Coding and Non-Coding Transcriptomic Landscape of Aortic Complications in Marfan Syndrome.

Marfan syndrome (MFS) is a rare congenital disorder of the connective tissue, leading to thoracic aortic aneurysms (TAA) and dissection, among other complications. Currently, the most efficient strategy to prevent life-threatening dissection is preventive surgery. Periodic imaging applying complex techniques is required to monitor TAA progression and to guide the timing of surgical intervention. Thus, there is an acute demand for non-invasive biomarkers for diagnosis and prognosis, as well as for innovative therapeutic targets of MFS. Unraveling the intricate pathomolecular mechanisms underlying the syndrome is vital to address these needs. High-throughput platforms are particularly well-suited for this purpose, as they enable the integration of different datasets, such as transcriptomic and epigenetic profiles. In this narrative review, we summarize relevant studies investigating changes in both the coding and non-coding transcriptome and epigenome in MFS-induced TAA. The collective findings highlight the implicated pathways, such as TGF-ß signaling, extracellular matrix structure, inflammation, and mitochondrial dysfunction. Potential candidates as biomarkers, such as miR-200c, as well as therapeutic targets emerged, like Tfam, associated with mitochondrial respiration, or miR-632, stimulating endothelial-to-mesenchymal transition. While these discoveries are promising, rigorous and extensive validation in large patient cohorts is indispensable to confirm their clinical relevance and therapeutic potential.

Targeted next-generation sequencing reveals the genetic mechanism of Chinese Marfan syndrome cohort with ocular manifestation.

BACKGROUND: Marfan syndrome (MFS) is a hereditary connective tissue disorder involving multiple systems, including ophthalmologic abnormalities. Most cases are due to heterozygous mutations in the fibrillin-1 gene (FBN1). Other associated genes include LTBP2, MYH11, MYLK, and SLC2A10. There is significant clinical overlap between MFS and other Marfan-like disorders. PURPOSE: To expand the mutation spectrum of FBN1 gene and validate the pathogenicity of Marfan-related genes in patients with MFS and ocular manifestations. METHODS: We recruited 318 participants (195 cases, 123 controls), including 59 sporadic cases and 88 families. All patients had comprehensive ophthalmic examinations showing ocular features of MFS and met Ghent criteria. Additionally, 754 cases with other eye diseases were recruited. Panel-based next-generation sequencing (NGS) screened mutations in 792 genes related to inherited eye diseases. RESULTS: We detected 181 mutations with an 84.7% detection rate in sporadic cases and 87.5% in familial cases. The overall detection rate was 86.4%, with FBN1 accounting for 74.8%. In cases without FBN1 mutations, 23 mutations from seven Marfan-related genes were identified, including four pathogenic or likely pathogenic mutations in LTBP2. The 181 mutations included 165 missenses, 10 splicings, three frameshifts, and three nonsenses. FBN1 accounted for 53.0% of mutations. The most prevalent pathogenic mutation was FBN1 c.4096G>A. Additionally, 94 novel mutations were detected, with 13 de novo mutations in 14 families. CONCLUSION: We expanded the mutation spectrum of the FBN1 gene and provided evidence for the pathogenicity of other Marfan-related genes. Variants in LTBP2 may contribute to the ocular manifestations in MFS, underscoring its role in phenotypic diversity.

[Correlation of posterior segment lesions with anterior segment biometric parameters and FBN1 genotype in patients with Marfan syndrome].

Objective: To investigate the characteristics of posterior segment lesions in Marfan syndrome (MFS) patients and their relationship with anterior segment biometric parameters and FBN1 genotype. Methods: A cross-sectional study was conducted. A total of 121 MFS patients, 76 males and 45 females, with an average age of (11.72±11.66) years, who visited the Department of Ophthalmology, Eye & ENT Hospital of Fudan University from January 2013 to March 2023 were included. The presence of posterior scleral staphyloma was observed using B-mode ultrasound, and macular lesions were identified and classified using the atrophy-traction-neovascularization system based on ultra-widefield fundus images, color fundus images, and optical coherence tomography scans. Anterior segment biometric parameters, including axial length of the eye, average corneal curvature, corneal astigmatism, horizontal corneal diameter, anterior chamber depth, and lens thickness, were collected, and the direction and extent of lens dislocation were observed. Molecular genetic analysis of FBN1 gene mutations in patients was performed using next-generation sequencing based on a panel of ocular genetic diseases, and the impact of the genotype and anterior segment biometric parameters on the posterior segment manifestations was analyzed. Results: Sixty patients exhibited posterior segment lesions, including retinal detachment (4 cases, 3.31%), macular lesions (47 cases, 38.84%), and posterior scleral staphyloma (54 cases, 44.63%). There was statistically significant difference in axial length of the eye between patients with and without posterior scleral staphyloma [23.09 (22.24, 24.43) and 27.04 (25.44, 28.88) mm], between patients with and without macular lesions [23.16 (22.24, 24.61) and 27.04 (25.74, 28.78) mm], and between patients with and without atrophic macular lesions [23.16 (22.24, 24.61) and 27.04 (25.74, 28.79) mm] (all P<0.001). There was statistically significant difference in anterior chamber depth between patients with and without macular lesions [3.11 (2.75, 3.30) and 3.34 (3.09, 3.60) mm] (P<0.05). There was also statistically significant difference in corneal astigmatism between patients with and without posterior scleral staphyloma [2.15 (1.20, 2.93) and 1.40 (1.00, 2.20) diopters] (P<0.05). The location and region of the FBN1 gene mutation not only showed statistically significant difference from the positive rates of posterior scleral staphyloma and macular lesions (all P<0.05), but also influenced the occurrence of atrophic macular lesions (both P<0.05). Patients with FBN1 mutations located in the transforming growth factor ß regulatory sequence had the highest proportion of posterior scleral staphyloma and macular lesions (both 10/11). Conclusions: Posterior scleral staphyloma and macular lesions have a relatively high incidence in MFS patients and tend to progress to more severe grades. The age, axial length of the eye, anterior chamber depth, corneal astigmatism, and location and region of the FBN1 gene mutation are factors affecting the posterior segment lesions in MFS patients.

Generation of an induced pluripotent stem cell line, JHUi005-A, from a Marfan Syndrome patient harboring a pathogenic c.3338-2A>C intronic splicing variant.

Marfan Syndrome, a connective tissue disorder caused by Fibrillin-1 (FBN1) gene mutations, induces disease in the ocular, musculoskeletal, and cardiovascular systems and increases aortic vulnerability to rupture associated with high mortality rates. We describe an induced pluripotent stem cell line (HFD1) generated from patient-derived human dermal fibroblasts harboring a heterozygous c.3338-2A>C intronic splice acceptor site variant preceding Exon 28 of FBN1. The clonal line, which produces abnormal FBN1 splice variants, has a normal karyotype, expresses appropriate stemness markers, and maintains trilineage differentiation potential. This line represents a valuable resource for studying how abnormal splicing variants contribute to Marfan Syndrome.

High-Throughput Genomics Identify Novel FBN1/2 Variants in Severe Neonatal Marfan Syndrome and Congenital Heart Defects.

Fibrillin-1 and fibrillin-2, encoded by FBN1 and FBN2, respectively, play significant roles in elastic fiber assembly, with pathogenic variants causing a diverse group of connective tissue disorders such as Marfan syndrome (MFS) and congenital contractural arachnodactyly (CCD). Different genomic variations may lead to heterogeneous phenotypic features and functional consequences. Recent high-throughput sequencing modalities have allowed detection of novel variants that may guide the care for patients and inform the genetic counseling for their families. We performed clinical phenotyping for two newborn infants with complex congenital heart defects. For genetic investigations, we employed next-generation sequencing strategies including whole-genome Single-Nucleotide Polymorphism (SNP) microarray for infant A with valvular insufficiency, aortic sinus dilatation, hydronephrosis, and dysmorphic features, and Trio whole-exome sequencing (WES) for infant B with dextro-transposition of the great arteries (D-TGA) and both parents. Infant A is a term male with neonatal marfanoid features, left-sided hydronephrosis, and complex congenital heart defects including tricuspid regurgitation, aortic sinus dilatation, patent foramen ovale, patent ductus arteriosus, mitral regurgitation, tricuspid regurgitation, aortic regurgitation, and pulmonary sinus dilatation. He developed severe persistent pulmonary hypertension and worsening acute hypercapnic hypoxemic respiratory failure, and subsequently expired on day of life (DOL) 10 after compassionate extubation. Cytogenomic whole-genome SNP microarray analysis revealed a deletion within the FBN1 gene spanning exons 7-30, which overlapped with the exon deletion hotspot region associated with neonatal Marfan syndrome. Infant B is a term male prenatally diagnosed with isolated D-TGA. He required balloon atrial septostomy on DOL 0 and subsequent atrial switch operation, atrial septal defect repair, and patent ductus arteriosus ligation on DOL 5. Trio-WES revealed compound heterozygous c.518C>T and c.8230T>G variants in the FBN2 gene. Zygosity analysis confirmed each of the variants was inherited from one of the parents who were healthy heterozygous carriers. Since his cardiac repair at birth, he has been growing and developing well without any further hospitalization. Our study highlights novel FBN1/FBN2 variants and signifies the phenotype-genotype association in two infants affected with complex congenital heart defects with and without dysmorphic features. These findings speak to the importance of next-generation high-throughput genomics for novel variant detection and the phenotypic variability associated with FBN1/FBN2 variants, particularly in the neonatal period, which may significantly impact clinical care and family counseling.

Multidisciplinary follow-up in a patient with Morgagni hernia leads to diagnosis of Marfan syndrome.

BACKGROUND: congenital diaphragmatic hernia (CDH) is a birth defect occurring in isolated or syndromic (chromosomal or monogenic) conditions. The diaphragmatic defect can be the most common one: left-sided posterolateral, named Bochdalek hernia; or it can be an anterior-retrosternal defect, named Morgagni hernia. Marfan syndrome (MFS) is a rare autosomal dominant inherited condition that affects connective tissue, caused by mutations in fibrillin-1 gene on chromosome 15. To date various types of diaphragmatic defects (about 30 types) have been reported in association with MFS, but they are heterogeneous, including CDH and paraesophageal hernia. CASE PRESENTATION: We describe the case of a child incidentally diagnosed with Morgagni hernia through a chest X-ray performed due to recurrent respiratory tract infections. Since the diagnosis of CDH, the patient underwent a clinical multidisciplinary follow-up leading to the diagnosis of MFS in accordance with revised Ghent Criteria: the child had typical clinical features and a novel heterozygous de novo single-base deletion in exon 26 of the FBN1 gene, identified by Whole-Exome Sequencing. MFS diagnosis permitted to look for cardiovascular complications and treat them, though asymptomatic, in order to prevent major cardiovascular life-threatening events. CONCLUSION: Our case shows the importance of a long-term and multidisciplinary follow-up in all children with diagnosis of CDH.

Causative role of a novel intronic indel variant in FBN1 and maternal germinal mosaicism in Marfan syndrome.

BACKGROUND: Marfan syndrome (MFS) is an autosomal dominant connective tissue disease with wide clinical heterogeneity, and mainly caused by pathogenic variants in fibrillin-1 (FBN1). METHODS: A Chinese 4-generation MFS pedigree with 16 family members was recruited and exome sequencing (ES) was performed in the proband. Transcript analysis (patient RNA and minigene assays) and in silico structural analysis were used to determine the pathogenicity of the variant. In addition, germline mosaicism in family member (Ι:1) was assessed using quantitative fluorescent polymerase chain reaction (QF-PCR) and short tandem repeat PCR (STR) analyses. RESULTS: Two cis-compound benign intronic variants of FBN1 (c.3464-4 A > G and c.3464-5G > A) were identified in the proband by ES. As a compound variant, c.3464-5_3464-4delGAinsAG was found to be pathogenic and co-segregated with MFS. RNA studies indicated that aberrant transcripts were found only in patients and mutant-type clones. The variant c.3464-5_3464-4delGAinsAG caused erroneous integration of a 3 bp sequence into intron 28 and resulted in the insertion of one amino acid in the protein sequence (p.Ile1154_Asp1155insAla). Structural analyses suggested that p.Ile1154_Asp1155insAla affected the protein's secondary structure by interfering with one disulfide bond between Cys1140 and Cys1153 and causing the extension of an anti-parallel ß sheet in the calcium-binding epidermal growth factor-like (cbEGF)13 domain. In addition, the asymptomatic family member Ι:1 was deduced to be a gonadal mosaic as assessed by inconsistent results of sequencing and STR analysis. CONCLUSIONS: To our knowledge, FBN1 c.3464-5_3464-4delGAinsAG is the first identified pathogenic intronic indel variant affecting non-canonical splice sites in this gene. Our study reinforces the importance of assessing the pathogenic role of intronic variants at the mRNA level, with structural analysis, and the occurrence of mosaicism.

Genotype and clinical phenotype of children with Marfan syndrome in Southeastern Anatolia.

The cardinal phenotypic hallmarks of Marfan syndrome (MFS) include cardiac, ocular, and skeletal abnormalities. Since the clinical phenotype of MFS is highly heterogeneous, with certain symptoms appearing as children age, the diagnostic process and establishing a genotype-phenotype association in childhood MFS can be challenging. The lack of sufficient childhood studies also makes it difficult to interpret the subject. This study aims to evaluate the relationship between clinical symptoms used as diagnostic criteria and FBN1 variations in children with MFS. This study investigated the relationships between genotypes and phenotypes in 131 children suspected of having Marfan syndrome (MFS). Diagnosis of MFS was made according to the revised Ghent nosology. FBN1 variants were categorized based on exon regions, type of variant, and pathogenicity classes. These FBN1 variants were then correlated with the clinical manifestations including cardiovascular, ocular, facial, and skeletal abnormalities. Out of the children, 43 were diagnosed with MFS. FBN1 variant was identified in 32 (74.4%) of the MFS children. MFS diagnosis could not be made in five (15.6%) FBN1 variant-positive children. The most common cardinal finding is cardiac anomalies n = 38 (88.3%). The most common FBN1 pathogenic variant was c.1786 T > C/p.Cys596Arg n = 4 (12.5%). The distribution of pathogenic variants was as follows: 29 (90.6%) missense, 2 (6.3%) frameshift, and 1 (3.1%) nonsense. The numbers of AD and EL of the variant-positive children were 16 (50%) and 14 (43.7%), respectively. Ocular abnormalities were more common in children with FBN1-positive MFS (p = 0.009). There was no difference in the number of cardiac abnormalities between FBN1-positive and FBN1-negative MFS patients (p = 0.139).   Conclusion: This study examines the relationship between FBN1 variants and clinical features used as diagnostic criteria in MFS children. The findings emphasize the importance of long-term monitoring of heterogeneous clinical phenotypes and bioinformatic reanalysis in determining the genotype-phenotype relationship in children, as MFS symptoms can vary with age. What is Known: • Marfan syndrome has highly variable phenotypic heterogeneity. • The genotype-phenotype relationship in childhood Marfan syndrome is not clear enough due to the variation in the time of onset of the findings. What is New: • This article provides regional data for the field of research on genotype-phenotype relationships in childhood Marfan syndrome. • Long-term follow-up of clinical findings and bioinformatics reanalysis is an important requirement for a well-established genotype-phenotype relationship in childhood Marfan syndrome.

Wnt Signaling Inhibition Prevents Postnatal Inflammation and Disease Progression in Mouse Congenital Myxomatous Valve Disease.

BACKGROUND: Myxomatous valve disease (MVD) is the most common cause of mitral regurgitation, leading to impaired cardiac function and heart failure. MVD in a mouse model of Marfan syndrome includes valve leaflet thickening and progressive valve degeneration. However, the underlying mechanisms by which the disease progresses remain undefined. METHODS: Mice with Fibrillin 1 gene variant Fbn1C1039G/+ recapitulate histopathologic features of Marfan syndrome, and Wnt (Wingless-related integration site) signaling activity was detected in TCF/Lef-lacZ (T-cell factor/lymphoid enhancer factor-ß-galactosidase) reporter mice. Single-cell RNA sequencing was performed from mitral valves of wild-type and Fbn1C1039G/+ mice at 1 month of age. Inhibition of Wnt signaling was achieved by conditional induction of the secreted Wnt inhibitor Dkk1 (Dickkopf-1) expression in periostin-expressing valve interstitial cells of Periostin-Cre; tetO-Dkk1; R26rtTA; TCF/Lef-lacZ; Fbn1C1039G/+ mice. Dietary doxycycline was administered for 1 month beginning with MVD initiation (1-month-old) or MVD progression (2-month-old). Histological evaluation and immunofluorescence for ECM (extracellular matrix) and immune cells were performed. RESULTS: Wnt signaling is activated early in mitral valve disease progression, before immune cell infiltration in Fbn1C1039G/+ mice. Single-cell transcriptomics revealed similar mitral valve cell heterogeneity between wild-type and Fbn1C1039G/+ mice at 1 month of age. Wnt pathway genes were predominantly expressed in valve interstitial cells and valve endothelial cells of Fbn1C1039G/+ mice. Inhibition of Wnt signaling in Fbn1C1039G/+ mice at 1 month of age prevented the initiation of MVD as indicated by improved ECM remodeling and reduced valve leaflet thickness with decreased infiltrating macrophages. However, later, Wnt inhibition starting at 2 months did not prevent the progression of MVD. CONCLUSIONS: Wnt signaling is involved in the initiation of mitral valve abnormalities and inflammation but is not responsible for later-stage valve disease progression once it has been initiated. Thus, Wnt signaling contributes to MVD progression in a time-dependent manner and provides a promising therapeutic target for the early treatment of congenital MVD in Marfan syndrome.

Unraveling the genetic collagen connection: clinical and therapeutic insights on genetic connective tissue disorders.

Hereditary connective tissue disorders include more than 200 conditions affecting different organs and tissues, compromising the biological role of the extracellular matrix through interference in the synthesis, development, or secretion of collagen and/or its associated proteins. The clinical phenotype includes multiple signs and symptoms, usually nonspecific but of interest to rheumatologists because of musculoskeletal involvement. The patient´s journey to diagnosis is long, and physicians should include these disorders in their differential diagnoses of diseases with systemic involvement. In this review, insights for the diagnosis and treatment of osteogenesis imperfecta, hypermobility spectrum disorder/Ehlers-Danlos syndrome, Marfan, Loeys-Dietz, and Stickler syndromes are presented.

Quantitative measurement of dural ectasia: associations with clinical and genetic characteristics in Marfan syndrome.

PURPOSE: Dural ectasia (DE) may significantly impact Marfan syndrome (MFS) patients' quality of life due to chronic lower back pain, postural headache and urinary disorders. We aimed to evaluate the association of quantitative measurements of DE, and their evolution over time, with demographic, clinical and genetic characteristics in a cohort of MFS patients. METHODS: We retrospectively included 88 consecutive patients (39% females, mean age 37.1 ± 14.2 years) with genetically confirmed MFS who underwent at least one MRI or CT examination of the lumbosacral spine. Vertebral scalloping (VS) and dural sac ratio (DSR) were calculated from L3 to S3. Likely pathogenic or pathogenic FBN1 variants were categorized as either protein-truncating or in-frame. The latter were further classified according to their impact on the cysteine content of fibrillin-1. RESULTS: Higher values of the systemic score (revised Ghent criteria) were associated with greater DSR at lumbar (p < 0.001) and sacral (p = 0.021) levels. Patients with protein-truncating variants exhibited a greater annual increase in lumbar (p = 0.039) and sacral (p = 0.048) DSR. Mutations affecting fibrillin-1 cysteine content were linked to higher VS (p = 0.009) and DSR (p = 0.038) at S1, along with a faster increase in VS (p = 0.032) and DSR (p = 0.001) in the lumbar region. CONCLUSION: Our study shed further light on the relationship between genotype, dural pathology, and the overall clinical spectrum of MFS. The identification of protein-truncating variants and those impacting cysteine content may therefore suggest closer patient monitoring, in order to address potential complications associated with DE.

Single-Nucleus Multiomic Analyses Identifies Gene Regulatory Dynamics of Phenotypic Modulation in Human Aneurysmal Aortic Root.

Aortic root aneurysm is a potentially life-threatening condition that may lead to aortic rupture and is often associated with genetic syndromes, such as Marfan syndrome (MFS). Although studies with MFS animal models have provided valuable insights into the pathogenesis of aortic root aneurysms, this understanding of the transcriptomic and epigenomic landscape in human aortic root tissue remains incomplete. This knowledge gap has impeded the development of effective targeted therapies. Here, this study performs the first integrative analysis of single-nucleus multiomic (gene expression and chromatin accessibility) and spatial transcriptomic sequencing data of human aortic root tissue under healthy and MFS conditions. Cell-type-specific transcriptomic and cis-regulatory profiles in the human aortic root are identified. Regulatory and spatial dynamics during phenotypic modulation of vascular smooth muscle cells (VSMCs), the cardinal cell type, are delineated. Moreover, candidate key regulators driving the phenotypic modulation of VSMC, such as FOXN3, TEAD1, BACH2, and BACH1, are identified. In vitro experiments demonstrate that FOXN3 functions as a novel key regulator for maintaining the contractile phenotype of human aortic VSMCs through targeting ACTA2. These findings provide novel insights into the regulatory and spatial dynamics during phenotypic modulation in the aneurysmal aortic root of humans.

Coexistence of type 2 diabetes mellitus, arginine vasopressin deficiency, and Marfan syndrome: A case report.

Diabetes mellitus (DM) and arginine vasopressin deficiency (AVP-D) are characterized by polyuria. Marfan syndrome is an autosomal dominant disorder caused by pathogenetic variants in FBN1. Here, we report a patient with type 2 diabetes mellitus, AVP-D, and Marfan syndrome. Although the coexistence of type 2 diabetes mellitus and AVP-D is rare, for those patients with type 2 diabetes mellitus, the existence of AVP-D should be considered when polyuria is not in accordance with the blood glucose levels, especially for those with a low urine specific gravity. Specific symptoms or signs help to identify Marfan syndrome early, and genetic testing of the FBN1 pathogenetic variant helps to make a definitive diagnosis.

Pathogenic variants affecting the TB5 domain of the fibrillin-1 protein: not only in geleophysic/acromicric dysplasias but also in Marfan syndrome.

BACKGROUND: Marfan syndrome (MFS) is a multisystem disease with a unique combination of skeletal, cardiovascular and ocular features. Geleophysic/acromicric dysplasias (GPHYSD/ACMICD), characterised by short stature and extremities, are described as 'the mirror image' of MFS. The numerous FBN1 pathogenic variants identified in MFS are located all along the gene and lead to the same final pathogenic sequence. Conversely, in GPHYSD/ACMICD, the 28 known heterozygous FBN1 pathogenic variants all affect exons 41-42 encoding TGFß-binding protein-like domain 5 (TB5). METHODS: Since 1996, more than 5000 consecutive probands have been referred nationwide to our laboratory for molecular diagnosis of suspected MFS. RESULTS: We identified five MFS probands carrying distinct heterozygous pathogenic in-frame variants affecting the TB5 domain of FBN1. The clinical data showed that the probands displayed a classical form of MFS. Strikingly, one missense variant affects an amino acid that was previously involved in GPHYSD. CONCLUSION: Surprisingly, pathogenic variants in the TB5 domain of FBN1 can lead to two opposite phenotypes: GPHYSD/ACMICD and MFS, suggesting the existence of different pathogenic sequences with the involvement of tissue specificity. Further functional studies are ongoing to determine the precise role of this domain in the physiopathology of each disease.

In vivo phenotypic vascular dysfunction extends beyond the aorta in a mouse model for fibrillin-1 (Fbn1) mutation.

In individuals with Marfan Syndrome (MFS), fibrillin-1 gene (FBN1) mutations can lead to vascular wall weakening and dysfunction. The experimental mouse model of MFS (Fbn1C1041G/+) has been advantageous in investigating MFS-associated life-threatening aortic aneurysms. It is well established that the MFS mouse model exhibits an accelerated-aging phenotype in elastic organs like the aorta, lung, and skin. However, the impact of Fbn1 mutations on the in vivo function and structure of various artery types with the consideration of sex and age, has not been adequately explored in real-time and a clinically relevant context. In this study, we investigate if Fbn1 mutation contributes to sex-dependent alterations in central and cerebral vascular function similar to phenotypic changes associated with normal aging in healthy control mice. In vivo ultrasound imaging of central and cerebral vasculature was performed in 6-month-old male and female MFS and C57BL/6 mice and sex-matched 12-month-old (middle-aged) healthy control mice. Our findings confirm aortic enlargement (aneurysm) and wall stiffness in MFS mice, but with exacerbation in male diameters. Coronary artery blood flow velocity (BFV) in diastole was not different but left pulmonary artery BFV was decreased in MFS and 12-month-old control mice regardless of sex. At 6 months of age, MFS male mice show decreased posterior cerebral artery BFV as compared to age-matched control males, with no difference observed between female cohorts. Reduced mitral valve early-filling velocities were indicated in MFS mice regardless of sex. Male MFS mice also demonstrated left ventricular hypertrophy. Overall, these results underscore the significance of biological sex in vascular function and structure in MFS mice, while highlighting a trend of pre-mature vascular aging phenotype in MFS mice that is comparable to phenotypes observed in older healthy controls. Furthermore, this research is a vital step in understanding MFS's broader implications and sets the stage for more in-depth future analyses, while providing data-driven preclinical justification for re-evaluating diagnostic approaches and therapeutic efficacy.

miRNA Regulation of Cell Phenotype and Parietal Remodeling in Atherosclerotic and Non-Atherosclerotic Aortic Aneurysms: Differences and Similarities.

Aortic aneurysms are a serious health concern as their rupture leads to high morbidity and mortality. Abdominal aortic aneurysms (AAAs) and thoracic aortic aneurysms (TAAs) exhibit differences and similarities in their pathophysiological and pathogenetic features. AAA is a multifactorial disease, mainly associated with atherosclerosis, characterized by a relevant inflammatory response and calcification. TAA is rarely associated with atherosclerosis and in some cases is associated with genetic mutations such as Marfan syndrome (MFS) and bicuspid aortic valve (BAV). MFS-related and non-genetic or sporadic TAA share aortic degeneration with endothelial-to-mesenchymal transition (End-Mt) and fibrosis, whereas in BAV TAA, aortic degeneration with calcification prevails. microRNA (miRNAs) contribute to the regulation of aneurysmatic aortic remodeling. miRNAs are a class of non-coding RNAs, which post-transcriptionally regulate gene expression. In this review, we report the involvement of deregulated miRNAs in the different aortic remodeling characterizing AAAs and TAAs. In AAA, miRNA deregulation appears to be involved in parietal inflammatory response, smooth muscle cell (SMC) apoptosis and aortic wall calcification. In sporadic and MFS-related TAA, miRNA deregulation promotes End-Mt, SMC myofibroblastic phenotypic switching and fibrosis with glycosaminoglycan accumulation. In BAV TAA, miRNA deregulation sustains aortic calcification. Those differences may support the development of more personalized therapeutic approaches.

Ameliorative Effect of Coenzyme Q10 on Phenotypic Transformation in Human Smooth Muscle Cells with FBN1 Knockdown.

Mutations of the FBN1 gene lead to Marfan syndrome (MFS), which is an autosomal dominant connective tissue disorder featured by thoracic aortic aneurysm risk. There is currently no effective treatment for MFS. Here, we studied the role of mitochondrial dysfunction in the phenotypic transformation of human smooth muscle cells (SMCs) and whether a mitochondrial boosting strategy can be a potential treatment. We knocked down FBN1 in SMCs to create an MFS cell model and used rotenone to induce mitochondrial dysfunction. Furthermore, we incubated the shFBN1 SMCs with Coenzyme Q10 (CoQ10) to assess whether restoring mitochondrial function can reverse the phenotypic transformation. The results showed that shFBN1 SMCs had decreased TFAM (mitochondrial transcription factor A), mtDNA levels and mitochondrial mass, lost their contractile capacity and had increased synthetic phenotype markers. Inhibiting the mitochondrial function of SMCs can decrease the expression of contractile markers and increase the expression of synthetic genes. Imposing mitochondrial stress causes a double-hit effect on the TFAM level, oxidative phosphorylation and phenotypic transformation of FBN1-knockdown SMCs while restoring mitochondrial metabolism with CoQ10 can rapidly reverse the synthetic phenotype. Our results suggest that mitochondria function is a potential therapeutic target for the phenotypic transformation of SMCs in MFS.

The role of genetic testing in Marfan syndrome.

PURPOSE OF REVIEW: This review aims to delineate the genetic basis of Marfan syndrome (MFS) and underscore the pivotal role of genetic testing in the diagnosis, differential diagnosis, genotype-phenotype correlations, and overall disease management. RECENT FINDINGS: The identification of pathogenic or likely pathogenic variants in the FBN1 gene, associated with specific clinical features such as aortic root dilatation or ectopia lentis, is a major diagnostic criterion for MFS. Understanding genotype-phenotype correlations is useful for determining the timing of follow-up, guiding prophylactic aortic root surgery, and providing more precise information to patients and their family members during genetic counseling. Genetic testing is also relevant in distinguishing MFS from other conditions that present with heritable thoracic aortic diseases, allowing for tailored and individualized management. SUMMARY: Genetic testing is essential in different steps of the MFS patients' clinical pathway, starting from the phase of diagnosis to management and specific treatment.