.1136/jmedgenet-2019-106425DOI Listing
July 2020

A Case of Trisomy 13 Mosaicism Presenting with a Severe Aortic Root Dilatation and Marfanoid Habitus due to an Unpredictable Cytogenetic Mechanism.

Cytogenet Genome Res 2020 18;160(2):72-79. Epub 2020 Mar 18.

In this report, we present a new case of mosaic trisomy 13 with prolonged survival, firstly detected by array-CGH analysis which was carried out because of moderate intellectual disability with postaxial hexadactyly, dermatologic features, ventricular septal defect, bicuspid aortic valve, and aortic dystrophy in a 19-year-old male patient. In a subset of 15% of the cells, the patient carried a derivative chromosome 10 generated by a nonreciprocal (10;13) translocation inherited from his healthy mother who carried the translocation in a balanced and homogeneous state. FISH analyses showed interstitial telomeric sequences at the breakpoints. To our knowledge, this is the second report of a patient with trisomy 13 mosaicism displaying a severe aortic root dilatation. We also discuss the mechanisms which could explain the mosaic state, the most likely one being related to the instability of the interstitial telomere.
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http://dx.doi.org/10.1159/000506319DOI Listing
April 2020

Clinical and genetic data of 22 new patients with SMAD3 pathogenic variants and review of the literature.

Mol Genet Genomic Med 2020 05 10;8(5):e1132. Epub 2020 Mar 10.

Service de génétique médicale, Hôpital Purpan, CHU de Toulouse, Toulouse, France.

Background: Pathogenic SMAD3 variants are responsible for a cardiovascular phenotype, mainly thoracic aortic aneurysms and dissections. Precocious identification of the vascular risk such as aortic dilatation in mutated patients has a major impact in terms of management, particularly to avoid dissection and sudden death. These vascular damages are classically associated with premature osteoarthritis and skeletal abnormalities. However, variable expressivity and incomplete penetrance are common with SMAD3 variants.

Methods: To investigate the clinical variability observed within SMAD3 patients, we reviewed the phenotypic and genetic data of 22 new patients from our Centre and of 133 patients reported in the literature. From this cohort of 155 mutated individuals, we first aimed to delineate an estimated frequency of the main clinical signs associated with SMAD3 pathogenic variants and, then, to look for genotype-phenotype correlations, mainly to see if the aortic phenotype (AP) could be predicted by the SMAD3 variant type.

Results: We showed, herein, the absence of correlation between the SMAD3 variant type and the occurrence of an AP in patients.

Conclusion: Therefore, this report brings additional data for the genotype-phenotype correlations of SMAD3 variants and the need to explore in more detail the effects of genetic modifiers that could influence the phenotype.
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http://dx.doi.org/10.1002/mgg3.1132DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7216810PMC
May 2020

Pathogenic FBN1 Genetic Variation and Aortic Dissection in Patients With Marfan Syndrome.

J Am Coll Cardiol 2020 03;75(8):843-853

Centre de référence pour le syndrome de Marfan et apparentés, VASCERN HTAD European Reference Center, AP-HP, Hôpital Bichat, Paris, France; INSERM U1148, LVTS, Hôpital Bichat, Paris, France; Université de Paris, Paris, France. Electronic address:

Background: Aortic risk has not been evaluated in patients with Marfan syndrome and documented pathogenic variants in the FBN1 gene.

Objectives: This study sought to describe aortic risk in a population with Marfan syndrome with pathogenic variants in the FBN1 gene as a function of aortic root diameter.

Methods: Patients carrying an FBN1 pathogenic variant who visited our reference center at least twice were included, provided they had not undergone aortic surgery or had an aortic dissection before their first visit. Aortic events (aortic surgery or aortic dissection) and deaths were evaluated during the 2 years following each patient visit. The risk was calculated as the number of events divided by the number of years of follow-up.

Results: A total of 954 patients were included (54% women; mean age 23 years). During follow-up (9.1 years), 142 patients underwent prophylactic aortic root surgery, 5 experienced type A aortic dissection, and 12 died (noncardiovascular causes in 3, unknown etiology in 3, post-operative in 6). When aortic root diameter was <50 mm, risk for proven type A dissection (0.4 events/1,000 patient-years) and risk for possible aortic dissection (proven aortic dissection plus death of unknown cause, 0.7 events/1,000 patients-years) remained low in this population that was treated according to guidelines. Three type A aortic dissections occurred in this population during the 8,594 years of follow-up, including 1 in a patient with a tubular aortic diameter of 50 mm, but none in patients with a family history of aortic dissection. The risk for type B aortic dissection in the same population was 0.5 events/1,000 patient-years.

Conclusions: In patients with FBN1 pathogenic variants who receive beta-blocker therapy and who limit strenuous exercise, aortic risk remains low when maximal aortic diameter is <50 mm. The risk of type B aortic dissection is close to the remaining risk of type A aortic dissection in this population, which underlines the global aortic risk.
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http://dx.doi.org/10.1016/j.jacc.2019.12.043DOI Listing
March 2020

A new mutational hotspot in the SKI gene in the context of MFS/TAA molecular diagnosis.

Hum Genet 2020 Apr 24;139(4):461-472. Epub 2020 Jan 24.

Centre de Génétique et Centre de Référence Anomalies du Développement et Syndromes Malformatifs de l'interrégion Est et FHU TRANSLAD, Hôpital d'Enfants, Centre Hospitalier Universitaire Dijon, 14, Rue Gaffarel, 21079, Dijon Cedex, France.

SKI pathogenic variations are associated with Shprintzen-Goldberg Syndrome (SGS), a rare systemic connective tissue disorder characterized by craniofacial, skeletal and cardiovascular features. So far, the clinical description, including intellectual disability, has been relatively homogeneous, and the known pathogenic variations were located in two different hotspots of the SKI gene. In the course of diagnosing Marfan syndrome and related disorders, we identified nine sporadic probands (aged 2-47 years) carrying three different likely pathogenic or pathogenic variants in the SKI gene affecting the same amino acid (Thr180). Seven of these molecular events were confirmed de novo. All probands displayed a milder morphological phenotype with a marfanoid habitus that did not initially lead to a clinical diagnosis of SGS. Only three of them had learning disorders, and none had intellectual disability. Six out of nine presented thoracic aortic aneurysm, which led to preventive surgery in the oldest case. This report extends the phenotypic spectrum of variants identified in the SKI gene. We describe a new mutational hotspot associated with a marfanoid syndrome with no intellectual disability. Cardiovascular involvement was confirmed in a significant number of cases, highlighting the importance of accurately diagnosing SGS and ensuring appropriate medical treatment and follow-up.
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http://dx.doi.org/10.1007/s00439-019-02102-9DOI Listing
April 2020

Phenotypic spectrum of TGFB3 disease-causing variants in a Dutch-French cohort and first report of a homozygous patient.

Clin Genet 2020 05 16;97(5):723-730. Epub 2020 Jan 16.

Département de Génétique, Assistance Publique-Hôpitaux de Paris, Hôpital Bichat, Paris, France.

Disease-causing variants in TGFB3 cause an autosomal dominant connective tissue disorder which is hard to phenotypically delineate because of the small number of identified cases. The purpose of this retrospective cross-sectional multicenter study is to elucidate the genotype and phenotype in an international cohort of TGFB3 patients. Eleven (eight novel) TGFB3 disease-causing variants were identified in 32 patients (17 families). Aortic root dilatation and mitral valve disease represented the most common cardiovascular findings, reported in 29% and 32% of patients, respectively. Dissection involving distal aortic segments occurred in two patients at age 50 and 52 years. A high frequency of systemic features (65% high-arched palate, 63% arachnodactyly, 57% pectus deformity, 52% joint hypermobility) was observed. In familial cases, incomplete penetrance and variable clinical expressivity were noted. Our cohort included the first described homozygous patient, who presented with a more severe phenotype compared to her heterozygous relatives. In conclusion, TGFB3 variants were associated with a high percentage of systemic features and aortic disease (dilatation/dissection) in 35% of patients. No deaths occurred from cardiovascular events or pregnancy-related complications. Nevertheless, homozygosity may be driving a more severe phenotype.
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http://dx.doi.org/10.1111/cge.13700DOI Listing
May 2020

Systems pharmacology-based integration of human and mouse data for drug repurposing to treat thoracic aneurysms.

JCI Insight 2019 06 6;4(11). Epub 2019 Jun 6.

Department of Pharmacological Sciences and Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, New York, USA.

Marfan syndrome (MFS) is associated with mutations in fibrillin-1 that predispose afflicted individuals to progressive thoracic aortic aneurysm (TAA) leading to dissection and rupture of the vessel wall. Here we combined computational and experimental approaches to identify and test FDA-approved drugs that may slow or even halt aneurysm progression. Computational analyses of transcriptomic data derived from the aortas of MFS patients and MFS mice (Fbn1mgR/mgR mice) predicted that subcellular pathways associated with reduced muscle contractility are key TAA determinants that could be targeted with the GABAB receptor agonist baclofen. Systemic administration of baclofen to Fbn1mgR/mgR mice validated our computational prediction by mitigating arterial disease progression at the cellular and physiological levels. Interestingly, baclofen improved muscle contraction-related subcellular pathways by upregulating a different set of genes than those downregulated in the aorta of vehicle-treated Fbn1mgR/mgR mice. Distinct transcriptomic profiles were also associated with drug-treated MFS and wild-type mice. Thus, systems pharmacology approaches that compare patient- and mouse-derived transcriptomic data for subcellular pathway-based drug repurposing represent an effective strategy to identify potential new treatments of human diseases.
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http://dx.doi.org/10.1172/jci.insight.127652DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6629138PMC
June 2019

Reference Expression Profile of Three Transcript Isoforms and Their Association with Clinical Variability in Marfan Syndrome.

Genes (Basel) 2019 02 11;10(2). Epub 2019 Feb 11.

Laboratory for Vascular Translational Science, INSERM U1148, Centre Hospitalo-Universitaire Xavier Bichat, 46 rue Henri Huchard, 75018 Paris, France.

Marfan syndrome (MFS) is a rare connective tissue disorder mainly due to mutations in the gene. Great phenotypic variability is notable for age of onset, the presence and absence, and the number and the severity of the symptoms. Our team showed that gene expression level was a good surrogate endpoint for severity of some MFS clinical features. Eight alternative transcripts are referenced for the gene. We hypothesized that MFS clinical variability could be related to specific isoforms. Isoform expression profiles were investigated in skin and adventitial fibroblasts from controls and MFS patients. The results of the study showed that, in skin and adventitial fibroblasts, only three isoforms were found: , , and . The main isoform was and it was significantly reduced in skin and adventitial fibroblasts of MFS patients. The expressions of and isoforms were similar between controls and MFS patients. However, the expression of the three isoforms was correlated only in patients. Furthermore, their expression levels were associated with the presence of ectopia lentis in MFS patients. Therefore, our results highlight that the two minor alternatively spliced isoforms play a possible role in the pathogenesis of the disease.
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http://dx.doi.org/10.3390/genes10020128DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6409622PMC
February 2019

Genetic diversity and pathogenic variants as possible predictors of severity in a French sample of nonsyndromic heritable thoracic aortic aneurysms and dissections (nshTAAD).

Genet Med 2019 09 11;21(9):2015-2024. Epub 2019 Feb 11.

Hôpital Bichat, Département de Génétique, Assistance Publique-Hôpitaux de Paris, Paris, France.

Purpose: Heritable thoracic aortic aneurysms and dissections (hTAAD) are life-threatening complications of well-known syndromic diseases or underdiagnosed nonsyndromic heritable forms (nshTAAD). Both have an autosomal dominant transmission and are genetically heterogeneous. Our objective was to describe the relevance of molecular diagnosis in these patients and the contribution of each gene in nshTAAD.

Methods: Two hundred twenty-six consecutive nshTAAD probands, either young (<45 years) sporadic or familial cases were included. A next-generation sequencing capture panel comprising 23 known disease-causing genes was performed.

Results: Class 4 or 5 variants were identified in 18% of the nshTAAD probands, while class 3 variants were found in 10% of them. The yield in familial cases was greater than in sporadic cases. SMAD3 and FBN1 genes were the major disease-causing genes. Unexpectedly, no premature termination codon variant was identified in the FBN1 gene. Furthermore, we report for the first time that aortic dissection or surgery occurred significantly more often and earlier in probands with a class 4 or 5 pathogenic variant.

Conclusion: This study indicates that genetic screening using NGS is efficient in young and familial nshTAAD. The presence of a pathogenic variant has a possible predictive value, which needs to be further investigated because it may influence care.
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http://dx.doi.org/10.1038/s41436-019-0444-yDOI Listing
September 2019

pathogenic variants: risk for thoracic aortic disease and associated complications from the Montalcino Aortic Consortium.

J Med Genet 2019 04 19;56(4):252-260. Epub 2019 Jan 19.

Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, USA.

Background: Pathogenic variants in cause thoracic aortic aneurysms and dissections, along with aneurysms and rupture of other arteries. Here, we examined differences in clinical presentation of aortic events (dissection or surgical repair of an aneurysm) with respect to age and variant type in an international cohort of individuals with variants.

Methods: Aortic status and events, vital status and clinical features were abstracted through retrospective review of medical records of 212 individuals with 51 unique variants, including haploinsufficiency (HI) and missense substitutions in the MH2 domain, as well as novel in-frame deletions and missense variants in the MH1 domain.

Results: Aortic events were documented in 37% of cases, with dissections accounting for 70% of events. The median age at first aortic event was significantly lower in individuals with MH2 missense variants than those with HI variants (42years vs 49 years; p=0.003), but there was no difference in frequency of aortic events by variant type. The cumulative risk of an aortic event was 50% at 54 years of age. No aortic events in childhood were observed.

Conclusions: pathogenic variants cause thoracic aortic aneurysms and dissections in the majority of individuals with variable age of onset and reduced penetrance. Of the covariates examined, the type of underlying variant was responsible for some of this variation. Later onset of aortic events and the absence of aortic events in children associated with variants support gene-specific management of this disorder.
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http://dx.doi.org/10.1136/jmedgenet-2018-105583DOI Listing
April 2019

Marfan Syndrome Variability: Investigation of the Roles of Sarcolipin and Calcium as Potential Transregulator of FBN1 Expression.

Genes (Basel) 2018 Aug 21;9(9). Epub 2018 Aug 21.

Laboratory for Vascular Translational Science, INSERM U1148, Centre Hospitalo-Universitaire Xavier Bichat, 46 rue Henri Huchard, 75018 Paris, France.

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder that displays a great clinical variability. Previous work in our laboratory showed that fibrillin-1 () messenger RNA (mRNA) expression is a surrogate endpoint for MFS severity. Therefore, an expression quantitative trait loci (eQTL) analysis was performed to identify trans-acting regulators of expression, and a significant signal reached genome-wide significant threshold on chromosome 11. This signal delineated a region comprising one expressed gene, (encoding sarcolipin), and a single pseudogene, (CTD-2651C21.3). We first investigated the region and then looked for association between the genes in the region and expression. For the first time, we showed that the gene is weakly expressed in skin fibroblasts. There is no direct correlation between and gene expression. We showed that calcium influx modulates gene expression. Finally, gene expression is highly correlated to that of the neighboring . We were able to confirm the impact of calcium influx on gene expression but we could not conclude regarding the role of sarcolipin and/or the eQTL locus in this regulation.
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http://dx.doi.org/10.3390/genes9090421DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6162465PMC
August 2018

Association of modifiers and other genetic factors explain Marfan syndrome clinical variability.

Eur J Hum Genet 2018 12 7;26(12):1759-1772. Epub 2018 Aug 7.

Laboratory for Vascular Translational Science, INSERM U1148, DHU FIRE, Centre Hospitalo-Universitaire Xavier Bichat (APHP), 46 rue Henri Huchard, Paris, 75018, France.

Marfan syndrome (MFS) is a rare autosomal dominant connective tissue disorder related to variants in the FBN1 gene. Prognosis is related to aortic risk of dissection following aneurysm. MFS clinical variability is notable, for age of onset as well as severity and number of clinical manifestations. To identify genetic modifiers, we combined genome-wide approaches in 1070 clinically well-characterized FBN1 disease-causing variant carriers: (1) an FBN1 eQTL analysis in 80 fibroblasts of FBN1 stop variant carriers, (2) a linkage analysis, (3) a kinship matrix association study in 14 clinically concordant and discordant sib-pairs, (4) a genome-wide association study and (5) a whole exome sequencing in 98 extreme phenotype samples.Three genetic mechanisms of variability were found. A new genotype/phenotype correlation with an excess of loss-of-cysteine variants (P = 0.004) in severely affected subjects. A second pathogenic event in another thoracic aortic aneurysm gene or the COL4A1 gene (known to be involved in cerebral aneurysm) was found in nine individuals. A polygenic model involving at least nine modifier loci (named gMod-M1-9) was observed through cross-mapping of results. Notably, gMod-M2 which co-localizes with PRKG1, in which activating variants have already been described in thoracic aortic aneurysm, and gMod-M3 co-localized with a metalloprotease (proteins of extra-cellular matrix regulation) cluster. Our results represent a major advance in understanding the complex genetic architecture of MFS and provide the first steps toward prediction of clinical evolution.
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http://dx.doi.org/10.1038/s41431-018-0164-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6244213PMC
December 2018

Clinical Validity of Genes for Heritable Thoracic Aortic Aneurysm and Dissection.

J Am Coll Cardiol 2018 08;72(6):605-615

Center for Medical Genetics, Ghent University Hospital, Ghent, Belgium; Department of Cardiology, Ghent University Hospital, Ghent, Belgium. Electronic address:

Background: Thoracic aortic aneurysms progressively enlarge and predispose to acute aortic dissections. Up to 25% of individuals with thoracic aortic disease harbor an underlying Mendelian pathogenic variant. An evidence-based strategy for selection of genes to test in hereditary thoracic aortic aneurysm and dissection (HTAAD) helps inform family screening and intervention to prevent life-threatening thoracic aortic events.

Objectives: The purpose of this study was to accurately identify genes that predispose to HTAAD using the Clinical Genome Resource (ClinGen) framework.

Methods: We applied the semiquantitative ClinGen framework to assess presumed gene-disease relationships between 53 candidate genes and HTAAD. Genes were classified as causative for HTAAD if they were associated with isolated thoracic aortic disease and were clinically actionable, triggering routine aortic surveillance, intervention, and family cascade screening. All gene-disease assertions were evaluated by a pre-defined curator-expert pair and subsequently discussed with an expert panel.

Results: Genes were classified based on the strength of association with HTAAD into 5 categories: definitive (n = 9), strong (n = 2), moderate (n = 4), limited (n = 15), and no reported evidence (n = 23). They were further categorized by severity of associated aortic disease and risk of progression. Eleven genes in the definitive and strong groups were designated as "HTAAD genes" (category A). Eight genes were classified as unlikely to be progressive (category B) and 4 as low risk (category C). The remaining genes were recent genes with an uncertain classification or genes with no evidence of association with HTAAD.

Conclusions: The ClinGen framework is useful to semiquantitatively assess the strength of gene-disease relationships for HTAAD. Gene categories resulting from the curation may inform clinical laboratories in the development, interpretation, and subsequent clinical implications of genetic testing for patients with aortic disease.
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http://dx.doi.org/10.1016/j.jacc.2018.04.089DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6378369PMC
August 2018

MYLK pathogenic variants aortic disease presentation, pregnancy risk, and characterization of pathogenic missense variants.

Genet Med 2019 01 20;21(1):144-151. Epub 2018 Jun 20.

Department of Internal Medicine, McGovern Medical School, University of Texas Health Science Center at Houston, Houston, Texas, USA.

Purpose: Heritable thoracic aortic disease can result from null variants in MYLK, which encodes myosin light-chain kinase (MLCK). Data on which MYLK missense variants are pathogenic and information to guide aortic disease management are limited.

Methods: Clinical data from 60 cases with MYLK pathogenic variants were analyzed (five null and two missense variants), and the effect of missense variants on kinase activity was assessed.

Results: Twenty-three individuals (39%) experienced an aortic event (defined as aneurysm repair or dissection); the majority of these events (87%) were aortic dissections. Aortic diameters were minimally enlarged at the time of dissection in many cases. Time-to-aortic-event curves showed that missense pathogenic variant (PV) carriers have earlier-onset aortic events than null PV carriers. An MYLK missense variant segregated with aortic disease over five generations but decreases MYLK kinase acitivity marginally. Functional Assays fail to identify all pathogenic variants in MYLK.

Conclusion: These data further define the aortic phenotype associated with MYLK pathogenic variants. Given minimal aortic enlargement before dissection, an alternative approach to guide the timing of aortic repair is proposed based on the probability of a dissection at a given age.
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http://dx.doi.org/10.1038/s41436-018-0038-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6400320PMC
January 2019

Development and Validation of a New Scoring System to Predict Survival in Patients With Myotonic Dystrophy Type 1.

JAMA Neurol 2018 05;75(5):573-581

Cardiology Department, Cochin Hospital, Filière Neuromusculaire, Paris-Descartes University, Sorbonne Paris Cité University, Assistance Publique-Hôpitaux de Paris, Paris, France.

Importance: Life expectancy is greatly shortened in patients presenting with myotonic dystrophy type 1 (DM1), the most common neuromuscular disease. A reliable prediction of survival in patients with DM1 is critically important to plan personalized health supervision.

Objective: To develop and validate a prognostic score to predict 10-year survival in patients with DM1.

Design, Setting, And Participants: In this longitudinal cohort study, between January 2000 and November 2014, we enrolled 1296 adults referred to 4 tertiary neuromuscular centers in France for management of genetically proven DM1, including 1066 patients in the derivation cohort and 230 in the validation cohort. Data were analyzed from December 2016 to March 2017.

Main Outcomes And Measures: Factors associated with survival by multiple variable Cox modeling, including 95% confidence intervals, and development of a predictive score validated internally and externally. Mean values are reported with their standard deviations.

Results: Of the 1296 included patients, 670 (51.7%) were women, and the mean (SD) age was 39.8 (13.7) years. Among the 1066 patients (82.3%) in the derivation cohort, 241 (22.6%) died over a median (interquartile range) follow-up of 11.7 (7.7-14.3) years. Age, diabetes, need for support when walking, heart rate, systolic blood pressure, first-degree atrioventricular block, bundle-branch block, and lung vital capacity were associated with death. Simplified score points were attributed to each predictor, and adding these points yielded scores between 0 and 20, with 0 indicating the lowest and 20 the highest risk of death. The 10-year survival rate was 96.6% (95% CI, 94.4-98.9) in the group with 0 to 4 points, 92.2% (95% CI, 88.8-95.6) in the group with 5 to 7 points, 80.7% (95% CI, 75.4-86.1) in the group with 8 to 10 points, 57.9% (95% CI, 49.2-66.6) in the group with 11 to 13 points, and 19.4% (95% CI, 8.6-30.1) in the group with 14 points or more. In 230 patients (17.7%) included in the validation cohort, the 10-year survival rates for the groups with 0 to 4, 5 to 7, 8 to 10, 11 to 13, and 14 points or more were 99.3% (95% CI, 95.0-100), 80.6% (95% CI, 67.1-96.7), 79.3% (95% CI, 66.2-95.1), 43.2% (95% CI, 28.2-66.1), and 21.6% (95% CI, 10.0-46.8), respectively. The calibration curves did not deviate from the reference line. The C index was 0.753 (95% CI, 0.722-0.785) in the derivation cohort and 0.806 (95% CI, 0.758-0.855) in the validation cohort.

Conclusions And Relevance: The DM1 prognostic score is associated with long-term survival.
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http://dx.doi.org/10.1001/jamaneurol.2017.4778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5885178PMC
May 2018

Association Between Mutation Size and Cardiac Involvement in Myotonic Dystrophy Type 1: An Analysis of the DM1-Heart Registry.

Circ Cardiovasc Genet 2017 Jun;10(3)

Background: In myotonic dystrophy type 1, the association between mutation size (CTG expansion) and the severity of cardiac involvement is controversial.

Methods And Results: We selected 855 patients with myotonic dystrophy type 1 (women, 51%; median age, 37 years), with genetic testing performed at the moment of their initial cardiac evaluation, out of 1014 patients included in the Myotonic Dystrophy Type 1-Heart Registry between January 2000 and December 2015. We studied the association between CTG expansion size and other baseline characteristics and (1) cardiac involvement at baseline and (2) the incidence of death, sudden death, and other cardiac adverse events. At initial presentation, the median CTG expansion size was 530 (interquartile range, 300-830). In multivariate analysis, larger expansions were associated with the presence at baseline of conduction defects on the ECG and left ventricular systolic dysfunction. In a median 11.5 years of follow-up period, 210 patients died (25%), including 32 suddenly (4%). Supraventricular arrhythmias developed over lifetime in 166 patients (19%), sustained ventricular tachyarrhythmias in 17 (2%), and permanent pacemakers were implanted in 181 (21%). In Cox regression analyses, larger CTG expansions were significantly associated with (1) total death, sudden death, and pacemaker implantation in a model, including CTG expansion size, age, sex, diabetes mellitus, and (2) all end points except sudden death in a model including all baseline characteristics.

Conclusions: The size of the CTG expansion in the blood of myotonic dystrophy type 1 patients is associated with total and sudden deaths, conduction defects, left ventricular dysfunction, and supraventricular arrhythmias.

Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique Identifier: NCT01136330.
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http://dx.doi.org/10.1161/CIRCGENETICS.116.001526DOI Listing
June 2017

WES/WGS Reporting of Mutations from Cardiovascular "Actionable" Genes in Clinical Practice: A Key Role for UMD Knowledgebases in the Era of Big Databases.

Hum Mutat 2016 12 10;37(12):1308-1317. Epub 2016 Oct 10.

Aix Marseille Univ,  INSERM, GMGF, Marseille, France.

High-throughput next-generation sequencing such as whole-exome and whole-genome sequencing are being rapidly integrated into clinical practice. The use of these techniques leads to the identification of secondary variants for which decisions about the reporting or not to the patient need to be made. The American College of Medical Genetics and Genomics recently published recommendations for the reporting of these variants in clinical practice for 56 "actionable" genes. Among these, seven are involved in Marfan Syndrome And Related Disorders (MSARD) resulting from mutations of the FBN1, TGFBR1 and 2, ACTA2, SMAD3, MYH11 and MYLK genes. Here, we show that mutations collected in UMD databases for MSARD genes (UMD-MSARD) are rarely reported, including the most frequent ones, in global scale initiatives for variant annotation such as the NHLBI GO Exome Sequencing Project (ESP), the Exome Aggregation Consortium (ExAC), and ClinVar. The predicted pathogenic mutations reported in global scale initiatives but absent in locus-specific databases (LSDBs) mainly correspond to rare events. UMD-MSARD databases are therefore the only resources providing access to the full spectrum of known pathogenic mutations. They are the most comprehensive resources for clinicians and geneticists to interpret MSARD-related variations not only primary variants but also secondary variants.
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http://dx.doi.org/10.1002/humu.23119DOI Listing
December 2016

Actionable Genes, Core Databases, and Locus-Specific Databases.

Hum Mutat 2016 12 26;37(12):1299-1307. Epub 2016 Sep 26.

Aix Marseille Univ, INSERM, GMGF, Marseille, France.

Adoption of next-generation sequencing (NGS) in a diagnostic context raises numerous questions with regard to identification and reports of secondary variants (SVs) in actionable genes. To better understand the whys and wherefores of these questioning, it is necessary to understand how they are selected during the filtering process and how their proportion can be estimated. It is likely that SVs are underestimated and that our capacity to label all true SVs can be improved. In this context, Locus-specific databases (LSDBs) can be key by providing a wealth of information and enabling classifying variants. We illustrate this issue by analyzing 318 SVs in 23 actionable genes involved in cancer susceptibility syndromes identified through sequencing of 572 participants selected for a range of atherosclerosis phenotypes. Among these 318 SVs, only 43.4% are reported in Human Gene Mutation Database (HGMD) Professional versus 71.4% in LSDB. In addition, 23.9% of HGMD Professional variants are reported as pathogenic versus 4.8% for LSDB. These data underline the benefits of LSDBs to annotate SVs and minimize overinterpretation of mutations thanks to their efficient curation process and collection of unpublished data.
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http://dx.doi.org/10.1002/humu.23112DOI Listing
December 2016

Homozygous and compound heterozygous mutations in the FBN1 gene: unexpected findings in molecular diagnosis of Marfan syndrome.

J Med Genet 2017 02 31;54(2):100-103. Epub 2016 Aug 31.

Département de Génétique et Centre de Référence Maladies Rares Syndrome de Marfan et pathologies apparentées, Assistance Publique-Hôpitaux de Paris, Hôpital Bichat, Paris, France.

Background: Marfan syndrome (MFS) is an autosomal-dominant connective tissue disorder usually associated with heterozygous mutations in the gene encoding fibrillin-1 (FBN1). Homozygous and compound heterozygous cases are rare events and have been associated with a clinical severe presentation.

Objectives: Report unexpected findings of homozygosity and compound heterozygosity in the course of molecular diagnosis of heterozygous MFS and compare the findings with published cases.

Methods And Results: In the context of molecular diagnosis of heterozygous MFS, systematic sequencing of the FBN1 gene was performed in 2500 probands referred nationwide. 1400 probands carried a heterozygous mutation in this gene. Unexpectedly, among them four homozygous cases (0.29%) and five compound heterozygous cases (0.36%) were identified (total: 0.64%). Interestingly, none of these cases carried two premature termination codon mutations in the FBN1 gene. Clinical features for these carriers and their families were gathered and compared. There was a large spectrum of severity of the disease in probands carrying two mutated FBN1 alleles, but none of them presented extremely severe manifestations of MFS in any system compared with carriers of only one mutated FBN1 allele. This observation is not in line with the severe clinical features reported in the literature for four homozygous and three compound heterozygous probands.

Conclusion: Homozygotes and compound heterozygotes were unexpectedly identified in the course of molecular diagnosis of MFS. Contrary to previous reports, the presence of two mutated alleles was not associated with severe forms of MFS. Although homozygosity and compound heterozygosity are rarely found in molecular diagnosis, they should not be overlooked, especially among consanguineous families. However, no predictive evaluation of severity should be provided.
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http://dx.doi.org/10.1136/jmedgenet-2016-103996DOI Listing
February 2017

Neonatal Marfan Syndrome: Report of a Case with an Inherited Splicing Mutation outside the Neonatal Domain.

Mol Syndromol 2016 Feb 2;6(6):281-6. Epub 2016 Feb 2.

Génétique Médicale, CHU de Nantes, Université de Nantes, Nantes, France.

We report a child and her mother affected by Marfan syndrome. The child presented with a phenotype of neonatal Marfan syndrome, revealed by acute and refractory heart failure, finally leading to death within the first 4 months of life. Her mother had a common clinical presentation. Genetic analysis revealed an inherited FBN1 mutation. This intronic mutation (c.6163+3_6163+6del), undescribed to date, leads to exon 49 skipping, corresponding to in-frame deletion of 42 amino acids (p.Ile2014_Asp2055del). FBN1 next-generation sequencing did not show any argument for mosaicism. Association in the same family of severe neonatal and classical Marfan syndrome illustrates the intrafamilial phenotype variability.
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http://dx.doi.org/10.1159/000443867DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4802997PMC
February 2016

LOX Mutations Predispose to Thoracic Aortic Aneurysms and Dissections.

Circ Res 2016 Mar 12;118(6):928-34. Epub 2016 Jan 12.

From the Departments of Internal Medicine (D.G., E.S.R., L.G., X.D., Z.R., B.C., E.M.H., D.M.M.) and Cardiothoracic and Vascular Surgery (A.E., H.J.S.), University of Texas Health Science Center, Houston; Department of Molecular and Human Genetics, Center for Statistical Genetics, Baylor College of Medicine, Houston, TX (R.L.P.S.-C., S.M.L.); Laboratory for Vascular Translational Science, INSERM U1148, Hôpital Bichat, Paris, France (P.A., G.J., C.B.); Centre National de Référence pour le syndrome de Marfan et apparentés, Département de Génétique Moléculaire, AP-HP, Hôpital Bichat, Paris, France (P.A., C.B.); Department of Pediatrics, MetroHealth Medical Center, Cleveland, OH (R.M.); Department of Medicine, Stanford University Medical Center, CA (D.L.); and Department of Genome Sciences, University of Washington, Seattle (M.J.B., J.S., D.A.N.).

Rationale: Mutations in several genes have been identified that are responsible for 25% of families with familial thoracic aortic aneurysms and dissections. However, the causative gene remains unknown in 75% of families.

Objectives: To identify the causative mutation in families with autosomal dominant inheritance of thoracic aortic aneurysms and dissections.

Methods And Results: Exome sequencing was used to identify the mutation responsible for a large family with thoracic aortic aneurysms and dissections. A heterozygous rare variant, c.839G>T (p.Ser280Arg), was identified in LOX, encoding a lysyl oxidase, that segregated with disease in the family. Sanger and exome sequencing was used to investigate mutations in LOX in an additional 410 probands from unrelated families. Additional LOX rare variants that segregated with disease in families were identified, including c.125G>A (p.Trp42*), c.604G>T (p.Gly202*), c.743C>T (p.Thr248Ile), c.800A>C (p.Gln267Pro), and c.1044T>A (p.Ser348Arg). The altered amino acids cause haploinsufficiency for LOX or are located at a highly conserved LOX catalytic domain, which is relatively invariant in the population. Expression of the LOX variants p.Ser280Arg and p.Ser348Arg resulted in significantly lower lysyl oxidase activity when compared with the wild-type protein. Individuals with LOX variants had fusiform enlargement of the root and ascending thoracic aorta, leading to ascending aortic dissections.

Conclusions: These data, along with previous studies showing that the deficiency of LOX in mice or inhibition of lysyl oxidases in turkeys and rats causes aortic dissections, support the conclusion that rare genetic variants in LOX predispose to thoracic aortic disease.
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http://dx.doi.org/10.1161/CIRCRESAHA.115.307130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4839295PMC
March 2016