Medical Management of Marfan Syndrome

Updated 2022 ACC/AHA Guideline Improves Concordance Between TTE and CT in Monitoring Marfan Snydrome and Related Disorders, but Relevant Measurement Differences Remain Frequent

Background

Patients diagnosed with Marfan syndrome or a related syndrome require frequent aorta monitoring using imaging techniques like transthoracic echocardiography (TTE) and computed tomography (CT). Accurate aortic measurement is crucial, as even slight enlargement (>2 mm) often necessitates surgical intervention. The 2022 ACC/AHA guideline for Aortic Disease Diagnosis and Management includes updated imaging recommendations. We aimed to compare these with the 2010 guideline.

Methods

This retrospective study involved 137 patients with Marfan syndrome or a related disorder, undergoing TTE and ECG-triggered CT. Aortic diameter measurements were taken based on the old 2010 guideline (TTE: inner edge to inner edge, CT: external diameter) and the new 2022 guideline (TTE: leading edge to leading edge, CT: internal diameter). Bland-Altman plots compared measurement differences.

Results

Using the 2022 guideline significantly reduced differences outside the clinical agreement limit from 49% to 26% for the aortic sinus and from 41% to 29% for the ascending aorta. Mean differences were -0.30 mm for the aortic sinus and +1.12 mm for the ascending aorta using the 2022 guideline, compared to -2.66 mm and +1.21 mm using the 2010 guideline.

Conclusion

This study demonstrates for the first time that the 2022 ACC/AHA guideline improves concordance between ECG-triggered CT and TTE measurements in Marfan syndrome patients, crucial for preventing life-threatening aortic complications. However, the frequency of differences >2 mm remains high.

Clinical Relevance/Application

Accurate aortic diameter measurement is vital for patients at risk of fatal aortic complications. While the 2022 guideline enhances concordance between imaging modalities, frequent differences >2 mm persist, potentially impacting decisions on aortic repair. The risk of repeat radiation exposure from ECG-triggered CT, considered the 'gold standard', continues to be justified.

Regnase-1 overexpression as a therapeutic approach of Marfan syndrome

Rupture or dissection of thoracic aortic aneurysms is still the leading cause of death for patients diagnosed with Marfan syndrome. Inflammation and matrix digestion regulated by matrix metalloproteases (MMPs) play a major role in the pathological remodeling of the aortic media. Regnase-1 is an endoribonuclease shown to cleave the mRNA of proinflammatory cytokines, such as interleukin-6. Considering the major anti-inflammatory effects of regnase-1, here, we aimed to determine whether adeno-associated virus (AAV)-mediated vascular overexpression of the protein could provide protection from the development and progression of aortic aneurysms in Marfan syndrome. The overexpression of regnase-1 resulted in a marked decrease in inflammatory parameters and elastin degradation in aortic smooth muscle cells in vitro. Intravenous injection of a vascular-targeted AAV vector resulted in the efficient transduction of the aortic wall and overexpression of regnase-1 in a murine model of Marfan syndrome, associated with lower circulating levels of proinflammatory cytokines and decreased MMP expression and activity. Regnase-1 overexpression strongly improved elastin architecture in the media and reduced aortic diameter at distinct locations. Therefore, AAV-mediated regnase-1 overexpression may represent a novel gene therapy approach for inhibiting aortic aneurysms in Marfan syndrome.

The Antioxidant/Nitric Oxide-Quenching Agent Cobinamide Prevents Aortic Disease in a Mouse Model of Marfan Syndrome

Major pathologic changes in the proximal aorta underlie the life-threatening aortic aneurysms and dissections in Marfan Syndrome; current treatments delay aneurysm development without addressing the primary pathology. Because excess oxidative stress and nitric oxide/protein kinase G signaling likely contribute to the aortopathy, we hypothesized that cobinamide, a strong antioxidant that can attenuate nitric oxide signaling, could be uniquely suited to prevent aortic disease. In a well-characterized mouse model of Marfan Syndrome, cobinamide dramatically reduced elastin breaks, prevented excess collagen deposition and smooth muscle cell apoptosis, and blocked DNA, lipid, and protein oxidation and excess nitric oxide/protein kinase G signaling in the ascending aorta. Consistent with preventing pathologic changes, cobinamide diminished aortic root dilation without affecting blood pressure. Cobinamide exhibited excellent safety and pharmacokinetic profiles indicating it could be a practical treatment. We conclude that cobinamide deserves further study as a disease-modifying treatment of Marfan Syndrome.

Drug-based cardiovascular prevention in patients with Marfan Syndrome: a systematic review

INTRODUCTION

Marfan Syndrome (MFS) is a rare and complex genetic disorder associated with increased aortic growth and aortic disease. The effectiveness of cardiovascular medical therapies aiming to slow down aortic growth has been tested in several trials, particularly beta-blockers and angiotensin receptor blockers, however showing conflicting results.

EVIDENCE ACQUISITION

We conducted a systematic review on PubMed (Medline), Cochrane library, Google Scholar, and Biomed Central databases between January and February 2022. We selected relevant articles focusing on patients with MFS treated with beta-blockers, angiotensin receptors blockers, or both, and reporting data on the effect of the drugs on 1) slowing down aortic dilatation; 2) the reduction of aortic complication (aortic dissection, mortality, aortic surgery); and with a 3) follow-up length of at least two years. A total of 16 studies were selected.

EVIDENCE SYNTHESIS

Beta-blockers remain the mainstay of therapy as they have proven to slow aortic enlargement. Angiotensin receptor blockers are a useful alternative and with proven benefit as an add-on therapy to limit aortic growth. Neither beta-blockers, nor angiotensin receptor blockers have shown meaningful results on clinical aortic endpoints.

CONCLUSIONS

The current evidence of pharmacological treatment for MFS patients is conflicting due to the lack of large, randomized clinical trials with adequate follow-up studies and homogeneous age grouping. Beta-blockers and angiotensin receptor blockers are the only available treatments to reduce aortic growth. A recently published patient-level meta-analysis confirmed that angiotensin receptor blockers and beta-blockers have a similar effect on reducing the rate of increase of the aortic root Z score, used singularly or as add-on therapy. Considering the current evidence on new features related with MFS (such as mitral annular disjunction - MAD) bearing a potential additional increased arrhythmic risk, it is of paramount importance to establish the role of beta-blockers and angiotensin receptor blockers in clinical endpoints of this population as well.

Comprehensive review of aortic aneurysms, dissections, and cardiovascular complications in connective tissue disorders

Connective tissue disorders, including Marfan syndrome (MS) and Ehlers-Danlos syndrome (EDS), are characterized by genetic mutations affecting connective tissue structural integrity. These disorders significantly elevate the risk of aortic dissection, a life-threatening condition. This comprehensive review delves into the intricate interplay between connective tissue disorders and aortic dissection, shedding light on the clinical features, pathophysiology, genetic underpinnings, diagnostic approaches, clinical management, associated comorbidities, and prognosis, mainly focusing on MS and EDS, while also exploring rare connective tissue disorders and forms of cutis laxa contributing to aortic pathology.

Insights into elastic fiber fragmentation: Mechanisms and treatment of aortic aneurysm in Marfan syndrome

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder caused by mutations in fibrillin 1 (FBN1) gene. These mutations result in defects in the skeletal, ocular, and cardiovascular systems. Aortic aneurysm is the leading cause of premature mortality in untreated MFS patients. Elastic fiber fragmentation in the aortic vessel wall is a hallmark of MFS-associated aortic aneurysms. FBN1 mutations result in FBN1 fragments that also contribute to elastic fiber fragmentation. Although recent research has advanced our understanding of MFS, the contribution of elastic fiber fragmentation to the pathogenesis of aneurysm formation remains poorly understood. This review provides a comprehensive overview of the molecular mechanisms of elastic fiber fragmentation and its role in the pathogenesis of aortic aneurysm progression. Increased comprehension of elastic fragmentation has significant clinical implications for developing targeted interventions to block aneurysm progression, which would benefit not only individuals with Marfan syndrome but also other patients with aneurysms. Moreover, this review highlights an overlooked connection between inhibiting aneurysm and the restoration of elastic fibers in the vessel wall with various aneurysm inhibitors, including drugs and chemicals. Investigating the underlying molecular mechanisms could uncover innovative therapeutic strategies to inhibit elastin fragmentation and prevent the progression of aneurysms.

Prophylactic effect of angiotensin receptor blockers in children with genetic aortopathies: the early bird catches the worm

AIMS

In genetic aortopathies (GA) particular attention is paid to aortic root dilatation which has an impact on morbidity and mortality. This study focuses on the effects of therapy with angiotensin-II-receptor-blockers (ARB) or beta-blockers (BB) on aortic root growth and the question which therapy should be initiated at which dosage and at what age.

METHODS

Since 1998 we diagnosed 208 patients with GA (170 FBN-1). 81 patients between 5 months and 18 years receiving either ARB or BB therapy were included. We retrospectively analyzed the progression of the dilatation of Sinus Valsalva aortae (SV) using calculated z-scores before and after therapy initiation and compared BB and ARB treatment.

RESULTS

Both ARB and BB (p < 0.05) therapy showed significant improvement in aortic root growth, while the effect is significantly more pronounced in ARB (p < 0.01) independent of age and genetic cause. A detailed comparison of the two drug groups showed a more sustained effect in limiting the progression of the dilatation of the aortic root in patients treated with ARB. Progression of dilatation of the SV was significantly lower in children treated with ARBs compared to BB (delta z-score, p < 0.05). In addition, ARBs were better tolerated and had a significantly lower discontinuation rate (3%) compared to BB (50%) (p < 0.01). Independently of age at initiation all children and adolescents were able to reach the target dose under ARB.

CONCLUSION

We demonstrated a significant change in both treatment options, with the effect of ARB being more pronounced while being better tolerated throughout the treatment period.

Long-Term Outcomes of Patients Undergoing Aortic Root Replacement With Mechanical Versus Bioprosthetic Valves: Meta-Analysis of Reconstructed Time-to-Event Data

Background An aspect not so clear in the scenario of aortic surgery is how patients fare after composite aortic valve graft replacement (CAVGR) depending on the type of valve (bioprosthetic versus mechanical). We performed a study to evaluate the long-term outcomes of both strategies comparatively. Methods and Results Pooled meta-analysis of Kaplan-Meier-derived time-to-event data from studies with follow-up for overall survival (all-cause death), event-free survival (composite end point of cardiac death, valve-related complications, stroke, bleeding, embolic events, and/or endocarditis), and freedom from reintervention. Twenty-three studies met our eligibility criteria, including 11 428 patients (3786 patients with mechanical valves and 7642 patients with bioprosthetic valve). The overall population was mostly composed of men (mean age, 45.5-75.6 years). In comparison with patients who underwent CAVGR with bioprosthetic valves, patients undergoing CAVGR with mechanical valves presented no statistically significant difference in the risk of all-cause death in the first 30 days after the procedure (hazard ratio [HR], 1.24 [95% CI, 0.95-1.60]; P=0.109), but they had a significantly lower risk of all-cause mortality after the 30-day time point (HR, 0.89 [95% CI, 0.81-0.99]; P=0.039) and lower risk of reintervention (HR, 0.33 [95% CI, 0.24-0.45]; P<0.001). Despite its increased risk for the composite end point in the first 6 years of follow-up (HR, 1.41 [95% CI, 1.09-1.82]; P=0.009), CAVGR with mechanical valves is associated with a lower risk for the composite end point after the 6-year time point (HR, 0.46 [95% CI, 0.31-0.67]; P<0.001). Conclusions CAVGR with mechanical valves is associated with better long-term outcomes in comparison with CAVGR with bioprosthetic valves.

Multi-omics in thoracic aortic aneurysm: the complex road to the simplification

BACKGROUND

Thoracic aortic aneurysm (TAA) is a serious condition that affects the aorta, characterized by the dilation of its first segment. The causes of TAA (e.g., age, hypertension, genetic syndromes) are heterogeneous and contribute to the weakening of the aortic wall. This complexity makes treating this life-threatening aortopathy challenging, as there are currently no etiological therapy available, and pharmacological strategies, aimed at avoiding surgical aortic replacement, are merely palliative. Recent studies on novel therapies for TAA have focused on identifying biological targets and etiological mechanisms of the disease by using advanced -omics techniques, including epigenomics, transcriptomics, proteomics, and metabolomics approaches.

METHODS

This review presents the latest findings from -omics approaches and underscores the importance of integrating multi-omics data to gain more comprehensive understanding of TAA.

RESULTS

Literature suggests that the alterations in TAA mediators frequently involve members of pro-fibrotic process (i.e., TGF-β signaling pathways) or proteins associated with cell/extracellular structures (e.g., aggrecans). Further analyses often reported the importance in TAA of processes as inflammation (PCR, CD3, leukotriene compounds), oxidative stress (chromatin OXPHOS, fatty acids), mitochondrial respiration and glycolysis/gluconeogenesis (e.g., PPARs and HIF1a). Of note, more recent metabolomics studies added novel molecular markers to the list of TAA-specific detrimental mediators (proteoglycans).

CONCLUSION

It is increasingly clear that integrating data from different -omics branches, along with clinical data, is essential as well as complicated both to reveal hidden relevant information and to address complex diseases such as TAA. Importantly, recent progresses in metabolomics highlighted novel potential and unprecedented marks in TAA diagnosis and therapy.

Marfan Syndrome beyond Aortic Root-Phenotyping Using Cardiovascular Magnetic Resonance Imaging and Clinical Implications

Marfan syndrome (MFS) is an inherited autosomal-dominant connective tissue disorder with multiorgan involvement including musculoskeletal, respiratory, cardiovascular, ocular, and skin manifestations. Life expectancy in patients with MFS is primarily determined by the degree of cardiovascular involvement. Aortic disease is the major cardiovascular manifestation of MFS. However, non-aortic cardiac diseases, such as impaired myocardial function and arrhythmia, have been increasingly acknowledged as additional causes of morbidity and mortality. We present two cases demonstrating the phenotypical variation in patients with MFS and how CMR (Cardiovascular Magnetic Resonance) could serve as a "one stop shop" to retrieveS all the necessary information regarding aortic/vascular pathology as well as any potential underlying arrhythmogenic substrate or cardiomyopathic process.

Fibroblasts in cancer: Unity in heterogeneity

Tumor cells do not exist in isolation in vivo, and carcinogenesis depends on the surrounding tumor microenvironment (TME), composed of a myriad of cell types and biophysical and biochemical components. Fibroblasts are integral in maintaining tissue homeostasis. However, even before a tumor develops, pro-tumorigenic fibroblasts in close proximity can provide the fertile 'soil' to the cancer 'seed' and are known as cancer-associated fibroblasts (CAFs). In response to intrinsic and extrinsic stressors, CAFs reorganize the TME enabling metastasis, therapeutic resistance, dormancy and reactivation by secreting cellular and acellular factors. In this review, we summarize the recent discoveries on CAF-mediated cancer progression with a particular focus on fibroblast heterogeneity and plasticity.

Generation of an induced pluripotent stem cell (iPSC) line of a Marfan syndrome patient with a pathogenic FBN1 c.5372G > A (p.Cys1791Tyr) variant

Marfan syndrome (MFS) is a connective tissue disorder with pleiotropic manifestations in the ocular, skeletal and cardiovascular system. Ruptured aortic aneurysms in MFS patients are associated with high mortality rates. MFS is typically caused by pathogenic variants in the fibrillin-1 (FBN1) gene. Here, we report a generated induced pluripotent cell (iPSC) line of a MFS patient with a FBN1 c.5372G > A (p.Cys1791Tyr) variant. For that, skin fibroblasts of a MFS patient carrying a FBN1 c.5372G > A (p.Cys1791Tyr) variant were successfully reprogrammed into iPSCs using the CytoTune™-iPS 2.0 Sendai Kit (Invitrogen). The iPSCs showed a normal karyotype, expressed pluripotency markers, were able to differentiate into three germ layers and carried the original genotype.

Correlation between large FBN1 deletions and severe cardiovascular phenotype in Marfan syndrome: Analysis of two novel cases and analytical review of the literature

BACKGROUND

Marfan syndrome (MFS) is a clinically heterogeneous hereditary connective tissue disorder. Severe cardiovascular manifestations (i.e., aortic aneurysm and dissection) are the most life-threatening complications. Most of the cases are caused by mutations, a minor group of which are copy number variations (CNV), in the FBN1 gene.

METHODS

Multiplex ligation-dependent probe amplification test was performed to detect CNVs in 41 MFS patients not carrying disease-causing mutations in FBN1 gene. Moreover, the association was analyzed between the localization of CNVs, the affected regulatory elements and the cardiovascular phenotypes among all cases known from the literature.

RESULTS

A large two-exon deletion (exon 46 and 47) was identified in two related patients, which was associated with a mild form of cardiovascular phenotype. Severe cardiovascular symptoms were found significantly more frequent in patients with FBN1 large deletion compared to our patients with intragenic small scale FBN1 mutation. Bioinformatic data analyses of regulatory elements located within the FBN1 gene revealed an association between the deletion of STAT3 transcription factor-binding site and cardiovascular symptoms in five out of 25 patients.

CONCLUSION

Our study demonstrated that large CNVs are often associated with severe cardiovascular manifestations in MFS and the localization of these CNVs affect the phenotype severity.

Pediatric Heart Network Trial of Losartan vs. Atenolol in Children and Young Adults with Marfan Syndrome: Impact on Prescription Practices

The Pediatric Heart Network (PHN) trial showed similar efficacy of β-blockers (BB) and angiotensin receptor blockers (ARB) for aortic root dilation in Marfan syndrome, but the impact on prescription practices is unknown. We hypothesized BB and ARB prescriptions would increase after the trial results were published (2014). Prescription data (2007-2016) were obtained from outpatient encounters (IBM Marketscan) for Marfan syndrome patients (6 months-25 years old). Excluding 2014 as a washout period, we analyzed two intervals: 2007-2013 and 2015-2016. Medication categories included BB, ARB, angiotensin converting enzyme inhibitors (ACEI), combination (BB/ARB and/or BB/ACEI), and no drug. Interrupted time-series analysis assessed immediate level change after publication and change in slope for the trend pre- and post-publication. Odds ratios (OR) and 95% confidence intervals from logistic regressions and generalized estimating equation methods accounted for correlation of prescriptions within patients. In 1499 patients (age 14.1 ± 6.1 years, 59% female) seen 2007-2013, BB trended lower [OR 0.91 (0.89, 0.93), p < 0.001] and ARB trended higher [OR 1.12 (1.07, 1.18), p < 0.001], while combination, ACEI, and no drug remained stable. This trend persisted, but was not significant, for BB [OR 0.54 (0.27, 1.08), p = 0.37] and ARB [OR 1.91 (0.55, 6.69), p = 0.31] in 2015-2016. Combination, ACEI, and no drug remained similar. In short term follow-up, changes in prescription practices following publication of the PHN trial were not statistically significant. This may be due to a change seen prior to publication with early adoption of ARBs that was maintained after confirmation of their effectiveness.

Allopurinol blocks aortic aneurysm in a mouse model of Marfan syndrome via reducing aortic oxidative stress

BACKGROUND

Increasing evidence indicates that redox stress participates in MFS aortopathy, though its mechanistic contribution is little known. We reported elevated reactive oxygen species (ROS) formation and NADPH oxidase NOX4 upregulation in MFS patients and mouse aortae. Here we address the contribution of xanthine oxidoreductase (XOR), which catabolizes purines into uric acid and ROS in MFS aortopathy.

METHODS AND RESULTS

In aortic samples from MFS patients, XOR protein expression, revealed by immunohistochemistry, increased in both the tunicae intima and media of the dilated zone. In MFS mice (Fbn1^C1041G/+), aortic XOR mRNA transcripts and enzymatic activity of the oxidase form (XO) were augmented in the aorta of 3-month-old mice but not in older animals. The administration of the XOR inhibitor allopurinol (ALO) halted the progression of aortic root aneurysm in MFS mice. ALO administrated before the onset of the aneurysm prevented its subsequent development. ALO also inhibited MFS-associated endothelial dysfunction as well as elastic fiber fragmentation, nuclear translocation of pNRF2 and increased 3'-nitrotyrosine levels, and collagen maturation remodeling, all occurring in the tunica media. ALO reduced the MFS-associated large aortic production of H₂O₂, and NOX4 and MMP2 transcriptional overexpression.

CONCLUSIONS

Allopurinol interferes in aortic aneurysm progression acting as a potent antioxidant. This study strengthens the concept that redox stress is an important determinant of aortic aneurysm formation and progression in MFS and warrants the evaluation of ALO therapy in MFS patients.

Discrepancy of echocardiography and computed tomography in initial assessment and 2-year follow-up for monitoring Marfan syndrome and related disorders

Patients with Marfan syndrome and related disorders are at risk for aortic dissection and aortic rupture and therefore require appropriate monitoring. Computed tomography (CT) and transthoracic echocardiography (TTE) are routinely used for initial diagnosis and follow-up. The purpose of this study is to compare whole-heart CT and TTE aortic measurement for initial work-up, 2-year follow-up, and detection of progressive aortic enlargement. This retrospective study included 95 patients diagnosed with Marfan syndrome or a related disorder. All patients underwent initial work-up including aortic diameter measurement using both electrocardiography-triggered whole-heart CT and TTE. Forty-two of these patients did not undergo aortic repair after initial work-up and were monitored by follow-up imaging within 2 years. Differences between the two methods for measuring aortic diameters were compared using Bland-Altman plots. The acceptable clinical limit of agreement (acLOA) for initial work-up, follow-up, and progression within 2 years was predefined as <  ± 2 mm. Bland-Altman analysis revealed a small bias of 0.2 mm with wide limits of agreement (LOA) from + 6.3 to - 5.9 mm for the aortic sinus and a relevant bias of - 1.6 mm with wide LOA from + 5.6 to - 8.9 mm for the ascending aorta. Follow-up imaging yielded a small bias of 0.5 mm with a wide LOA from + 6.7 to - 5.8 mm for the aortic sinus and a relevant bias of 1.1 mm with wide LOA from + 8.1 to - 10.2 mm for the ascending aorta. Progressive aortic enlargement at follow-up was detected in 57% of patients using CT and 40% of patients using TTE. Measurement differences outside the acLOA were most frequently observed for the ascending aorta. Whole-heart CT and TTE measurements show good correlation, but the frequency of measurement differences outside the acLOA is high. TTE systematically overestimates aortic diameters. Therefore, whole-heart CT may be preferred for aortic monitoring of patients with Marfan syndrome and related disorders. TTE remains an indispensable imaging tool that provides additional information not available with CT.

Angiotensin receptor blockers and β blockers in Marfan syndrome: an individual patient data meta-analysis of randomised trials

BACKGROUND

Angiotensin receptor blockers (ARBs) and β blockers are widely used in the treatment of Marfan syndrome to try to reduce the rate of progressive aortic root enlargement characteristic of this condition, but their separate and joint effects are uncertain. We aimed to determine these effects in a collaborative individual patient data meta-analysis of randomised trials of these treatments.

METHODS

In this meta-analysis, we identified relevant trials of patients with Marfan syndrome by systematically searching MEDLINE, Embase, and CENTRAL from database inception to Nov 2, 2021. Trials were eligible if they involved a randomised comparison of an ARB versus control or an ARB versus β blocker. We used individual patient data from patients with no prior aortic surgery to estimate the effects of: ARB versus control (placebo or open control); ARB versus β blocker; and indirectly, β blocker versus control. The primary endpoint was the annual rate of change of body surface area-adjusted aortic root dimension Z score, measured at the sinuses of Valsalva.

FINDINGS

We identified ten potentially eligible trials including 1836 patients from our search, from which seven trials and 1442 patients were eligible for inclusion in our main analyses. Four trials involving 676 eligible participants compared ARB with control. During a median follow-up of 3 years, allocation to ARB approximately halved the annual rate of change in the aortic root Z score (mean annual increase 0·07 [SE 0·02] ARB vs 0·13 [SE 0·02] control; absolute difference -0·07 [95% CI -0·12 to -0·01]; p=0·012). Prespecified secondary subgroup analyses showed that the effects of ARB were particularly large in those with pathogenic variants in fibrillin-1, compared with those without such variants (heterogeneity p=0·0050), and there was no evidence to suggest that the effect of ARB varied with β-blocker use (heterogeneity p=0·54). Three trials involving 766 eligible participants compared ARBs with β blockers. During a median follow-up of 3 years, the annual change in the aortic root Z score was similar in the two groups (annual increase -0·08 [SE 0·03] in ARB groups vs -0·11 [SE 0·02] in β-blocker groups; absolute difference 0·03 [95% CI -0·05 to 0·10]; p=0·48). Thus, indirectly, the difference in the annual change in the aortic root Z score between β blockers and control was -0·09 (95% CI -0·18 to 0·00; p=0·042).

INTERPRETATION

In people with Marfan syndrome and no previous aortic surgery, ARBs reduced the rate of increase of the aortic root Z score by about one half, including among those taking a β blocker. The effects of β blockers were similar to those of ARBs. Assuming additivity, combination therapy with both ARBs and β blockers from the time of diagnosis would provide even greater reductions in the rate of aortic enlargement than either treatment alone, which, if maintained over a number of years, would be expected to lead to a delay in the need for aortic surgery.

FUNDING

Marfan Foundation, the Oxford British Heart Foundation Centre for Research Excellence, and the UK Medical Research Council.

Fibrillin-1 Gene Polymorphisms (rs145233125, rs11070646, rs201170905) Are Associated With the Susceptibility and Clinical Prognosis of DeBakey Type III Aortic Dissection in Chinese Han Population

ABSTRACT

We aim to investigate whether genetic variants of the Fibrillin-1 (FBN1) gene were associated with DeBakey type III aortic dissection (AD) and its clinical prognosis in Chinese Han population. Three single-nucleotide polymorphisms (SNPs) (rs145233125, rs11070646, rs201170905) in FBN1 were analyzed in patients with DeBakey type III AD (159) and healthy subjects (216). Gene-environment interactions were evaluated to use generalized multifactor dimensionality reduction. Haplotype analysis of the 3 SNPs in the FBN1 gene was performed by Haploview software. Patients were followed up for average 4 years. G carriers of rs11070646 and rs201170905 in FBN1 have an increased risk of DeBakey type III AD. The interaction of FBN1 and environmental factors facilitated to the increased risk of DeBakey type III AD (cross-validation consistency = 10/10, P = 0.001). One of the most common haplotypes revealed an increased risk of DeBakey type III AD (CGG, P = 0.009). Recessive models of rs145233125 CC genotype ( P < 0.05) and rs201170905 GG genotype ( P < 0.001) were associated with an increased risk of death and recurrent chest pain of DeBakey type III AD. In conclusions, FBN1 gene polymorphisms contribute to DeBakey type III AD susceptibility. The interactions of gene and environment are related with the risk of DeBakey type III AD. C carriers of rs145233125 and G carriers of rs201170905 may be the adverse prognostic indicators of death and recurrent chest pain in DeBakey type III AD.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the use of cardiovascular magnetic resonance in pediatric congenital and acquired heart disease : Endorsed by The American Heart Association

Cardiovascular magnetic resonance (CMR) has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of CMR in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of CMR in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Treatment With Methotrexate Associated With Lipid Core Nanoparticles Prevents Aortic Dilation in a Murine Model of Marfan Syndrome

In Marfan syndrome (MFS), dilation, dissection, and rupture of the aorta occur. Inflammation can be involved in the pathogenicity of aortic defects and can thus be a therapeutic target for MFS. Previously, we showed that the formulation of methotrexate (MTX) associated with lipid nanoparticles (LDE) has potent anti-inflammatory effects without toxicity. To investigate whether LDEMTX treatment can prevent the development of aortic lesions in the MFS murine model. MgΔloxPneo MFS (n = 40) and wild-type (WT, n = 60) mice were allocated to 6 groups weekly injected with IP solutions of: (1) only LDE; (2) commercial MTX; (3) LDEMTX (dose = 1mg/kg) between 3rd and 6th months of life. After 12 weeks of treatments, animals were examined by echocardiography and euthanatized for morphometric and molecular studies. MFS mice treated with LDEMTX showed narrower lumens in the aortic arch, as well as in the ascending and descending aorta. LDEMTX reduced fibrosis and the number of dissections in MFS but not the number of elastic fiber disruptions. In MFS mice, LDEMTX treatment lowered protein expression of pro-inflammatory factors macrophages (CD68), T-lymphocytes (CD3), tumor necrosis factor-α (TNF-α), apoptotic factor cleaved-caspase 3, and type 1 collagen and lowered the protein expression of the transforming growth factor-β (TGF-β), extracellular signal-regulated kinases ½ (ERK1/2), and SMAD3. Protein expression of CD68 and CD3 had a positive correlation with an area of aortic lumen (r² = 0.36; p < 0.001), suggesting the importance of inflammation in the causative mechanisms of aortic dilation. Enhanced adenosine availability by LDEMTX was suggested by higher aortic expression of an anti-adenosine A2a receptor (A2a) and lower adenosine deaminase expression. Commercial MTX had negligible effects. LDEMTX prevented the development of MFS-associated aortic defects and can thus be a candidate for testing in clinical studies.

Exome Sequencing Identifies Genetic Variants Associated with Extreme Manifestations of the Cardiovascular Phenotype in Marfan Syndrome

Marfan Syndrome (MFS) is an autosomal dominant condition caused by variants in the fibrillin-1 (FBN1) gene. Cardinal features of MFS include ectopia lentis (EL), musculoskeletal features and aortic root aneurysm and dissection. Although dissection of the ascending aorta is the main cause of mortality in MFS, the clinical course differs considerably in age of onset and severity, even among individuals who share the same causative variant, suggesting the existence of additional genetic variants that modify the severity of the cardiovascular phenotype in MFS. We recruited MFS patients and classified them into severe (n = 8) or mild aortic phenotype (n = 14) according to age of presentation of the first aorta-related incident. We used Exome Sequencing to identify the genetic variants associated with the severity of aortic manifestations and we performed linkage analysis where suitable. We found five genes associated with severe aortic phenotype and three genes that could be protective for this phenotype in MFS. These genes regulate components of the extracellular matrix, TGFβ pathway and other signaling pathways that are involved in the maintenance of the ECM or angiogenesis. Further studies will be required to understand the functional effect of these variants and explore novel, personalized risk management and, potentially, therapies for these patients.

Society for Cardiovascular Magnetic Resonance/European Society of Cardiovascular Imaging/American Society of Echocardiography/Society for Pediatric Radiology/North American Society for Cardiovascular Imaging Guidelines for the Use of Cardiac Magnetic Resonance in Pediatric Congenital and Acquired Heart Disease: Endorsed by The American Heart Association

Cardiovascular magnetic resonance has been utilized in the management and care of pediatric patients for nearly 40 years. It has evolved to become an invaluable tool in the assessment of the littlest of hearts for diagnosis, pre-interventional management and follow-up care. Although mentioned in a number of consensus and guidelines documents, an up-to-date, large, stand-alone guidance work for the use of cardiovascular magnetic resonance in pediatric congenital 36 and acquired 35 heart disease endorsed by numerous Societies involved in the care of these children is lacking. This guidelines document outlines the use of cardiovascular magnetic resonance in this patient population for a significant number of heart lesions in this age group and although admittedly, is not an exhaustive treatment, it does deal with an expansive list of many common clinical issues encountered in daily practice.

Prevalence of Periodontitis among Patients Diagnosed with Marfan Syndrome: A Cross-Sectional Study Comparing Samples of Healthy Patients

Periodontitis is an inflammatory condition caused by a bacterial plaque and characterized by progressive destruction of the tooth-supporting apparatus. Patients with Marfan syndrome (MFS) exhibit a connective tissue disorder, which can also affect oral soft and hard tissue. Thus, the aims of this cross-sectional study were to assess the association between periodontitis and MFS and secondly, to compare periodontal parameters and prevalence of disease with a control group (CG) without MFS. 152 patients ( $\text{MFS}=76,\text{CG}=76$ ) were recruited to evaluate the following periodontal parameters: probing depth, gingival margin, clinical attachment level, plaque index, and bleeding on probing. The 2017 World Workshop guideline was followed for the diagnosis of the periodontal status. A multivariate analysis was performed using a multinomial logistic regression adjusted for age, gender, and smoking. The level of significance required was $p<0.05$ . Patients with MFS did not show a higher prevalence of periodontitis compared to the CG. However, patients with MFS did have higher values in probing depth, gingival recession, clinical attachment level, and plaque index compared to the CG patients ( $p<0.05$ ). In conclusion, although similar prevalence of periodontitis was found among the studied groups, MFS patients showed worse periodontal parameters.

The role of elastin on the mechanical properties of the anterior leaflet in porcine tricuspid valves

Elastin is present in the extracellular matrix (ECM) of connective tissues, and its mechanical properties are well documented. In Marfan syndrome, however, the inability to properly code for the protein fibrillin-1 prematurely leads to the degradation and loss of elastin fiber integrity in the ECM. In this study, the role of elastin in the ECM of the anterior leaflet of the tricuspid valve was investigated by examining the biomechanical behavior of porcine leaflets before and after the application of the enzyme elastase. Five loading protocols were applied to the leaflet specimens in two groups (elastase-treated and control samples). The mechanical response following elastase application yielded a significantly stiffer material in both the radial and circumferential directions. At a physiological level of stress (85 kPa), the elastase group had an average strain of 26.21% and 6.32% in the radial and circumferential directions, respectively, at baseline prior to elastase application. Following elastase treatment, the average strain was 5.28% and 0.97% in the radial and circumferential directions, respectively. No statistically significant change was found in the control group following sham treatment with phosphate-buffered saline (PBS). Two-photon microscopy images confirmed that after the removal of elastin, the collagen fibers displayed a loss of undulation. With a significant reduction in radial compliance, the ability to withstand physiological loads may be compromised. As such, an extracellular matrix that is structurally deficient in elastin may hinder normal tricuspid valve function.

The fibrillinopathies: new insights with focus on the paradigm of opposing phenotypes for both FBN1 and FBN2

Different pathogenic variants in the fibrillin‐1 gene (FBN1) cause Marfan syndrome and acromelic dysplasias. Whereas the musculoskeletal features of Marfan syndrome involve tall stature, arachnodactyly, joint hypermobility, and muscle hypoplasia, acromelic dysplasia patients present with short stature, brachydactyly, stiff joints, and hypermuscularity. Similarly, pathogenic variants in the fibrillin‐2 gene (FBN2) cause either a Marfanoid congenital contractural arachnodactyly or a FBN2‐related acromelic dysplasia that most prominently presents with brachydactyly. The phenotypic and molecular resemblances between both the FBN1 and FBN2‐related disorders suggest that reciprocal pathomechanistic lessons can be learned. In this review, we provide an updated overview and comparison of the phenotypic and mutational spectra of both the “tall” and “short” fibrillinopathies. The future parallel functional study of both FBN1/2‐related disorders will reveal new insights into how pathogenic fibrillin variants differently affect the fibrillin microfibril network and/or growth factor homeostasis in clinically opposite syndromes. This knowledge may eventually be translated into new therapeutic approaches by targeting or modulating the fibrillin microfibril network and/or the signaling pathways under its control.

Non-Dissecting Distal Aortic and Peripheral Arterial Aneurysms in Patients With Marfan Syndrome

Background

In Marfan syndrome (MFS), an aortic or peripheral arterial dilatation is usually the consequence of aortic dissection. Non-dissecting distal aortic and peripheral aneurysms (DAPA) are barely described. We sought to determine the incidence and prognostic impact of non-dissecting DAPA, requiring a surgical repair in a large population of patients with MFS.

Methods

The patients referred to the French MFS reference center were included in a prospective database, and the patients treated for a non-dissecting DAPA between 2013 and 2020 were retrospectively reviewed. The first-line therapy was open surgery. The patients unfit for open repair or experiencing life-threatening complications underwent endovascular repair.

Results

Among 1,575 patients with MFS, 19 (1.2%) were operated for 25 non-dissecting DAPA. The mean age was 42.4 ± 11.5 years. Non-dissecting DAPA involved the subclavian or axillary artery (n = 12), the descending or thoracoabdominal aorta (n = 6), the abdominal aorta andiliac arteries (n = 6), and the popliteal artery (n = 1). Open and endovascular repairs were performed in 22 and three cases, respectively. After a median follow-up of 54.2 months, no local recurrence was noticed and no secondary procedure was performed. Eight patients presented a new aortic event, including two aortic dissections and seven new aortic surgeries. Compared to the overall MFS population, the non-dissecting DAPA group presented a significantly higher risk of an aortic event (100 vs. 28%, p < 0.0001), a higher risk of aortic dissection (53 vs. 8%, p < 0.0001), and a higher rate of pejorative genetic mutations (68 vs. 40%, p = 0.011).

Conclusion

Among the patients with MFS, the diagnosis of non-dissecting DAPA is infrequent but is associated with a significant adverse outcome, thus, advocating for a specific follow-up.

Thoracoabdominal aortic aneurysm in connective tissue disorder patients

Connective tissue disorders (CTDs) are a group of genetically triggered diseases in which the primary defect involves collagen and elastin protein assembly with potential vascular degenerations such as thoracoabdominal aortic aneurysm (TAAA) and dissection. These most commonly include Marfan syndrome, Ehlers-Danlos syndrome, Loeys-Dietz syndrome, and familial thoracic aortic aneurysm and dissection. Open surgical repair represents the standard approach in this specific group of patients. Extensive aortic replacements are generally performed in order to reduce long-term complications caused by the progressive dilatation of the remnant aortic segments. In the last decades, endovascular interventions have emerged as a valid alternative in patients affected by degenerative TAAA. However, in patients with CTD, this approach presents higher rates of reinterventions and postoperative complications with a disputable long-term durability, and it is nowadays performed for very selective indications such as severe comorbidities and urgent/emergent settings. Despite a deeper knowledge of the pathophysiological mechanisms involved in CTD, improvements in medical therapy, and a multidisciplinary approach fully involved in the management of these usually frailer patients, this specific group still represents a challenge. Further dedicated studies addressing mid-term and long-term outcomes in this selected population are needed.

Marfan Syndrome with Aortic Root Disease, Severe Heart Failure and Aortic Dissection- Two Case Reports

Marfan syndrome is an uncommon inheritable connective tissue disease which affects the cardiovascular system. This paper presents two cases of Marfan Syndrome with predominant aortic root disease that were seen at the Cardiology Clinic of University of Nigeria Teaching Hospital, Enugu, Nigeria. Their biography, clinical features and echocardiography parameters were captured using structured questionnaire. Both were young males in their 4^th decade of life, and had advanced aortic root diseases which were complicated by left ventricular failure in both, while one of them had aortic dissection and ischemic stroke. Young adult Nigerians with Marfan syndrome presented with advanced aortic root diseases, heart failure, aortic dissection and stroke.

A Case Report of Marfan Syndrome Presenting With Atypical Chest Pain: A 28-Year-Old Male With Non-ST-Elevation Myocardial Infarction (NSTEMI)

Marfan syndrome is a rare autosomal dominant disorder of the connective tissue. It results in a mutation in the Fibrillin-1 protein gene. We present a case of  Marfan’s syndrome in a young adult with life-threatening, sudden onset of chest pain secondary to a non-ST elevation myocardial infarction (NSTEMI) in the setting of an aortic pseudoaneurysm. Taking into consideration potential life-threatening underlying processes, a thorough and detailed methodology must be undertaken when encountering chest pain in a Marfan’s syndrome patient. This case highlights the importance of utilizing a multi-disciplinary approach to the complexities of Marfan syndrome.

An update of medical care in Marfan syndrome

Marfan syndrome (MFS), a multisystemic connective disorder, caused by fibrillin 1 gene mutations with autosomal dominant inheritance. The disease spectrum is wide and the major causes of death are related to aortic root aneurysm or dissection. The purposes of medical treatment are to reduce structural changes in the aortic wall and slow aortic root dilatation. Advance in medical researches have provided new insights into the pathogenesis of disease and opened up new horizons for treatments. Several medications such as angiotensin II type I receptor blockers, β-blockers, angiotensin-converting enzyme inhibitors, calcium channel blockers, tetracyclines, and statins have been studied for the purpose. Currently, the life expectancy of Marfan patients improves significantly and is closes to the general population with proper treatment. In this article, we review and update the medical treatments for patients with MFS.

Pathophysiology and Pathogenesis of Marfan Syndrome

Marfan syndrome (MFS) is a systemic connective tissue disorder that is inherited in an autosomal dominant pattern with variable penetrance. While clinically this disease manifests in many different ways, the most life-threatening manifestations are related to cardiovascular complications including mitral valve prolapse, aortic insufficiency, dilatation of the aortic root, and aortic dissection. In the past 30 years, research efforts have not only identified the genetic locus responsible but have begun to elucidate the molecular pathogenesis underlying this disorder, allowing for the development of seemingly rational therapeutic strategies for treating affected individuals. In spite of these advancements, the cardiovascular complications still remain as the most life-threatening clinical manifestations. The present chapter will focus on the pathophysiology and clinical treatment of Marfan syndrome, providing an updated overview of the recent advancements in molecular genetics research and clinical trials, with an emphasis on how this information can focus future efforts toward finding betters ways to detect, diagnose, and treat this devastating condition.

The NO signalling pathway in aortic aneurysm and dissection

Recent studies have shown that NO is a central mediator in diseases associated with thoracic aortic aneurysm, such as Marfan syndrome. The progressive dilation of the aorta in thoracic aortic aneurysm ultimately leads to aortic dissection. Unfortunately, current medical treatments have neither halt aortic enlargement nor prevented rupture, leaving surgical repair as the only effective treatment. There is therefore a pressing need for effective therapies to delay or even avoid the need for surgical repair in thoracic aortic aneurysm patients. Here, we summarize the mechanisms through which NO signalling dysregulation causes thoracic aortic aneurysm, particularly in Marfan syndrome. We discuss recent advances based on the identification of new Marfan syndrome mediators related to pathway overactivation that represent potential disease biomarkers. Likewise, we propose iNOS, sGC and PRKG1, whose pharmacological inhibition reverses aortopathy in Marfan syndrome mice, as targets for therapeutic intervention in thoracic aortic aneurysm and are candidates for clinical trials.

Oxidative Stress-Related Susceptibility to Aneurysm in Marfan's Syndrome

The involvement of highly reactive oxygen-derived free radicals (ROS) in the genesis and progression of various cardiovascular diseases, including arrhythmias, aortic dilatation, aortic dissection, left ventricular hypertrophy, coronary arterial disease and congestive heart failure, is well-established. It has also been suggested that ROS may play a role in aortic aneurysm formation in patients with Marfan's syndrome (MFS). This syndrome is a multisystem disorder with manifestations including cardiovascular, skeletal, pulmonary and ocular systems, however, aortic aneurysm and dissection are still the most life-threatening manifestations of MFS. In this review, we will concentrate on the impact of oxidative stress on aneurysm formation in patients with MFS as well as on possible beneficial effects of some agents with antioxidant properties. Mechanisms responsible for oxidative stress in the MFS model involve a decreased expression of superoxide dismutase (SOD) as well as enhanced expression of NAD(P)H oxidase, inducible nitric oxide synthase (iNOS) and xanthine oxidase. The results of studies have indicated that reactive oxygen species may be involved in smooth muscle cell phenotype switching and apoptosis as well as matrix metalloproteinase activation, resulting in extracellular matrix (ECM) remodeling. The progression of the thoracic aortic aneurysm was suggested to be associated with markedly impaired aortic contractile function and decreased nitric oxide-mediated endothelial-dependent relaxation.

Aortic events in pregnant patients with Marfan syndrome. Lessons from a multicenter study

INTRODUCTION AND OBJECTIVES

Pregnancy in women with Marfan syndrome (MS) is associated with an increased risk of aortic events. The clinical evidence on pregnant patients with MS is limited and there is no specific consensus on their optimal management. We report our multicenter experience.

METHODS

From January 2004 to January 2020, 632 patients with MS underwent periodic monitoring in Marfan units. During this period, we identified all pregnant women with MS and analyzed the incidence of aortic events during pregnancy and puerperium.

RESULTS

There were 133 pregnancies in 89 women with MS (8 women with prior aortic surgery). There were no maternal deaths, but 5 women had aortic events during the third trimester and puerperium (type A dissections in 2, type B dissection in 1, and significant [≥ 3mm] aortic growth in 2). The aortic event rate was 3.7%. Pregestational aortic diameter≥ 40mm showed a nonsignificant association with aortic events (P=.058). Fetal mortality was 3% and 37.6% of births were cesarean deliveries.

CONCLUSIONS

Women with MS have an increased risk of aortic events during pregnancy, especially in the third trimester and postpartum period. Patients with MS and aortic diameters ≥40mm should be assessed in experienced centers for prophylactic aortic surgery before pregnancy. It is important to provide early diagnosis, prepregnancy study of the aorta, beta-blocker administration, and close monitoring during pregnancy, especially during the last trimester and postpartum.

An Overview of Investigational and Experimental Drug Treatment Strategies for Marfan Syndrome

Marfan syndrome (MFS) is a heritable connective tissue disorder caused by pathogenic variants in the gene coding for the extracellular matrix protein fibrillin-1. While the disease affects multiple organ systems, the most life-threatening manifestations are aortic aneurysms leading to dissection and rupture. Other cardiovascular complications, including mitral valve prolapse, primary cardiomyopathy, and arrhythmia, also occur more frequently in patients with MFS. The standard medical care relies on cardiovascular imaging at regular intervals, along with pharmacological treatment with β-adrenergic receptor blockers aimed at reducing the aortic growth rate. When aortic dilatation reaches a threshold associated with increased risk of dissection, prophylactic surgical aortic replacement is performed. Although current clinical management has significantly improved the life expectancy of patients with MFS, no cure is available and fatal complications still occur, underscoring the need for new treatment options. In recent years, preclinical studies have identified a number of potentially promising therapeutic targets. Nevertheless, the translation of these results into clinical practice has remained challenging. In this review, we present an overview of the currently available knowledge regarding the underlying pathophysiological processes associated with MFS cardiovascular pathology. We then summarize the treatment options that have been developed based on this knowledge and are currently in different stages of preclinical or clinical development, provide a critical review of the limitations of current studies and highlight potential opportunities for future research.

Affected-embryo-based SNP haplotyping with NGS for the preimplantation genetic testing of Marfan syndrome

Marfan syndrome (MFS), an autosomal dominant heritable disease of the connective tissue, is characterized by broad clinical manifestations in the musculoskeletal, cardiovascular, pulmonary, and ocular systems. In this study, a male patient with MFS caused by a heterozygous mutation NM_000138.5(FBN1):c.6037 + 2 T > C in the fibrillin 1 gene (FBN1) underwent preimplantation genetic testing (PGT) by using affected-embryo-based single nucleotide polymorphism (SNP) haplotyping. Multiple displacement amplification was used for whole genome amplification of biopsied trophectoderm cells after controlled ovarian stimulation. Sanger sequencing and next-generation sequencing (NGS) were used to detect the state of FBN1 mutation. A total of 14 blastocysts formed after intracytoplasmic sperm injection were biopsied. After NGS, 60 informative polymorphic SNP markers located upstream and downstream of the FBN1 gene and its pathogenic mutation site were linked to individual alleles. Sanger sequencing further confirmed that 8 blastocysts carried the mutation NM_000138.5(FBN1):c.6037 + 2 T > C, while 6 did not. Four of the non-carriers were euploid verified by copy number variation results. A female infant without MFS was born at 37 weeks gestation after a subsequent frozen embryo transfer. In conclusion, the successful case indicates that SNP haplotyping using sibling embryos as a reference is applicable to PGT in monogenetic diseases.Abbreviations MFS: Marfan syndrome; PGT: preimplantation genetic testing; FBN1: fibrillin 1 gene; NGS: next-generation sequencing; SNP: single nucleotide polymorphism.

Generation of a human iPSC line QDMHi001-A from a patient with Marfan syndrome carrying a heterozygous c.6772 T > C variant in FBN1

Variants in FBN1 are associated with Marfan Syndrome, an autosomal dominant disorder with clinical features that involve the musculoskeletal, cardiovascular and ocular systems. We generated a human iPSC line QDMHi001-A from a patient with Marfan syndrome and a heterozygous c.6772 T > C (p.Cys2258Arg) variant in FBN1. This line will be a valuable resource for in vitro disease modeling and drug testing for Marfan syndrome.

Mutation spectrum and genotype-phenotype correlations in Chinese congenital ectopia lentis patients

PURPOSE

To identify the spectrum and frequency of mutations in congenital ectopia lentis (CEL) and to investigate the correlations between genotype and clinical phenotype in Chinese CEL patients.

METHODS

Ninety-three participants with CEL were enrolled from March 2017 to April 2020. Ocular and systemic examinations were performed for each included patient. Genomic DNA from the included patients was analysed by whole-exome sequencing to detect mutations. Clinical manifestations were compared for different mutation subgroups.

RESULTS

Gene mutations were detected in 79 patients. Sixty-five were FBN1-associated, and most were related to Marfan syndrome (MFS). The FBN1 mutations mainly consisted of missense mutations (49/65) and were concentrated in the 5' region. Probands with missense mutations tend to show high corneal astigmatism (χ² = 3.98, P = 0.046) and severe lens dislocation (t = 2.90, P = 0.006) compared to premature termination codon (PTC) mutations.

CONCLUSIONS

Most Chinese CEL patients were identified as having FBN1 mutations. Those with missense mutations commonly showed severe ocular phenotypes; therefore, reinforced follow-up and long-term observation are required. These correlations implicated the crucial role of missense and cysteine-involving mutations in ocular phenotypes, which might be explained by dominant-negative and nonsense-mediated mRNA decay (NMD).

Extracellular Tuning of Mitochondrial Respiration Leads to Aortic Aneurysm

Supplemental Digital Content is available in the text.

Background:

Marfan syndrome (MFS) is an autosomal dominant disorder of the connective tissue caused by mutations in the FBN1 (fibrillin-1) gene encoding a large glycoprotein in the extracellular matrix called fibrillin-1. The major complication of this connective disorder is the risk to develop thoracic aortic aneurysm. To date, no effective pharmacologic therapies have been identified for the management of thoracic aortic disease and the only options capable of preventing aneurysm rupture are endovascular repair or open surgery. Here, we have studied the role of mitochondrial dysfunction in the progression of thoracic aortic aneurysm and mitochondrial boosting strategies as a potential treatment to managing aortic aneurysms.

Methods:

Combining transcriptomics and metabolic analysis of aortas from an MFS mouse model (Fbn1^c1039g/+) and MFS patients, we have identified mitochondrial dysfunction alongside with mtDNA depletion as a new hallmark of aortic aneurysm disease in MFS. To demonstrate the importance of mitochondrial decline in the development of aneurysms, we generated a conditional mouse model with mitochondrial dysfunction specifically in vascular smooth muscle cells (VSMC) by conditional depleting Tfam (mitochondrial transcription factor A; Myh11-Cre^ERT2Tfam^flox/flox mice). We used a mouse model of MFS to test for drugs that can revert aortic disease by enhancing Tfam levels and mitochondrial respiration.

Results:

The main canonical pathways highlighted in the transcriptomic analysis in aortas from Fbn1^c1039g/+ mice were those related to metabolic function, such as mitochondrial dysfunction. Mitochondrial complexes, whose transcription depends on Tfam and mitochondrial DNA content, were reduced in aortas from young Fbn1^c1039g/+ mice. In vitro experiments in Fbn1-silenced VSMCs presented increased lactate production and decreased oxygen consumption. Similar results were found in MFS patients. VSMCs seeded in matrices produced by Fbn1-deficient VSMCs undergo mitochondrial dysfunction. Conditional Tfam-deficient VSMC mice lose their contractile capacity, showed aortic aneurysms, and died prematurely. Restoring mitochondrial metabolism with the NAD precursor nicotinamide riboside rapidly reverses aortic aneurysm in Fbn1^c1039g/+ mice.

Conclusions:

Mitochondrial function of VSMCs is controlled by the extracellular matrix and drives the development of aortic aneurysm in Marfan syndrome. Targeting vascular metabolism is a new available therapeutic strategy for managing aortic aneurysms associated with genetic disorders.

AAV-mediated AP-1 decoy oligonucleotide expression inhibits aortic elastolysis in a mouse model of marfan syndrome

AIMS

Marfan syndrome is one of the most common inherited disorders of connective tissue caused by fibrillin-1 mutations, characterized by enhanced transcription factor AP-1 DNA binding activity and subsequently abnormally increased expression and activity of matrix-metalloproteinases (MMPs). We aimed to establish a novel adeno-associated virus (AAV)-based strategy for long-term expression of an AP-1 neutralising RNA hairpin (hp) decoy oligonucleotide (dON) in the aorta to prevent aortic elastolysis in a murine model of Marfan syndrome.

METHODS AND RESULTS

Using fibrillin-1 hypomorphic mice (mgR/mgR), aortic grafts from young (9 weeks old) donor mgR/mgR mice were transduced ex vivo with AAV vectors and implanted as infrarenal aortic interposition grafts in mgR/mgR mice. Grafts were explanted after 30 days. For in vitro studies isolated primary aortic smooth muscle cells from mgR/mgR mice were used. Elastica-van-Giesson staining visualized elastolysis, ROS production was assessed using DHE staining. RNA F.I.S.H. verified AP-1 hp dON generation in the ex vivo transduced aortic tissue. MMP expression and activity were assessed by western blotting and immunoprecipitation combined with zymography.Transduction resulted in stable therapeutic dON expression in endothelial and smooth muscle cells. MMP expression and activity, ROS formation as well as expression of monocyte chemoattractant protein-1 were significantly reduced. Monocyte graft infiltration declined and the integrity of the elastin architecture was maintained. RNAseq analyzis confirmed the beneficial effect of AP-1 neutralisation on the pro-inflammatory environment in smooth muscle cells.

CONCLUSIONS

This novel approach protects from deterioration of aortic stability by sustained delivery of nucleic acids-based therapeutics and further elucidated how to interfere with the mechanism of elastolysis.

TRANSLATIONAL PERSPECTIVE

This study provides a novel single treatment option to achieve long-term expression of a transcription factor AP-1 neutralising decoy oligonucleotide in the aorta of mgR/mgR mice with the potential to prevent life-threatening elastolysis and aortic complications.

Genotype FBN1/phenotype relationship in a cohort of patients with Marfan syndrome

Marfan syndrome (MFS) is a systemic connective tissue disorder caused by mutations in the fibrillin-1 (FBN1) gene, and cardiovascular involvement is the leading cause of mortality. We sought to examine the genotype/phenotype realtionship in 61 consecutive patients with a phenotype and genotype compatible with MFS. The FBN1 gene was analyzed by massive sequencing using a hybridization capture-based target enrichment custom panel. Forty-three different variants of FBN1 were identified, of which 17 have not been previously reported. The causal variants of MFS were grouped into mutations resulting in haploinsufficiency (HI group; 23 patients) and mutations producing a dominant-negative effect (DN group; 38 patients). Patient information was collected from electronic medical records and clinical evaluation. While no significant differences were found between the two groups, the HI group included more cases with aortic dissection and occurring at a younger age that the DN group (34.7% vs. 15.8%; p = 0.160). Irrespective of the mutation group, males presented with a higher probability of aortic involvement (4-fold higher risk than females) and aortic dissections events occurred at younger ages. Patients with DN variants carrying a cysteine substitution had a higher incidence of ectopia lentis.

Management of a giant aortic root aneurysm in a young patient with Marfan syndrome: a case report

Introduction

Marfan syndrome (MFS) is a common heritable connective tissue disease involving multiple organs. Even though the clinical manifestations of MFS can be various, aortic root aneurysm is estimated as one of the most serious complications. We herein describe an individualized treatment decision-making process for a 23-year-old male with MFS, suffering from a giant but stable aortic root aneurysm which is extremely rare at his age.

Case

The patient, a 23-year-old male with a family history of MFS, presented to our cardiovascular department because of progressive exertional chest distress, fatigue and occasional precordial pain. Physical examinations revealed 190.5 cm of height, high myopia, and a diastolic murmur at the aortic valve area. Laboratory examinations for systemic vasculitis and infectious diseases were negative. Transthoracic echocardiography and enhanced thoracic computed tomography (CT) scan revealed the existence of a giant aortic root aneurysm (125.1 mm in short-axis), severe aortic valve regurgitation, cardiac dilatation (LV; 99 mm in diastolic diameter) and a poor ejection fraction (EF; 18%). Considering the risk of rupture or dissection of the dilated aortic root, we performed Bentall procedure based on the results of multidisciplinary team discussion and intraoperative exploration. Postoperative thoracic CT scan revealed a normal sized reconstructed aortic root, and the patient was discharged uneventfully 7 days later.

Conclusion

It is extremely rare to report such a giant aortic root aneurysm in a young patient. In the treatment decision-making process, the patient’s specific situation should be taken into consideration. A mechanical Bentall procedure seems to be an acceptable option for some selected cases.

Specific miRNA and Gene Deregulation Characterize the Increased Angiogenic Remodeling of Thoracic Aneurysmatic Aortopathy in Marfan Syndrome

Marfan syndrome (MFS) is a connective tissue disease caused by mutations in the FBN1 gene, leading to alterations in the extracellular matrix microfibril assembly and the early formation of thoracic aorta aneurysms (TAAs). Non-genetic TAAs share many clinico-pathological aspects with MFS and deregulation of some microRNAs (miRNAs) has been demonstrated to be involved in the progression of TAA. In this study, 40 patients undergoing elective ascending aorta surgery were enrolled to compare TAA histomorphological features, miRNA profile and related target genes in order to find specific alterations that may explain the earlier and more severe clinical outcomes in MFS patients. Histomorphological, ultrastructural and in vitro studies were performed in order to compare aortic wall features of MFS and non-MFS TAA. MFS displayed greater glycosaminoglycan accumulation and loss/fragmentation of elastic fibers compared to non-MFS TAA. Immunohistochemistry revealed increased CD133⁺ angiogenic remodeling, greater MMP-2 expression, inflammation and smooth muscle cell (SMC) turnover in MFS TAA. Cultured SMCs from MFS confirmed higher turnover and α-smooth muscle actin expression compared with non-MFS TAA. Moreover, twenty-five miRNAs, including miR-26a, miR-29, miR-143 and miR-145, were found to be downregulated and only miR-632 was upregulated in MFS TAA in vivo. Bioinformatics analysis revealed that some deregulated miRNAs in MFS TAA are implicated in cell proliferation, extracellular matrix structure/function and TGFβ signaling. Finally, gene analysis showed 28 upregulated and seven downregulated genes in MFS TAA, some of them belonging to the CDH1/APC and CCNA2/TP53 signaling pathways. Specific miRNA and gene deregulation characterized the aortopathy of MFS and this was associated with increased angiogenic remodeling, likely favoring the early and more severe clinical outcomes, compared to non-MFS TAA. Our findings provide new insights concerning the pathogenetic mechanisms of MFS TAA; further investigation is needed to confirm if these newly identified specific deregulated miRNAs may represent potential therapeutic targets to counteract the rapid progression of MFS aortopathy.

A synonymous mutation in exon 39 of FBN1 causes exon skipping leading to Marfan syndrome

Marfan syndrome is a heritable autosomal-dominant connective tissue disorder and it was typically caused by mutations in FBN1. However, the synonymous mutation was seldom recorded to be related to Marfan syndrome. Hereon, Multiplex ligation-dependent probe amplification failed to detect a copy number variant involving FBN1 but a synonymous mutation c.4773A > G (p.Gly1591Gly) was identified by NGS in exon 39. RNA was extracted from patient's aortic tissue and reverse polymerase chain reaction demonstrated the presence of a shortened mRNA transcript. Results of minigene models indicated that c.4773A > G was bona fide responsibility for the aberrant splicing pattern, and artificial mutations of c.4773A > C and c.4773A > T also gave rise to fragments with exon 39 entire skipped. Together, the novel synonymous mutations in c.4773 position (A > G, C, T), middle of exon 39 of FBN1 gene, was found to be associated with Marfan syndrome by altering the splicing pattern of pre-mRNA.

Marfan syndrome revisited: From genetics to the clinic

Marfan syndrome is an autosomal dominant connective tissue disease with an estimated incidence of 1 in 5000 individuals. In 90% of cases it is caused by mutations in the gene for fibrillin-1, the main constituent of extracellular microfibrils. Studies on animal models of Marfan syndrome have revealed that fibrillin-1 mutations interfere with local TGF-β signaling, in addition to impairing tissue integrity. The cardinal features involve the cardiovascular, ocular and skeletal systems. The diagnosis of Marfan syndrome is made according to the revised Ghent nosology. Early identification and appropriate management are critical for patients with Marfan syndrome, who are prone to the life-threatening cardiovascular complications of aortic aneurysms and aortic dissection. The standard treatment includes prophylactic beta-blockers in order to slow down dilation of the ascending aorta, and prophylactic aortic surgery. The success of current medical and surgical treatment of aortic disease in Marfan syndrome has substantially improved mean life expectancy, extending it above 72 years. This review aims to provide an overview of this hereditary disorder.