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Mutations in the genes FBN1, TGFBR1, and TGFBR2 can result in heritable connective tissue disorders comprising the Marfan syndrome and the Loeys-Dietz syndrome. Dural ectasia is a characteristic manifestation of both syndromes. However, dural ectasia has not yet been investigated in connective tissue disorders that are unrelated to mutations in the FBN1, TGFBR1 or TGFBR2 genes. Here, we assessed dural ectasia in 33 individuals both with typical manifestations of heritable connective tissue disease and in whom mutations in all three genes had been excluded. We identified 19 individuals with dural ectasia (58%), who exhibited major skeletal manifestations of the Marfan syndrome more frequently than the remaining 14 persons without dural ectasia (p = 0.06). Moreover, only persons with dural ectasia fulfilled clinical criteria of the Marfan syndrome (p = 0.01). Conversely, aortic aneurysm (12 patients; p = 0.8), aortic dissection (five patients; p = 0.1), spontaneous dissection of the carotid arteries (five patients; p = 1), and mitral valve prolapse (13 patients; p = 0.4) were similarly frequent irrespective of dural ectasia. We conclude that dural ectasia is a marker for connective tissue disease which coincides with skeletal rather than with cardiovascular manifestations, and which may involve currently uncharacterized pathogenetic mechanisms and syndromes.

To evaluate corneal curvature, pachymetry, and endothelial cell density (ECD) in Marfan syndrome (MFS). A case-control study in which K values, pachymetry, and ECD were compared in 39 MFS eyes and 40 control eyes matched for age and refraction was conducted. MFS eyes with lens subluxation also were compared with eyes without subluxation. The mean K(med) value in MFS eyes was lower than in the control eyes, 42.2 ± 1.9 versus 43.4 ± 1.4 dioptres (D), respectively (p = 0.02). Fifteen MFS eyes (38%) and three control eyes (8%) had K(med) values below 41.5 D (p = 0.0012). MFS eyes had generally more corneal astigmatism than control eyes, 1.1 ± 0.9 versus 0.8 ± 0.4 D (p = 0.035), and MFS eyes with lens subluxation had more corneal astigmatism than those without, 1.6 ± 1.1 versus 0.6 ± 0.3 D (p = 0.0002). Nine MFS eyes with corneal astigmatism exceeding 1.5 D also had a subluxated lens. No eyes had keratoconus. The mean pachymetry value was lower in MFS eyes compared to the controls, 485 ± 54.5 versus 514 ± 37.3 μm (p = 0.007); 24 MFS eyes (62%) and 10 control eyes (25%) had measurements below 500 μm (p = 0.01). The mean ECD values were similar in MFS and control eyes, 2815 ± 430 versus 2858 ± 458 cells/mm(2) (p = 0.66). The mean K value, pachymetry, and ECD values did not differ between MFS eyes with and without lens subluxation. Decreased K values and pachymetry could indicate MFS regardless of subluxation. High corneal astigmatism is associated with subluxation in MFS. Subluxation should be identified in MFS eyes with high corneal astigmatism.

Objective: It has been firmly established that mutations in the gene for fibrillin 1, FBN1, cause Marfan syndrome (MFS). FBN1 mutations can also cause other phenotypes, such as ectopia lentis...

In order to evaluate the contribution of FBN1, FBN2, TGFBR1, and TGFBR2 mutations to the Marfan syndrome (MFS) phenotype, the four genes were analyzed by direct sequencing in 49 patients with MFS or suspected MFS as a cohort study. A total of 27 FBN1 mutations (22 novel) in 27 patients (55%, 27/49), 1 novel TGFBR1 mutation in 1 (2%, 1/49), and 2 recurrent TGFBR2 mutations in 2 (4%, 2/49) were identified. No FBN2 mutation was found. Three patients with either TGFBR1 or TGFBR2 abnormality did not fulfill the Ghent criteria, but expressed some overlapping features of MFS and Loeys-Dietz syndrome (LDS). In the remaining 19 patients, either of the genes did not show any abnormalities. This study indicated that FBN1 mutations were predominant in MFS but TGFBRs defects may account for approximately 5-10% of patients with the syndrome.

This editorial refers to ‘Genotype impacts survival in Marfan syndrome’, by R. Franken et al . [doi:10.1093/eurheartj/ehv739][1] Marfan syndrome (MFS) is an autosomal dominant inherited connective tissue disorder with the main manifestations in the skeletal (overgrowth), ocular (ectopia lentis), and cardiovascular system. The latter include predominantly mitral valve disease (prolapse with or without insufficiency) and aortic aneurysm most prominently at the level of the sinuses of Valvalva. The disease has an estimated prevalence between 1/3000 and 1/5000, irrespective of gender or ethnicity. The large majority of MFS patients will ultimately develop aortic aneurysm and, if undetected, be prone to aortic dissection, most commonly type A dissections starting from the dilated aortic root, but type B dissection have also been described. Since its initial description in 1898 by Antoine-Bernard Marfan, it took ∼100 years to discover the genetic basis of the condition. Dietz and colleagues demonstrated that mutations in the FBN1 gene, coding for the extracellular matrix protein fibrillin-1, are causal of the disease.1 Over the past 25 years, >3000 different FBN1 mutations have been described. With the advance of genetic technology, mutation detection is now feasible in >90–95% of MFS patients, and molecular testing has become an integral part of the diagnostic decision-making process. According to the revised Ghent Marfan nosology, a clinical diagnosis can be made if one of the four following rules in an index patient is fulfilled: (i) the presence of ectopia lentis and aortic root dilatation; (ii) aortic root dilatation and FBN1 mutation; (3) aortic root dilatation and systemic score; and (iv) ectopia lentis and FBN1 mutation.2 Although genetic analysis of FBN1 now contributes significantly to the diagnostic process, its … [1]: http://dx.doi.org/10.1093/eurheartj/ehv739

Fibrillin-1 is a ubiquitous extracellular matrix molecule that sequesters latent growth factor complexes. A role for fibrillin-1 in specifying tissue microenvironments has not been elucidated, even though the concept that fibrillin-1 provides extracellular control of growth factor signaling is currently appreciated. Mutations in FBN1 are mainly responsible for the Marfan syndrome (MFS), recognized by its pleiotropic clinical features including tall stature and arachnodactyly, aortic dilatation and dissection, and ectopia lentis. Each of the many different mutations in FBN1 known to cause MFS must lead to similar clinical features through common mechanisms, proceeding principally through the activation of TGFβ signaling. Here we show that a novel FBN1 mutation in a family with Weill-Marchesani syndrome (WMS) causes thick skin, short stature, and brachydactyly when replicated in mice. WMS mice confirm that this mutation does not cause MFS. The mutation deletes three domains in fibrillin-1, abolishing a binding site utilized by ADAMTSLIKE-2, -3, -6, and papilin. Our results place these ADAMTSLIKE proteins in a molecular pathway involving fibrillin-1 and ADAMTS-10. Investigations of microfibril ultrastructure in WMS humans and mice demonstrate that modulation of the fibrillin microfibril scaffold can influence local tissue microenvironments and link fibrillin-1 function to skin homeostasis and the regulation of dermal collagen production. Hence, pathogenetic mechanisms caused by dysregulated WMS microenvironments diverge from Marfan pathogenetic mechanisms, which lead to broad activation of TGFβ signaling in multiple tissues. We conclude that local tissue-specific microenvironments, affected in WMS, are maintained by a fibrillin-1 microfibril scaffold, modulated by ADAMTSLIKE proteins in concert with ADAMTS enzymes.

The results of direct DNA diagnostics in nine patients with Marfan syndrome, aged from two to 52 years old, and four unhealthy relatives with the same disease from two unrelated families have been presented for the first time in Russia. Eight mutations in the gene FBN1 were revealed. One patient demonstrated a substitution with unknown clinical importance, which was previously described in the SN P database as rsl 12287730 with a frequency of incidence of 0.1%. Out of the eight mutations, two (25%) were previously described, and the other six mutations (75%) were revealed for the first time. These mutations revealed by us were of the following types: three mutations (37.5%) produced a shift in the open reading frame (two deletions and one insertion), three mutations (12.5%) involved a splicing site, and one (12.5%) nonsense mutation was also noted. Our data contradict previous reports that claimed that the majority of mutations in the FBN1 gene represented missense mutations. Such inconsistency could result from a small size of the examined sample or from substitutions that produced alteration in the splicing site (as we have demonstrated here). The distribution of the revealed mutations was uniform along the whole gene. The results of the conducted comparative analysis of genetic and phenotypic indices was in complete agreement with previously reported results. The developed direct method of DNA diagnostics was fully informative, as we managed in all nine examined patients to confirm their clinical diagnosis using a molecular and genetic approach.

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

Identification of a novel mutation in FBN1 in a Chinese family with inherited ectopia lentis by targeted NGS

Marfan syndrome and Ehlers-Danlos syndrome represent two connective tissue vascular diseases requiring unique consideration in their vascular surgical care. A comprehensive national review encompassing all hospitalizations for the Marfan Syndrome and Ehlers-Danlos syndrome patient population is lacking. The National (Nationwide) Inpatient Sample from 2010 to 2014 was reviewed for all inpatient vascular surgery procedures including those with a diagnosis of Marfan syndrome and Ehlers-Danlos syndrome. National estimates of vascular surgery rates were generated from provided weights. Patient demographics, procedure type, and outcomes were assessed. There were 3103 Marfan syndrome and 476 Ehlers-Danlos syndrome vascular procedures identified as well as 3,895,381 vascular procedures in the remainder of population (control group). The percent of aortic procedures from all vascular procedures in Marfan syndrome (23.5%) and Ehlers-Danlos syndrome (23.5%) were 2.5-fold higher than controls (9.1%), p < 0.0001. Open aortic aneurysm repair was also significantly greater in both Marfan syndrome (16.8%) and Ehlers-Danlos syndrome (11.2%) compared to controls (4.4%), p < 0.0001. Endovascular aortic repair (p < 0.2302) was similar among the groups. Marfan syndrome (7.7%) and Ehlers-Danlos syndrome (5.1%) had more thoracic endovascular aortic repair performed than controls (0.7%), p < 0.0001. Percutaneous procedures were fewer in Marfan syndrome (6.3%) than controls (31.3%) and Ehlers-Danlos syndrome (26.3%), p < 0.0001, while repair of peripheral arteries was greater in Marfan syndrome (5.9%) and Ehlers-Danlos syndrome (4.1%) than controls (1.5%), p < 0.0001. For total aortic procedures, the mean age of aortic procedures was 68.2 years in controls vs 45.8 years in Marfan syndrome and 55.3 years in Ehlers-Danlos syndrome, p < 0.0001. Marfan syndrome and Ehlers-Danlos syndrome had fewer comorbidities overall, while controls had significantly higher rates of coronary artery disease (controls 39.9% vs Marfan syndrome 8.3% and Ehlers-Danlos syndrome 13.0%, p < 0.0001), peripheral vascular disease (controls 34.5% vs Marfan syndrome 4.2% and Ehlers-Danlos syndrome 8.7%, p < 0.0001), and diabetes (controls 20.6% vs Marfan syndrome 6.6 and Ehlers-Danlos syndrome 4.4%, p < 0.0001). Marfan syndrome and Ehlers-Danlos syndrome had higher overall complication rate (65.5% and 52.2%) compared to controls (44.6%), p < 0.0001. Postoperative hemorrhage was more likely in Marfan syndrome (42.9%) and Ehlers-Danlos syndrome (39.1%) than controls (22.2%), p < 0.0001. Increased respiratory failure was noted in Marfan syndrome (20.2%) vs controls (10.7%) and Ehlers-Danlos syndrome (8.7%), p = .0003. Finally, length of stay was increased in Marfan syndrome 12.5 days vs Ehlers-Danlos syndrome 7.4 days and controls 7.2 days (p < 0.0001) as well as a higher median costs of index hospitalization in Marfan syndrome ($57,084 vs Ehlers-Danlos syndrome $22,032 and controls $26,520, p < 0.0001). Patients with Marfan syndrome and Ehlers-Danlos syndrome differ from other patients undergoing vascular surgical procedures, with a significantly higher proportion of aortic procedures including open aneurysm repair and thoracic endovascular aortic repair. While they are younger with fewer comorbidities, due to the unique pathogenesis of their underlying connective tissue disorder, there is an overall higher rate of procedural complications and increased length of stay and cost for Marfan syndrome patients undergoing aortic surgery.

BackgroundBicuspid aortic valve (BAV) is the most frequent congenital heart disease with frequent involvement in thoracic aortic dilatation, aneurysm and dissection. Although BAV and Marfan syndrome (MFS) share some clinical features, and some MFS patients with BAV display mutations in FBN1, the gene encoding fibrillin-1, the genetic background of isolated BAV is poorly defined.MethodsTen consecutive BAV patients [8 men, age range 24–42 years] without MFS were clinically characterized. BAV phenotype and function, together with evaluation of aortic morphology, were comprehensively assessed by Doppler echocardiography. Direct sequencing of each FBN1 exon with flanking intron sequences was performed on eight patients.ResultsWe detected three FBN1 mutations in two patients (aged 24 and 25 years) displaying aortic root aneurysm ≥50 mm and moderate aortic regurgitation. In particular, one patient had two mutations (p.Arg2726Trp and p.Arg636Gly) one of which has been previously associated with variable Marfanoid phenotypes. The other patient showed a pArg529Gln substitution reported to be associated with an incomplete MFS phenotype.ConclusionsThe present findings enlarge the clinical spectrum of isolated BAV to include patients with BAV without MFS who have involvement of FBN1 gene. These results underscore the importance of accurate phenotyping of BAV aortopathy and of clinical characterization of BAV patients, including investigation of systemic connective tissue manifestations and genetic testing.

Thoracic aortic aneurysms in Marfan Syndrome (MFS) caused by mutations in FBN1 are associated with altered TGF-β signaling. Regulation of gene expression can occur at the level of microRNA, which can modify signaling pathways. We hypothesized that there would be altered microRNA expression in MFS that may alter the expression of signaling proteins. Total RNA was isolated from whole blood collected in PAXgene® tubes (PreAnalytiX), from 13 MFS patients with aortic dilatation (6F, 7M; Ao Diameter 44.4±6.0mm; Age 39±12yrs) and 10 normal controls (5F, 5M; Ao Diameter 32.3±5mm; Age 34±10yrs). The RNA was reverse transcribed with Human Pool A &amp; B primers and qPCR was performed on the subsequent cDNA using TaqMan® OpenArray® Human miRNA Panels (2454 targets) (ThermoFisher). microRNA expression was considered to be significantly altered if there was &gt;2 fold change (p&lt;0.05) compared to controls. microRNA that were identified as significantly altered were then validated with qPCR using targeted primers on an additional 33 MFS patients (15F, 21M; Ao Diameter 44.2±5.0mm; Age 37±13yrs). In MFS patients, the OpenArray® identified 30 microRNA were significantly altered (22 up regulated, 8 down regulated). Of these, 12 were confirmed to be altered using targeted qPCR (Graph 1). Three of these have previously been identified as modifiers of the TGF-β signaling pathway (miR 17, miR 93, miR 93*). Three were from the let-7 family (let-7e, let-7f, let-7g), which are involved in terminal cell differentiation and have been implicated in several cardiovascular disease processes. Another three have been shown to be dysregulated in various cardiovascular disease states including atherosclerotic thoracic aortic aneurysm and left ventricular hypertrophy (miR 208, miR 486, miR 378). This study provides novel evidence for adaptive responses at the post-transcriptional level of gene expression that may modulate aneurysm development in Marfan syndrome.

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. To expand the mutation spectrum of FBN1 gene and validate the pathogenicity of Marfan-related genes in patients with MFS and ocular manifestations. 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. 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. 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.

Mutations in the genes for transforming growth factor-beta receptor (TGFBR) have been identified in patients with Marfan syndrome (MFS) and Marfan-like connective tissue disorders. There are several syndromes associated with mutations in TGFBR genes, including Loeys-Dietz syndrome (LDS), MFS2, Furlong syndrome, and Shprintzen-Goldberg syndrome. However, with the exception of the first report by Loeys et al, the phenotypic features of patients with TGFBR gene mutations have not been precisely reported. A total of 18 patients suspected of having MFS were recruited and 7 were diagnosed with MFS and mutations in FBN1. Among the remaining 11 patients, 1 patient had mutations in TGFBR1, 2 had mutations in TGFBR2, and 1 had mutations in COL3A1. The clinical manifestations of the 3 patients with TGFBR gene mutations were examined according to the list of 36 clinical features described in the first report by Loeys et al. The clinical manifestations of these 3 patients differed from those previously observed in patients with MFS2, Furlong syndrome, and Shprintzen-Goldberg syndrome. Thus, the most probable diagnosis of these 3 patients was LDS, despite the fact that they presented with only a fraction of the 36 clinical features associated with LDS. Although the number of the patients was limited, the findings support the notion that mutations in the TGFBR gene may be associated with greater phenotypic heterogeneity than previously reported.

Marfan syndrome (MFS) is an autosomal genetic disease caused by FBN1 mutation. Patients with the same FBN1 mutation type exhibit different phenotypes, which indicates additional risk factors. Mitochondrial dysfunction was observed in the aorta of both MFS patients and Marfan murine models. Single-nucleotide variants in mitochondrial DNA (mtDNA) may have harmful consequences on a cell. This study investigates the association between mtDNA mutations and MFS. We analyzed mtDNA mutations in 48 healthy controls and 77 MFS patients, including seven mother-offspring pedigrees. Targeted sequencing of mitochondrial DNA was performed on whole blood samples from both healthy controls and MFS patients. Detected variants were validated using Sanger sequencing. Subsequently, variants were annotated, and conservation analysis and protein structural predictions were conducted. Three rare mtDNA mutations, m.279T > C, m.2361G > A and m.3316G > A, were identified in a family whose predominant phenotype was eye lesions. The MFS patients with these mutations had more severe symptoms than family members without the mutation. m.9738G > A was identified in a family whose dominant phenotype was aortic manifestation. A sporadic case with this rare mutation site has an aortic aneurysm. We also described the mutation frequency and mutation rate in MFS. The frequency of all solid variants, nonsynonymous variants, pathogenic or likely pathogenic variants and variants of uncertain significance was more abundant in MFS patients compared to the control group. The mutation rate of the coding region, MT-rRNA and MT-tRNA was higher in the MFS group. These data demonstrate frequent mitochondrial mutation in MFS and suggest that the mtDNA mutation might be a potential modifier of MFS phenotypes.