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Objective: Loeys-Dietz syndrome (LDS) is a heritable disorder of connective tissue closely related to Marfan syndrome (MFS). LDS is caused by loss-of-function variants of genes that encode components of transforming growth factor-β (TGF-β) signaling; nevertheless, LDS type 1/2 caused by TGFBR1/2 pathogenic variants is frequently found to have paradoxical increases in TGF-β signaling in the aneurysmal aortic wall. Here, we present a Japanese LDS family having a novel SMAD3 variant., Methods: The proband was tested via clinical, genetic, and histological analyses. In vitro analysis was performed for pathogenic evaluation., Results: The novel heterozygous missense variant of SMAD3 [c.1262G>A, p.(Cys421Tyr)], located just upstream of the C-terminal Ser423-X-Ser425 phosphorylation motif, was found in this instance of LDS type 3. This variant led to reduced phospho-SMAD3 (Ser423/Ser425) levels and transcription activity in vitro; however, a paradoxical upregulation of TGF-β signaling was evident in the aortic wall., Conclusions: Our results revealed the presence of TGF-β paradox in this case with the novel loss-of-function SMAD3 variant. The precise mechanism underlying the paradox is unknown, but further research is warranted to clarify the influence of the SMAD3 variant type and location on the LDS3 phenotype as well as the molecular mechanism leading to LDS3 aortopathy., (© 2023 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals LLC.)

Pathogenic variants in TGFBR1 are a common cause of Loeys-Dietz syndrome (LDS) characterized by life-threatening aortic and arterial disease. Generally, these are missense changes in highly conserved amino acids in the serine-threonine kinase domain. Conversely, nonsense, frameshift, or specific missense changes in the ligand-binding extracellular domain cause multiple self-healing squamous epithelioma (MSSE) lacking the cardiovascular phenotype. Here, we report on two novel variants in the penultimate exon 8 of TGFBR1 were identified in 3 patients from two unrelated LDS families: both were predicted to cause frameshift and premature stop codons (Gln448Profs*15 and Cys446Asnfs*4) resulting in truncated TGFBR1 proteins lacking the last 43 and 56 amino acid residues, respectively. These were classified as variants of uncertain significance based on current criteria. Transcript expression analyses revealed both mutant alleles escaped nonsense-mediated mRNA decay. Functional characterization in patient's dermal fibroblasts showed paradoxically enhanced TGFβ signaling, as observed for pathogenic missense TGFBR1 changes causative of LDS. In summary, we expanded the allelic repertoire of LDS-associated TGFBR1 variants to include truncating variants escaping nonsense-mediated mRNA decay. Our data highlight the importance of functional studies in variants interpretation for correct clinical diagnosis., (© 2022. The Author(s), under exclusive licence to European Society of Human Genetics.)

Aims: To assess aortic flow and stiffness in patients with Loeys-Dietz syndrome (LDS) by 4D flow and cine cardiovascular magnetic resonance (CMR) and compare the results with those of healthy volunteers (HV) and Marfan syndrome (MFS) patients., Methods and Results: Twenty-one LDS and 44 MFS patients with no previous aortic dissection or surgery and 35 HV underwent non-contrast-enhanced 4D flow CMR. In-plane rotational flow (IRF), systolic flow reversal ratio (SFRR), and aortic diameters were obtained at 20 planes from the ascending (AAo) to the proximal descending aorta (DAo). IRF and SFRR were also quantified for aortic regions (proximal and distal AAo, arch and proximal DAo). Peak-systolic wall shear stress (WSS) maps were also estimated. Aortic stiffness was quantified using pulse wave velocity (PWV) and proximal AAo longitudinal strain. Compared to HV, LDS patients had lower rotational flow at the distal AAo (P = 0.002), arch (P = 0.002), and proximal DAo (P < 0.001) even after adjustment for age, stroke volume, and local diameter. LDS patients had higher SFRR in the proximal DAo compared to both HV (P = 0.024) and MFS patients (P = 0.015), even after adjustment for age and local diameter. Axial and circumferential WSS in LDS patients were lower than in HV. AAo circumferential WSS was lower in LDS compared to MFS patients. AAo and DAo PWV and proximal AAo longitudinal strain revealed stiffer aortas in LDS patients compared to HV (P = 0.007, 0.005, and 0.029, respectively) but no differences vs. MFS patients., Conclusion: Greater aortic stiffness as well as impaired IRF and WSS were present in LDS patients compared to HV. Conversely, similar aortic stiffness and overlapping aortic flow features were found in Loeys-Dietz and Marfan patients., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2021. For permissions, please email: journals.permissions@oup.com.)

The aim of this article is to describe neurovascular findings in patients with Loeys Dietz syndrome type III and their possible clinical impact. Loeys Dietz syndrome type III, caused by pathogenic SMAD3 variants, is an autosomal dominant syndrome characterized by aneurysms and arterial tortuosity in combination with osteoarthritis. Neurovascular abnormalities have been described in other heritable aortic syndromes, however, reliable data in Loeys Dietz syndrome type III is missing. In our tertiary center, all adult patients with confirmed Loeys Dietz syndrome type III are followed in a standardized aorta outpatient clinic including Computed Tomography Angiography (CTA) of the head and neck region at baseline and (tri) yearly during follow-up. We performed an analysis of the neurovascular imaging findings and clinical follow-up. The primary outcome was a combined endpoint of mortality, dissection, cerebral vascular event and intervention. In addition, tortuosity and vascular growth were assessed. In total 26 patients (mean age 38.4 years, 38.5% males) underwent 102 (mean 3.9 (1-8) per patient) neurovascular Computed Tomography Angiography scans between 2010 and 2021. In 84.6% some form of neurovascular abnormality was found. The abnormalities at baseline were aneurysm (26.9%) dissection flap (7.7%), arterial tortuosity (61.5%), arterial coiling (23.1%) and arterial kinking (3.8%). During follow up (mean 8.85 (1-11) years) one patient suffered from sudden death and one patient needed a neuro-radiological intervention. No cerebral bleeding or stroke occurred. In conclusion, neurovascular imaging in Loeys Dietz syndrome type III patients revealed abnormalities such as aneurysm, tortuosity, coiling and kinking in the vast majority of patients, but clinical events were rare. Neurovascular screening and follow up is advised in all Loeys Dietz syndrome type III patients., (Copyright © 2022 The Authors. Published by Elsevier Masson SAS.. All rights reserved.)

Background: Loeys-Dietz syndrome (LDS) is an inherited disorder predisposing individuals to thoracic aortic aneurysm and dissection. Currently, there are no medical treatments except surgical resection. Although the genetic basis of LDS is well-understood, molecular mechanisms underlying the disease remain elusive, impeding the development of a therapeutic strategy. In addition, aortic smooth muscle cells (SMCs) have heterogenous embryonic origins, depending on their spatial location, and lineage-specific effects of pathogenic variants on SMC function, likely causing regionally constrained LDS manifestations, have been unexplored., Methods: We identified an LDS family with a dominant pathogenic variant in the TGFBR1 gene ( TGFBR1 A230T ) causing aortic root aneurysm and dissection. To accurately model the molecular defects caused by this mutation, we used human induced pluripotent stem cells from a subject with normal aorta to generate human induced pluripotent stem cells carrying TGFBR1 A230T , and corrected the mutation in patient-derived human induced pluripotent stem cells using CRISPR-Cas9 gene editing. After their lineage-specific SMC differentiation through cardiovascular progenitor cell (CPC) and neural crest stem cell lineages, we used conventional molecular techniques and single-cell RNA sequencing to characterize the molecular defects. The resulting data led to subsequent molecular and functional rescue experiments using activin A and rapamycin., Results: Our results indicate the TGFBR1 A230T mutation impairs contractile transcript and protein levels, and function in CPC-SMC, but not in neural crest stem cell-SMC. Single-cell RNA sequencing results implicate defective differentiation even in TGFBR1 A230T/+ CPC-SMC including disruption of SMC contraction and extracellular matrix formation. Comparison of patient-derived and mutation-corrected cells supported the contractile phenotype observed in the mutant CPC-SMC. TGFBR1 A230T selectively disrupted SMAD3 (SMAD family member 3) and AKT (AKT serine/threonine kinase) activation in CPC-SMC, and led to increased cell proliferation. Consistently, single-cell RNA sequencing revealed molecular similarities between a loss-of-function SMAD3 mutation ( SMAD3 c.652delA/+ ) and TGFBR1 A230T/+ . Last, combination treatment with activin A and rapamycin during or after SMC differentiation significantly improved the mutant CPC-SMC contractile gene expression and function, and rescued the mechanical properties of mutant CPC-SMC tissue constructs., Conclusions: This study reveals that a pathogenic TGFBR1 variant causes lineage-specific SMC defects informing the etiology of LDS-associated aortic root aneurysm. As a potential pharmacological strategy, our results highlight a combination treatment with activin A and rapamycin that can rescue the SMC defects caused by the variant.

Heritable Connective Tissue Disorders (HCTD) show an overlap in the physical features that can evolve in childhood. It is unclear to what extent children with HCTD experience burden of disease. This study aims to quantify fatigue, pain, disability and general health with standardized validated questionnaires., Methods: This observational, multicenter study included 107 children, aged 4-18 years, with Marfan syndrome (MFS), 58%; Loeys-Dietz syndrome (LDS), 7%; Ehlers-Danlos syndromes (EDS), 8%; and hypermobile Ehlers-Danlos syndrome (hEDS), 27%. The assessments included PROMIS Fatigue Parent-Proxy and Pediatric self-report, pain and general health Visual-Analogue-Scales (VAS) and a Childhood Health Assessment Questionnaire (CHAQ)., Results: Compared to normative data, the total HCTD-group showed significantly higher parent-rated fatigue T-scores ( M = 53 ( SD = 12), p = 0.004, d = 0.3), pain VAS scores ( M = 2.8 ( SD = 3.1), p < 0.001, d = 1.27), general health VAS scores ( M = 2.5 ( SD = 1.8), p < 0.001, d = 2.04) and CHAQ disability index scores ( M = 0.9 ( SD = 0.7), p < 0.001, d = 1.23). HCTD-subgroups showed similar results. The most adverse sequels were reported in children with hEDS, whereas the least were reported in those with MFS. Disability showed significant relationships with fatigue ( p < 0.001, r s = 0.68), pain ( p < 0.001, r s = 0.64) and general health ( p < 0.001, r s = 0.59)., Conclusions: Compared to normative data, children and adolescents with HCTD reported increased fatigue, pain, disability and decreased general health, with most differences translating into very large-sized effects. This new knowledge calls for systematic monitoring with standardized validated questionnaires, physical assessments and tailored interventions in clinical care.

Purpose: To identify differences in surgical outcomes between patients with transforming growth factor-beta receptor (TGFBR) 1 and TGFBR2 mutations in Loeys-Dietz syndrome (LDS)., Methods: In all, 22 LDS patients between 1998 and 2015 were divided into the two groups: TGFBR1 (n = 11) and TGFBR2 mutation (n = 11)., Results: The freedom from aortic reoperation was similar between the two groups (p = 0.19, log-rank). In the subanalysis, the freedom from aortic reoperation was lower in female patients with TGFBR2 mutations (n = 6) than in other patients (p = 0.08). The freedom from aortic dissection (AD) after the initial surgery was also lower in female patients with TGFBR2 mutation than in other patients (p = 0.025). All patients with TGFBR2 mutations revealed grade III cystic medial necrosis (CMN), whereas 67% of patients with TGFBR1 mutations showed CMN (p = 0.033) and only one patient had grade III (p <0.001)., Conclusion: LDS patients with TGFBR2 mutations had higher grade of CMN than those of TGFBR1 mutations. In particular, in female patients with TGFBR2 mutations, AD after the initial surgery and reoperation were more frequent than those of other LDS patients.

Background and Purpose: The association of arterial tortuosity and connective tissue diseases is widely reported in the literature, but only a few studies were based on a quantitative evaluation of this arterial phenotype, and none of the latter examined the intracranial vasculature. The aim of this study was to evaluate the degree of intracranial arterial tortuosity in patients with Marfan syndrome and those with Loeys-Dietz syndrome, and to assess its usefulness in the differential diagnosis., Materials and Methods: We performed a retrospective analysis of 68 patients with genetically confirmed Marfan syndrome ( n  = 36) or Loeys-Dietz syndrome ( n  = 32), who underwent at least 1 MRA of the brain at our institution. Fifty-two controls were randomly selected among patients who presented with headache and without any known comorbidity. Tortuosity indexes of 4 intracranial arterial segments were measured on a 3D volume-rendered angiogram by using the following formula: [Formula: see text]., Results: Both Marfan syndrome and Loeys-Dietz syndrome showed a significantly higher tortuosity index compared with controls in all examined vessels. The tortuosity index of the vertebrobasilar system showed an excellent interrater reliability (intraclass correlation coefficient, 0.99) and was the strongest independent predictor of Loeys-Dietz syndrome in patients with connective tissue disease ( P = .002), with a 97% specificity for this pathology when its value was > 60., Conclusions: The tortuosity index of intracranial arteries is an easily calculated and highly reproducible measure, which shows a high specificity for Marfan syndrome and Loeys-Dietz syndrome and may be useful in differentiating these 2 entities., (© 2020 by American Journal of Neuroradiology.)

Background: Pathogenic SMAD3 variants are responsible for a cardiovascular phenotype, mainly thoracic aortic aneurysms and dissections. Precocious identification of the vascular risk such as aortic dilatation in mutated patients has a major impact in terms of management, particularly to avoid dissection and sudden death. These vascular damages are classically associated with premature osteoarthritis and skeletal abnormalities. However, variable expressivity and incomplete penetrance are common with SMAD3 variants., Methods: To investigate the clinical variability observed within SMAD3 patients, we reviewed the phenotypic and genetic data of 22 new patients from our Centre and of 133 patients reported in the literature. From this cohort of 155 mutated individuals, we first aimed to delineate an estimated frequency of the main clinical signs associated with SMAD3 pathogenic variants and, then, to look for genotype-phenotype correlations, mainly to see if the aortic phenotype (AP) could be predicted by the SMAD3 variant type., Results: We showed, herein, the absence of correlation between the SMAD3 variant type and the occurrence of an AP in patients., Conclusion: Therefore, this report brings additional data for the genotype-phenotype correlations of SMAD3 variants and the need to explore in more detail the effects of genetic modifiers that could influence the phenotype., (© 2020 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.)

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

Background: Pathogenic variants in the SMAD3 gene affecting the TGF-β/SMAD3 signaling pathway with aortic vessel involvement cause Loeys-Dietz syndrome 3, also known as aneurysms-osteoarthritis syndrome., Methods: Description of clinical history of a family in Sweden using clinical data, DNA sequencing, bioinformatics, and pedigree analysis., Results: We report a novel SMAD3 variant, initially classified as a genetic variant of uncertain clinical significance (VUS), and later found to be co-segregating with aortic dissection in the family. The index patient presented with a dissecting aneurysm of the aorta including the ascending, descending, and abdominal parts. Genotype analysis revealed a heterozygous missense SMAD3 variant: NM&#95;005902.3(SMAD3): c.11576G > C (p.Arg386Thr). The same variant was also identified in a 30 years old formalin-fixed paraffin-embedded block of tissue from a second cousin, who died at 26 years of age from a dissecting aneurysm of the aorta., Conclusion: A "variant of uncertain significance" according to the ACMG guidelines has always a scope for reappraisal. Genetic counselling to relatives, and the offering of surveillance service is important to families with aortic aneurysm disease. The report also highlight the potential use of FFPE analysis from deceased relatives to help in the interpretation of variants., (© 2019 The Authors. Molecular Genetics & Genomic Medicine published by Wiley Periodicals, Inc.)

Background: Loeys-Dietz syndrome (LDS) is a rare connective tissue disorder for which 6 genes in the TGF-β pathway have been identified as causative. With the widespread use of genetic testing, the range of known clinical and genetic profiles has broadened, but these features have not been fully elucidated thus far., Methods and Results: Using gene panel sequencing or whole exome sequencing, we identified 54 unique rare variants in LDS genes in 57 patients with thoracic aneurysms/dissections, including 27 pathogenic mutations (P + LP) and 27 variants of unknown significance (VUS LP  + VUS). Genotype-phenotype correlation analysis revealed that carriers with P/LP/ VUS LP variants in TGFBR1/TGFBR2/SMAD3 genes had significantly more severe cardiovascular features (cardiovascular death/dissection) than carriers with VUSs in these 3 genes at an early age and had less favorable event-free survival. Additionally, carriers with VUS in combination with other risk factors, such as hypertension, might be prone to developing an aortic dissection, as indicated by the fact that 5/8 (62.5%) patients with VUSs in our cohort developed aortic dissections in the presence of hypertension, compared with 25.0% (3/12) in the absence of hypertension (p = 0.047)., Conclusions: To date, this was the largest cohort of LDS patients ever reported in China, and the present study expanded the known mutation and phenotypic spectra of LDS, which might help refine our knowledge of LDS.

Background: Loeys-Dietz syndrome (LDS) is a rare connective tissue disorder whose oral manifestations and dental phenotypes have not been well-characterized. The aim of this study was to explore the influence of oral manifestations on oral health-related quality of life (OHRQoL) in LDS patients., Material and Methods: LDS subjects were assessed by the craniofacial team at the National Institutes of Health Clinical Center Dental Clinic between June 2015 and January 2018. Oral Health Impact Profile (OHIP-14) questionnaire, oral health self-care behavior questionnaire and a comprehensive dental examination were completed for each subject. OHRQoL was assessed using the OHIP-14 questionnaire with higher scores corresponding to worse OHRQoL. Regression models were used to determine the relationship between each oral manifestation and the OHIP-14 scores using a level of significance of p ≤ 0.05., Results: A total of 33 LDS subjects (51.5% female) aged 3-57 years (19.6 ± 15.1 years) were included in the study. The OHIP-14 scores (n = 33) were significantly higher in LDS subjects (6.30 [SD 6.37]) when compared to unaffected family member subjects (1.50 [SD 2.28], p < 0.01), and higher than the previously reported scores of the general U.S. population (2.81 [SD 0.12]). Regarding oral health self-care behavior (n = 32), the majority of LDS subjects reported receiving regular dental care (81%) and maintaining good-to-excellent daily oral hygiene (75%). Using a crude regression model, worse OHRQoL was found to be associated with dental hypersensitivity (β = 5.24; p < 0.05), temporomandibular joints (TMJ) abnormalities (β = 5.92; p < 0.01), self-reported poor-to-fair oral health status (β = 6.77; p < 0.01), and cumulation of four or more oral manifestations (β = 7.23; p < 0.001). Finally, using a parsimonious model, self-reported poor-to-fair oral health status (β = 5.87; p < 0.01) and TMJ abnormalities (β = 4.95; p < 0.01) remained significant., Conclusions: The dental hypersensitivity, TMJ abnormalities, self-reported poor-to-fair oral health status and cumulation of four-or-more oral manifestations had significant influence on worse OHRQoL. Specific dental treatment guidelines are necessary to ensure optimal quality of life in patients diagnosed with LDS.

Loeys-Dietz syndrome (LDS) is a connective tissue disorder first described in 2005 featuring aortic/arterial aneurysms, dissections, and tortuosity associated with craniofacial, osteoarticular, musculoskeletal, and cutaneous manifestations. Heterozygous mutations in 6 genes ( TGFBR1/2, TGFB2/3, SMAD2/3 ), encoding components of the TGF-β pathway, cause LDS. Such genetic heterogeneity mirrors broad phenotypic variability with significant differences, especially in terms of the age of onset, penetrance, and severity of life-threatening vascular manifestations and multiorgan involvement, indicating the need to obtain genotype-to-phenotype correlations for personalized management and counseling. Herein, we report on a cohort of 34 LDS patients from 24 families all receiving a molecular diagnosis. Fifteen variants were novel, affecting the TGFBR1 (6), TGFBR2 (6), SMAD3 (2), and TGFB2 (1) genes. Clinical features were scored for each distinct gene and matched with literature data to strengthen genotype-phenotype correlations such as more severe vascular manifestations in TGFBR1/2 -related LDS. Additional features included spontaneous pneumothorax in SMAD3 -related LDS and cervical spine instability in TGFB2 -related LDS. Our study broadens the clinical and molecular spectrum of LDS and indicates that a phenotypic continuum emerges as more patients are described, although genotype-phenotype correlations may still contribute to clinical management., Competing Interests: All authors declare that there is no conflict of interest concerning this work.

The aortic root is the predominant site for development of aneurysm caused by heterozygous loss-of-function mutations in positive effectors of the transforming growth factor-β (TGF-β) pathway. Using a mouse model of Loeys-Dietz syndrome (LDS) that carries a heterozygous kinase-inactivating mutation in TGF-β receptor I, we found that the effects of this mutation depend on the lineage of origin of vascular smooth muscle cells (VSMCs). Secondary heart field-derived (SHF-derived), but not neighboring cardiac neural crest-derived (CNC-derived), VSMCs showed impaired Smad2/3 activation in response to TGF-β, increased expression of angiotensin II (AngII) type 1 receptor (Agtr1a), enhanced responsiveness to AngII, and higher expression of TGF-β ligands. The preserved TGF-β signaling potential in CNC-derived VSMCs associated, in vivo, with increased Smad2/3 phosphorylation. CNC-, but not SHF-specific, deletion of Smad2 preserved aortic wall architecture and reduced aortic dilation in this mouse model of LDS. Taken together, these data suggest that aortic root aneurysm predisposition in this LDS mouse model depends both on defective Smad signaling in SHF-derived VSMCs and excessive Smad signaling in CNC-derived VSMCs. This work highlights the importance of considering the regional microenvironment and specifically lineage-dependent variation in the vulnerability to mutations in the development and testing of pathogenic models for aortic aneurysm.

Background: Loeys-Dietz syndrome (LDS) is a rare multisystemic disorder characterized by vascular and skeletal abnormalities, with considerable intra- and interfamilial variability., Case Presentation: We report the case of an 8-year-old male with clinical features of two distinct genetic disorders, namely LDS, manifesting in the first months by progressive aortic root dilatation, arterial tortuosity, bifid uvula, and inguinal hernias and oculocutaneous albinism (OCA) manifesting by white hair and skin that does not tan, nystagmus, reduced iris pigment with iris translucency, and reduced retinal pigment). We identified previously reported, homozygous mutations of TYR, c.1A > G (p.Met1Val) and heterozygous, missense mutation of TGFBR1, c.1460G > A (p.Arg487Gln). Family history revealed that his mother underwent multiple surgical repairs for recurrent hemorrhage originating from the buccal artery. Molecular studies confirmed a maternally inherited low grade TGFBR1 mutation somatic mosaicism (18% in peripheral blood leukocytes, 18% in buccal cells and 10% in hair root cells). Maternal cardiac investigations revealed peculiar cardiovascular features: mild tortuosity at the aortic arch, dilatation of the proximal abdominal aorta, multiple deep left ventricular myocardial crypts, and dysplastic mitral valve. TGFBR2 germline mosaicism has been described in three fathers of children carrying TGFBR2 mutations but, to the best of our knowledge, no case of maternally inherited TGFBR1 mutation mosaicism has been reported so far., Conclusions: This case report suggests that individuals with somatic mosaicism might be at risk for mild and unusual forms of LDS but germline mosaicism can lead to full blown picture of the disease in offspring.

Variants in TGFBR1 have been reported to induce two completely distinct diseases, namely Loeys-Dietz syndrome (LDS) and multiple self-healing squamous epithelioma (MSSE). However, detailed mechanisms underlying this effect remain unknown. We report a Japanese familial case of LDS with a novel splice donor site variant in TGFBR1 gene (c.973 + 1 G > A; NG&#95;007461.1). The intronic variant was predicted to mediate in-frame exon 5 skipping within the serine/threonine kinase (STK) domain, which may also be mediated by a similar TGFBR1 variant of a splice acceptor site in intron 4 (c.806-2 A > C), identified in a British familial case of MSSE. Therefore, ex vivo splicing and functional assays were performed in mammalian cells to evaluate the effect of these sequence variants. The MSSE variant activated a cryptic acceptor site at 76 bp downstream of the 3' natural splice acceptor site, which produced an out-of-frame transcript (r.807&#95;882del, p.Asn270Thrfs*8). In contrast, the LDS variant generated two types of in-frame transcription products, r.[806&#95;973del, 965&#95;973 del], and produced two functionally inactivated proteins, p.[Asp269&#95;Gln324del, Thr323&#95;Gly325del], as a result of exon 5 skipping and the activation of a cryptic donor splice site at 9 bp upstream of the 5' natural splice donor site, respectively. Our results support the previously proposed but not yet approved mechanism that dominant-negative and truncating variants in STK domain induce LDS and MSSE, respectively.

External aortic wrapping may overcompress the aortic wall. An 18-year-old man underwent valve-sparing aortic root replacement for annuloaortic ectasia caused by Loeys-Dietz syndrome. External Dacron graft wrapping was performed to protect the ascending aorta. A year later, he underwent mitral valve repair. Intraoperatively, after unwrapping the external graft, the wrapped ascending aortic wall appeared necrotic. Histopathology showed damaged smooth muscle cells in the adventitia and outer media with unaffected inner layers and an intact intimal surface. Ischaemic necrosis of the aortic wall was associated with arterial insufficiency secondary to overcompression of the aortic wall that was already weakened by Loeys-Dietz syndrome. We describe a patient with Loeys-Dietz syndrome in whom pathognomonic necrosis in the wrapped aortic wall was observed histopathologically.

Central corneal thickness (CCT) is a highly heritable trait associated with complex eye diseases such as keratoconus and glaucoma. We perform a genome-wide association meta-analysis of CCT and identify 19 novel regions. In addition to adding support for known connective tissue-related pathways, pathway analyses uncover previously unreported gene sets. Remarkably, >20% of the CCT-loci are near or within Mendelian disorder genes. These included FBN1, ADAMTS2 and TGFB2 which associate with connective tissue disorders (Marfan, Ehlers-Danlos and Loeys-Dietz syndromes), and the LUM-DCN-KERA gene complex involved in myopia, corneal dystrophies and cornea plana. Using index CCT-increasing variants, we find a significant inverse correlation in effect sizes between CCT and keratoconus (r = -0.62, P = 5.30 × 10 -5 ) but not between CCT and primary open-angle glaucoma (r = -0.17, P = 0.2). Our findings provide evidence for shared genetic influences between CCT and keratoconus, and implicate candidate genes acting in collagen and extracellular matrix regulation.

Loeys-Dietz syndrome (LDS) is an autosomal-dominant connective tissue disorder, commonly caused by genetic mutation of transforming growth factor-beta receptor (TGFBR)-1 or TGFBR2. This study describes the generation of human induced pluripotent stem cells (hiPSCs) from peripheral blood mononuclear cells obtained from an LDS patient with TGFBR2 mutation (R193W). Analysis confirmed the cells had a normal karyotype, expressed typical pluripotency markers, had the ability to differentiate into all three germ layers in vivo, and retained the TGFBR2 mutation from the derived hiPSCs. This iPSC line represents a potentially useful tool for investigating LDS disease mechanisms., (Copyright © 2017. Published by Elsevier B.V.)

Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder with a range of cardiovascular, skeletal, craniofacial and cutaneous manifestations. LDS type 4 is caused by mutations in TGFβ ligand 2 (TGFB2) and based on the family pedigrees described to date, appears to have a milder clinical phenotype, often presenting with isolated aortic disease. We sought to investigate its molecular basis in a new pedigree. We identified a missense variant p.(Arg320Cys) (NM&#95;003238.3) in a highly evolutionary conserved region of TGFB2 in a new LDS type 4 pedigree with multiple cases of aortic aneurysms and dissections. There was striking upregulation of TGFB1 and TGFB2 expression on immunofluorescent staining, and western blotting of the aortic tissue from the index case confirming the functional importance of the variant. This case highlights the striking paradox of predicted loss-of-function mutations in TGFB2 causing enhanced TGFβ signaling in this emerging familial aortopathy., Competing Interests: The authors declare no conflict of interest.

Background: The Loeys-Dietz syndrome (LDS) is a rare autosomal dominant disorder characterized by thoracic aortic aneurysm and dissection and widespread systemic connective tissue involvement. LDS type 1 to 4 are caused by mutations in genes of the TGF-β signaling pathway: TGFBR1 and TGFBR2 encoding the TGF-β receptor (LDS1 and LDS2), SMAD3 encoding the TGF-β receptor cytoplasmic effector (LDS3), and TGFB2 encoding the TGF-β2 ligand (LDS4). LDS4 represents the mildest end of the LDS spectrum, since aneurysms are usually observed in fourth decade and the progression of the disease is slower than in the other forms., Case Presentation: We report the clinical and molecular findings of an LDS4 Italian family. Genetic testing included TGFBR1, TGFBR2, SMAD3, and TGFB2 analysis by Sanger sequencing. In order to verify the effect of the identified splice mutation, RT-PCR analysis was performed.The proband, a 57-year-old woman, showed high palate, hypoplasic uvula, easy bruising, joint hypermobility, chronic pain, scoliosis, multiple relapsing hernias, dural ectasia, and mitral valve prolapse. Magnetic resonance angiography revealed tortuosity and ectasia of carotid, vertebral, cerebral, and segmental pulmonary arteries. Arterial aneurysm and dissection never occurred. Her 39- and 34-year-old daughters presented with a variable degree of musculoskeletal involvement. Molecular analysis disclosed the novel c.839-1G>A splice site mutation in the TGFB2 gene. This mutation activates a cryptic splice acceptor site in exon 6 leading to frameshift, premature termination codon and haploinsufficiency (p.Gly280Aspfs*41)., Conclusions: Our data confirm that loss-of-function mutations in TGFB2 gene do not always lead to aggressive vascular phenotypes and that articular and skeletal signs are prevalent, therefore suggesting that LDS4 must be considered in patients with sparse signs of LDS and related disorders also in the absence of vascular events.

Loeys-Dietz syndrome is a connective tissue disorder predisposing individuals to aortic and arterial aneurysms. Presenting with a wide spectrum of multisystem involvement, medical management for some individuals is complex. This review of literature and expert opinion aims to provide medical guidelines for care of individuals with Loeys-Dietz syndrome.

Loeys-Dietz syndrome (LDS) is a connective tissue disorder that is characterized by a high risk for aneurysm and dissection throughout the arterial tree and phenotypically resembles Marfan syndrome. LDS is caused by heterozygous missense mutations in either TGF-β receptor gene (TGFBR1 or TGFBR2), which are predicted to result in diminished TGF-β signaling; however, aortic surgical samples from patients show evidence of paradoxically increased TGF-β signaling. We generated 2 knockin mouse strains with LDS mutations in either Tgfbr1 or Tgfbr2 and a transgenic mouse overexpressing mutant Tgfbr2. Knockin and transgenic mice, but not haploinsufficient animals, recapitulated the LDS phenotype. While heterozygous mutant cells had diminished signaling in response to exogenous TGF-β in vitro, they maintained normal levels of Smad2 phosphorylation under steady-state culture conditions, suggesting a chronic compensation. Analysis of TGF-β signaling in the aortic wall in vivo revealed progressive upregulation of Smad2 phosphorylation and TGF-β target gene output, which paralleled worsening of aneurysm pathology and coincided with upregulation of TGF-β1 ligand expression. Importantly, suppression of Smad2 phosphorylation and TGF-β1 expression correlated with the therapeutic efficacy of the angiotensin II type 1 receptor antagonist losartan. Together, these data suggest that increased TGF-β signaling contributes to postnatal aneurysm progression in LDS.

Background: Loeys-Dietz syndrome, also known as Marfan syndrome type II, is a rare connective tissue disorder caused by dominant mutations in transforming growth factor-beta receptors (TGFBR1 and 2)., Case Presentation: We report a 7-year-old Japanese boy with Loeys-Dietz syndrome who carried a novel, de novo missense mutation in TGFBR2 (c.1142g > c, R381P). He showed dysmorphic faces and skeletal malformations that were typical in previous cases with Loeys-Dietz syndrome. The cardiac studies disclosed the presence of markedly dilated aortic root and patent ductus aorteriosus. The cranial magnetic resonance imaging (MRI) and angiography (MRA) detected the tortuous appearances of the bilateral middle cerebral and carotid arteries., Conclusion: This study depicts the systemic vascular phenotypes of a child with Loeys-Dietz syndrome that were caused by a novel heterozygous mutation of TGFR2. A large cohort with serial imaging studies for vascular phenotypes will be useful for delineating the genotype-phenotype correlations of Loeys-Dietz syndrome.

Background and Purpose: Dural ectasia is well recognized in Marfan syndrome (MFS) as one of the major diagnostic criteria, but the exact prevalence of dural ectasia is still unknown in Loeys-Dietz syndrome (LDS), which is a recently discovered connective tissue disease. In this study, we evaluated the prevalence of dural ectasia in LDS according by using qualitative and quantitative methods and compared our findings with those for with MFS and normal controls., Material and Methods: We retrospectively studied 10 LDS (6 males, 4 females, mean age 36.3 years) and 20 MFS cases (12 males, 8 females, mean age 37.1 years) and 20 controls (12 males, 8 females, mean age 36.1 years) both qualitatively and quantitatively using axial CT images and sagittal multi-planar reconstruction images of the lumbosacral region. For quantitative examination, we adopted two methods: method-1 (anteroposterior dural diameter of S1> L4) and method-2 (ratio of anteroposterior dural diameter/vertebral body diameter>cutoff values). The prevalence of dural ectasia among groups was compared by using Fisher's exact test and the Tukey-Kramer test., Results: In LDS patients, the qualitative method showed 40% of dural ectasia, the quantitative method-1 50%, and the method-2 70%. In MFS patients, the corresponding prevalences were 50%, 75%, and 85%, and in controls, 0%, 0%, and 5%. Both LDS and MFS had a significantly wider dura than controls., Conclusions: While the prevalence of dural ectasia varied depending on differences in qualitative and quantitative methods, LDS as well as MFS, showed, regardless of method, a higher prevalence of dural ectasia than controls. This finding should help the differentiation of LDS from controls.

Background: Loeys-Dietz syndrome (LDS) is a recently recognized connective tissue disorder (CTD) caused by mutations in transforming growth factor-beta receptor (TGFBR)1 and TGFBR2. Surgical outcomes of aortic repair in patients with LDS are poorly known., Methods: We enrolled 16 patients with TGFBR mutations identified by gene analysis in this study. Between 1993 and 2011, they underwent 41 aortic surgical procedures. Ten patients (group D: dissection group) underwent aortic repair for acute or chronic aortic dissection as a first surgical intervention, and 6 patients (group N: nondissection group) underwent surgical treatment for aortic root dilatation. The mean follow-up period was 103.7 ± 92.3 months (range, 2- 276 months)., Results: There were no in-hospital deaths. In group N, valve-sparing root replacement (VSRR) was performed in all patients. The residual aorta in 9 patients (90%) from group D required further repairs, 3 times on average. Moreover, in 4 patients (40%), the aorta was entirely replaced in serial procedures. In group N, aortic dissection occurred in only 1 patient (17%). The aortic event-free rates at 5 years were 40% in group D and 80% in group N, respectively (p = 0.819). One late death due to arrhythmia occurred 1 month after VSRR. The cumulative survival rates at 5 years were 100% in group D and 83% in group N, respectively (p = 0.197)., Conclusions: Surgical outcomes for patients with LDS were satisfactory. Once aortic dissection occurred, the aorta expanded rapidly, requiring further operations. Therefore, early surgical intervention may improve prognosis by preventing a fatal aortic event., (Copyright © 2012 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.)

Loeys-Dietz syndrome (LDS) is a rare autosomal-dominant connective tissue disorder caused by heterozygous mutations in the genes encoding transforming growth factor beta receptor 1 or 2 (TGFBR1 or TGFBR2). Although an association between LDS and osteoporosis has been reported, the skeletal phenotype regarding bone mass is not well characterized. Here, we report on two LDS patients with mutations in TGFBR2. Patient 1 was a 24-year-old man who had a total of three fractures involving the left radius, the left metacarpal, and the right femur. At the age of 14 years, lumbar spine areal bone mineral density Z-score was -4.0 and iliac bone histomorphometry showed elevated bone turnover (bone formation rate per bone surface: 91 µm³/µm²/year; age-matched control values 37 [10], mean [SD]) and mildly low trabecular bone volume per tissue volume (17.2%; age-matched control values 25.7 [5.3]). Bone mineralization density distribution (BMDD) in trabecular bone was increased (Ca(Peak) 22.70 wt% Ca; age-matched control values 21.66 [0.52]). Patient 2, a 17-year-old girl, suffered from diffuse bone pain but had not sustained fractures. At 14 years of age, her lumbar spine areal bone mineral density Z-score was -3.4. Iliac bone histomorphometry at that age confirmed low bone mass (bone volume to tissue volume 10.1%, same control values as above) and high bone turnover (bone formation rate per bone surface 70 µm³/µm²/year). BMDD in trabecular bone was significantly shifted toward increased mineralization (Ca(Peak) 22.36 wt% Ca). Thus, it appears that LDS can be associated with low bone mass and high bone turnover but increased matrix mineralization of trabecular bone., (© 2012 American Society for Bone and Mineral Research)

Purpose: Transforming growth factor beta receptor II (TGFBR2) gene mutations are associated with Marfan syndrome; however, the relationship between the mutations and clinical phenotypes are not clear., Methods: Genomic DNA from peripheral blood leukocytes of a Chinese proband with Marfan syndrome, five of the proband's relatives, and 100 unrelated Chinese control subjects were isolated and screened for fibrillin-1 (FBN1) and TGFBR2 gene mutations by direct sequencing, and a genotype-phenotype study was performed following a review of the literature on TGFBR2 mutations in the search area. Also, the structure of TGFBR2 protein before and after gene mutation was analyzed., Results: The results identified a novel missense TGFBR2 mutation p.V453E (c.1358T>A) in the proband and two relatives that was located in the F-helix in the kinase domain of TGFBR2. No such genetic change was observed in the unrelated controls. No FBN1 mutation was detected in any of the subjects. Genotype-phenotype analyses indicated that F-helix mutations are related to type 2 Marfan syndrome and Loeys-Dietz syndrome, and these mutations can lead to severe cardiovascular (93.8%) and skeletal (81.3%) lesions and minor ocular lesions (25%). Losartan treatment can slow-down the progression of aortic lesions., Conclusions: The findings extend the mutation spectrum of Marfan syndrome, and that mutations at the F-helix in the kinase domain of TGFBR2 may be associated with the development of severe cardiovascular and skeletal lesions and minor ocular lesions. These findings have implications for genetic testing, diagnosis, and treatment in individuals with transforming growth factor beta (TGF-β) signaling-related disorders.

Loeys-Dietz syndrome (LDS) is an inherited disorder that is characterized by the triad of arterial tortuosity and aneurysms, hypertelorism and a bifid uvula or cleft palate. The disease is caused by heterozygous mutations in the genes encoding transforming growth factor β receptors 1 and 2 (TGFBR1 and TGFBR2, respectively). However, studies of patients with LDS are limited in Korea. From June 2000 to December 2010, 13 patients (10 probands) diagnosed with LDS were enrolled. The multidisciplinary data of the patients were reviewed retrospectively. The frequency of each clinical manifestation in Korean patients with LDS was compared with Western populations as described in the report by Loeys et al. Twelve (92%) of the 13 LDS patients had arterial tortuosity, 9 (69%) patients had hypertelorism and 11 (85%) patients had bifid uvula or cleft palate. Mutations in either TGFBR1 or TGFBR2 were detected in nine probands (90%). Of the mutations, five novel mutations were detected; three in TGFBR2 and two in TGFBR1. Blue sclera and atrial septal defect were not observed in the Korean patients, and the frequency of blue sclera was significantly lower in our Korean population than previously-described Western population (0 vs 40%; P=0.005). Despite the restricted number of patients in our study, we identified five novel mutations in the TGFBR1 and TGFBR2 genes and, except for blue sclera, no differences in phenotype are apparent between Korean patients and Western patients.

Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder characterized by facial dysmorphism, cleft palate, dilation of the aortic arch, blood vessel tortuosity and a high risk of aortic dissection. It is caused by mutations in the transforming growth factor β-receptor 1 and 2 (TGFβ-R1 and TGFβ-R2) genes. Fibroblasts derived from 12 Loeys-Dietz syndrome patients, six with TGFB-R1 mutations and six with TGFB-R2 mutations, were analyzed using RT-PCR, biochemical assays, immunohistochemistry and electron microscopy for production of elastin, fibrillin 1, fibulin 1 and fibulin 4 and deposition of collagen type I. All LDS fibroblasts with TGFβ-R1 mutations demonstrated decreased expression of elastin and fibulin 1 genes and impaired deposition of elastic fibers. In contrast, fibroblasts with TGFβ-R2 mutations consistently demonstrated intracellular accumulation of collagen type I in the presence of otherwise normal elastic fiber production. Treatment of the cell cultures with dexamethasone induced remarkable upregulation in the expression of tropoelastin, fibulin 1- and fibulin 4-encoding mRNAs, leading to normalization of elastic fiber production in fibroblasts with TGFβ-R1 mutations. Treatment with dexamethasone also corrected the abnormal secretion of collagen type I from fibroblasts with TGFβ-R2 gene mutations. As the organogenesis-relevant elastic fiber production occurs exclusively in late fetal and early neonatal life, these findings may have implications for treatment in early life. Further studies are required to determine if dexamethasone treatment of fetuses prenatally diagnosed with LDS would prevent or alleviate the connective tissue and vascular defects seen in this syndrome.

We describe a boy with Loeys-Dietz syndrome (LDS) a genetic and recently described condition that affects connective tissues belonging to a group of Marfan-related disorders. Since there are only a few cases reported misdiagnosis may not be uncommon. Radiological findings in our patient include pectus excavatum, aortic root dilatation, diffuse dilatation of the intracerebral vessels and a Chiari I malformation. We describe the imaging findings, clinical presentation and diagnosis criteria of this entity.

We report on a 2-year-old Polish girl with typical manifestations of Loeys-Dietz syndrome (LDS), a rare genetic condition belonging to the group of Marfan-related disorders. The characteristic LDS symptoms observed in the girl included craniofacial dysmorphism (craniosynostosis, cleft palate, hypertelorism), arachnodactyly, camptodactyly, scoliosis, joint laxity, talipes equinovarus, translucent and hyperelastic skin, and umbilical hernia. Mild dilatation of the ascending aorta and tortuous course of the left internal carotid artery were recognized during her second year of life. Molecular genetic testing revealed a heterozygous missense mutation (c.1582C>T, p.R528C) in the transforming growth factor beta receptor II gene (TGFBR2). This mutation has been previously associated with LDS in 5 unrelated cases, and was never reported in patients with other Marfan-related disorders. Comparison of the phenotypes of our patient and these 5 individuals with c.1582C>T showed that only the hallmark triad of the syndrome - consisting of hypertelorism, aortic root dilatation/aneurysm, and cleft palate or bifid uvula - was present in all 6 cases. Interestingly, none of the 5 individuals who underwent psychological evaluation showed developmental delay. The pattern of all other LDS features showed interindividual variability. Our data support the recently reported observation that symptoms of LDS can develop at a very young age, making early diagnosis and management essential for these patients. This is the first report on a Polish infant with typical LDS symptoms caused by a TGFBR2 mutation.