A genotype to phenotype relationship of exudative vitreoretinopathy in Loeys–Dietz syndrome due to a pathogenic variant in TGFBR2

Background: Pathogenic variants in TGFBR1, TGFBR2 and SMAD3 genes cause Loeys-Dietz syndrome, and pathogenic variants in FBN1 cause Marfan syndrome. Despite their similar phenotypes, both syndromes may have different cardiovascular outcomes. Methods: Three expert centers performed a case-matched comparison of cardiovascular outcomes. The Loeys-Dietz group comprised 43 men and 40 women with a mean age of 34 ± 18 years. Twenty-six individuals had pathogenic variants in TGFBR1, 40 in TGFBR2, and 17 in SMAD3. For case-matched comparison we used 83 age and sex-frequency matched individuals with Marfan syndrome. Results: In Loeys-Dietz compared to Marfan syndrome, a patent ductus arteriosus (p = 0.014) was more prevalent, the craniofacial score was higher (p < 0.001), the systemic score lower (p < 0.001), and mitral valve prolapse less frequent (p = 0.003). Mean survival for Loeys-Dietz and Marfan syndrome was similar (75 ± 3 versus 73 ± 2 years; p = 0.811). Cardiovascular outcome was comparable between Loeys-Dietz and Marfan syndrome, including mean freedom from proximal aortic surgery (53 ± 4 versus 48 ± 3 years; p = 0.589), distal aortic repair (72 ± 3 versus 67 ± 2 years; p = 0.777), mitral valve surgery (75 ± 4 versus 65 ± 3 years; p = 0.108), and reintervention (20 ± 3 versus 14 ± 2 years; p = 0.112). In Loeys-Dietz syndrome, lower age at initial presentation predicted proximal aortic surgery (HR = 0.748; p < 0.001), where receiver operating characteristic analysis identified ≤33.5 years with increased risk. In addition, increased aortic sinus diameters (HR = 6.502; p = 0.001), and higher systemic score points at least marginally (HR = 1.175; p = 0.065) related to proximal aortic surgery in Loeys-Dietz syndrome. Conclusions: Cardiovascular outcome of Loeys-Dietz syndrome was comparable to Marfan syndrome, but the severity of systemic manifestations was a predictor of proximal aortic surgery.

Background: Familial exudative vitreoretinopathy (FEVR) is an inherited retinal disorder with high genetic heterogeneity, and it is characterized by a defect in the development of the retinal vascular system. Loeys-Dietz syndrome (LDS) is an autosomal dominant systemic connective tissue disorder that is caused by mutations in the genes related to transforming growth factor signaling systems including the TGFBR2 gene. Two earlier studies reported that patients with LDS from mutations in the TGFBR2 gene were associated with FEVR-like retinal phenotype. The purpose of this study was to determine the characteristics of a case of FEVR without systemic abnormalities who had a mutation in the TGFBR2 gene. Materials and Methods: The clinical appearances and surgical outcomes were determined from the medical records. Genetic analysis was performed by whole exome sequencing. Results: A 15-year-old boy was diagnosed with FEVR by the appearance of the peripheral retina of both eyes and a retinal detachment in the left eye. Whole exome sequencing revealed a heterozygous deletion mutation in the TGFBR2 gene. A de novo mutation was confirmed by examining the family members. No systemic abnormalities were detected in the patient including those associated with LDS. Conclusions: FEVR can be associated with a TGFBR2 mutation without showing signs of LDS.

Aortic aneurysm and aortic dissection can have a major impact on the life expectancy of Marfan syndrome (MFS) or Loeys-Dietz syndrome (LDS) patients. Although obesity can influence the development of aortic complications, evidence on whether obesity influences the development of aortic aneurysm or dissection in MFS and LDS is limited. The aim of the present study was to elucidate the relationship between aortic size and body composition, assessed by modern bioelectrical impedance analysis (BIA) in MFS/LDS-patients. In this exploratory cross-sectional study in MFS or LDS patients, enrolled between June 2020 and May 2022, 34 patients received modern BIA and magnetic resonance imaging (MRI) (n=32) or computed tomography (CT) imaging (n=2) of the entire aorta. A P value of <0.05 was considered significant. Fifty-one patients (66% female; mean age: 37.7±11.7; range, 17-68 years) with MFS or LDS were enrolled; 34 patients, 27 with MFS and 7 with LDS, underwent aortic MRI or CT scanning. The mean aortic length was 503.7±58.7 mm, and the mean thoracic aortic length and abdominal aortic length were 351.5±52.4 and 152.2±27.4 mm, respectively. The aortic bulb and the ascending aorta were measured only in the non-surgically repaired patients. Fifteen MFS (88.2%) and two LDS (40.0%) patients had an aortic aneurysm. In these, the aortic bulb tended to be larger in MFS than in LDS patients [42.6×41.9×41.2 vs. 37.8×37.4×36.8 mm; P=0.07 (-1.1; 9.1); P=0.07 (-1.2; 8.4); P=0.07 (-1.5; 7.9)]. BIA revealed mean body fat levels of 31.6%±8.7% (range, 9.5-53.5%), indicating that 18 patients (52.9%) were obese. There was a significant correlation between body fat content and thoracic aortic length (R=-0.377; P=0.02), muscle mass and total aortic length (R=0.359; P=0.03), thoracic aortic length (R=0.399; P=0.02), extracellular mass (ECM), and total aortic length (R=0.354; P=0.04), and connective tissue and aortic diameters at the aortic arch (R=0.511; P=0.002), aortic isthmus (R=0.565; P<0.001), and abdominal aorta (R=0.486; P=0.004). Older age was correlated with wider aortic arch, isthmus, and abdominal aorta. Male patients had a longer aorta. While a slender habitus is commonly known for MFS and LDS patients, our data show that many MFS and LDS patients (especially female) do not fit this phenotypic characteristic and are obese, which is associated with a more severe aortic phenotype. This topic should be included in the clinical assessment of affected MFS and LDS patients, in addition to measurement of the aortic diameters. Physicians should systematically screen MFS and LDS patients for obesity, educate them about the potential risk of resulting aortic complications, and encourage them to adopt a healthy lifestyle, that includes (mild) exercise and a balanced diet.

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.

Loeys–Dietz syndrome (LDS) is a rare connective tissue genetic disorder that is caused by a pathogenic variant in genes of transforming growth factor (TGF) beta receptor 1 (TGFBR1), TGFBR2, mothers against decapentaplegic homolog 2 (SMAD2), SMAD3, TGFB2, or TGFB3. It is characterized by aggressive vascular pathology, aneurysms, arterial tortuosity, bifid uvula, hypertelorism, and cleft palate. Here we present a 42-year-old female patient with LDS. The patient underwent rapidly progressing artery aneurysms and life-threatening aortic dissection. Spontaneous fracture of the first metatarsal bone was noted in her medical record. Physical examination revealed a delayed wound healing on her left abdomen. Considering these clinical manifestations, we speculated that there was a genetic defect in the connective tissue, which provides strength and flexibility to structures such as bones, skins, ligaments, and blood vessels. Thus, whole exome sequencing (WES) was performed on the proband and revealed a heterozygous missense pathogenic variant (c.1613T > C/p.Val538Ala) in TGFBR2, which was a de novo variant in the proband as confirmed by the segregation analysis in parental samples. Although this variant was discovered and associated with the phenotype of LDS previously, the pathogenicity of the variant had not been confirmed by cellular functional assay yet. To further validate the effects of the variant in vitro, we assessed the canonical TGF-β signaling pathway in mutant cells. Our results showed that the p.Val538Ala variant significantly decreased TGF-β-induced gene transcription and the phosphorylation of Smad2, which were consistent with other pathogenic variants of TGFBR2. In conclusion, this study demonstrates that the p.Val538Ala pathogenic variant in TGFBR2 leads to aberrant TGF-β signaling and LDS in this patient.

The transforming growth factor beta receptor 1 (TGFBR1) gene is associated with two distinct clinical presentations, Multiple Self-Healing Squamous Epithelioma (MSSE) also known as Ferguson-Smith syndrome and Loeys-Dietz syndrome. MSSE is characterized by development of multiple self-healing skin tumours that may affect any part of the body. Spontaneous resolution may take several months leaving pitted scars. Most pathogenic variants in MSSE patients are truncating variants distributed throughout the gene or missense variants in the receptor domain of TGFBR1. Missense variants in the kinase domain of TGFBR1 cause LDS which is a connective tissue disorder associated with increased risk of aortic and arterial aneurysms and dissection. There are two reports in the literature of patients with both MSSE and LDS phenotype and a missense variant in the kinase domain of TGFBR1. The patient reported here has MSSE with at least 20 skin tumours (four with perineural invasion) and features of LDS. The patient harbors a heterozygous missense pathogenic variant c.1043G>A p.(Cyst348Tyr) in TGFBR1 which has previously been associated with LDS but not MSSE. This report is consistent with the hypothesis that a variant in a second locus determines whether skin tumours develop in a patient with missense variant in the kinase domain of TGFBR1 associated with LDS. It also highlights the association of more histologically aggressive keratocanthomas associated with perineural invasion in MSSE.

Loeys-Dietz syndrome (LDS) is a connective tissue disease caused by mutations in the genes encoding the transforming growth factor-beta receptor (TGFBR). LDS is associated with aneurysms or dissections of the aorta similar to Marfan syndrome (MFS) as well as arterial tortuosity and aneurysms in the peripheral arteries. The purpose of this study was to evaluate the arterial diseases of LDS to differentiate it from MFS. A total of 10 LDS patients with an identified mutation in TGFBR (6 male, 4 female; mean age 36.3 years) and 20 MFS patients with an identified mutation in fibrilin-1 who were age- and sex-matched to the LDS subjects (12 male, 8 female; mean age 37.1 years) were reviewed. The prevalence of vertebral arterial tortuosity (VAT) and peripheral aneurysm (PAN) was studied using computed tomography angiography. In all, 9 of the 10 LDS patients had VAT, and five PANs were observed in 3 patients. In contrast, 8 (40%) of the MFS patients had VAT, and 1 patient had a PAN. LDS had a higher prevalence of VAT (P = 0.017) by Fisher's exact test. The VAT was highly prevalent among LDS patients. Thus, the presence of VAT has the potential to differentiate LDS from MFS.

Gremlin-1 Is Overexpressed in Endothelial Cells of Patients with Loeys-Dietz Syndrome Due to Dysregulation of TGF-β Signalling,

Loeys-Dietz Syndrome (LDS) is a rare connective tissue disorder with an autosomal dominant pattern of inheritance, linked to heterozygous mutations in six genes from the transforming growth factor beta receptor complex. The classical syndrome characteristics include aortic aneurisms with generalized arterial tortuosity, hypertelorism and cleft palate or bifid/broad uvula. LDS is also associated with a wide range of skeletal, craniofacial, cutaneous and ocular abnormalities, as well as allergic, atopic and inflammatory diseases. Common oral findings include high arched and/or narrow palate, enamel defects and class II skeletal malocclusion. Dental management of patients with LDS is complex and includes approaches to prevent medical complications, as well as considerations for safe delivery of dental care. The purpose of this report, reviews the literature related to LDS oral manifestations as well as to describe the comprehensive dental management of an adolescent patient with LDS and discuss the challenges that dental practitioners may face when providing treatment for these patients. LDS is a newly described syndrome and the literature reviewing its oral manifestations is limited. Patients are reported to have lower oral health-related quality of life as a result of tooth sensitivity and malocclusions. Dental management is compounded by the complexity of medical factors that should be taken into consideration for the safe delivery of care. The presented case is an example of the challenges that dental practitioners may face when providing treatment for LDS patients.

BACKGROUND: Loeys-Dietz syndrome (LDS) is a rare autosomal dominant disorder of connective tissue caused by mutations in the genes encoding receptor subunits for TGFβ, TGFBR1 and TGFBR2. It is characterized by arterial aneurysms and dissections, skeletal abnormalities, joint laxity and craniofacial abnormalities. There is an increased risk of immunologic diseases including allergic and eosinophilic gastrointestinal disorders, as well as inflammatory bowel disease (IBD). TGF-β signaling plays an important role in regulating mucosal immune responses likely leading to increased propensity for development of IBD. This case highlights a rare presentation of LDS, with symptoms of IBD presenting in advance of cardiac symptoms, leading to diagnosis of this rare connective tissue disorder. CASE: A 14 yo Male presented with 1 year of intermittent bloody stools, diarrhea and fatigue. Physical exam was only positive for a bifid uvula and marfanoid body habitus. Laboratory testing showed microcytic anemia, elevated C-reactive protein, erythrocyte sedimentation rate, and hypoalbuminemia. Stool tests were negative for infectious causes of diarrhea. Esophagogastroduodenoscopy and colonoscopy showed gross findings of duodenal ulcer and mucosal ulceration throughout the colon. Histology showed chronic focal active duodenitis with intramucosal granuloma, and chronic active pancolitis. No eosinophils were observed. Findings were thought to be consistent with diagnosis of IBD, so patient was initially treated with Mesalamine and Prednisone. After treatment failure, therapy was switched to infliximab plus oral methotrexate, and responded well, clinically. Approximately 6 months after diagnosis of IBD, the patient developed chest pain, tachycardia, and shortness of breath. Due to new elevation of CRP and ESR, there was a suspicion for myocarditis. Echocardiogram, however, showed bicuspid aortic valve with dilated aortic root. Given this finding, the cardiologists suspected a collagen disorder and subsequently started patient on Losartan. After being seen by Genetics, a next generation sequencing panel demonstrated mutation of the TGFBR2 (p.C61Y) gene. He was diagnosed with LDS. Three years after diagnosis, patient has remained in deep remission of his IBD with combination of infliximab and methotrexate. One year after diagnosis of LDS, the patient’s aortic root dilation reached critical limits and he successfully underwent ascending aortic graft and aortic root replacement with On-X 25 valve. He tolerated this procedure well and remains on lifelong anticoagulation therapy. DISCUSSION: It is thought that patients with LDS are 10 times more likely to have IBD than the general population. However, the occurrence of non-eosinophilic chronic IBD in patients with LDS has been reported but has been poorly documented. Typical cases of LDS described in literature present with eosinophilic gastrointestinal disorders, food allergies and rarely IBD. Typically, cardiac and skeletal disorders precede the GI manifestations. Our case is remarkable in that the patient first diagnosed with IBD and then later presented with cardiac symptoms finally leading to diagnosis of LDS. Currently, there is no established protocol for the evaluation and management of IBD in LDS patients. This case highlights life-threatening aortic or cardiovascular conditions linked with LDS. As such, a low index of suspicion is needed when managing IBD in patients with features suggestive of LDS.

Loeys-Dietz syndrome (LDS) is a rare connective tissue disorder. In LDS patients with normal arch morphology, whether the arch should be prophylactically replaced at the time of proximal aortic replacement remains unknown. We evaluated the risk of long-term arch complications in genetically confirmed LDS patients who underwent proximal ascending aortic replacement. We retrospectively reviewed the records of patients with LDS who have been followed at our institution between 1994 and 2020. Patients were only included if whole exome genetic testing confirmed a mutation in an LDS-causing gene (TGFBR1, TGFBR2, SMAD3, TGFB2, or TGFB3). Mutations were categorized as pathogenic, benign, or of unknown significance. We collected demographic information, aortic dimensions, comorbidities, mortality, and operative course from patients' charts. Descriptive statistics and freedom from reoperation plots were generated. Of the 18 patients with a mutation in an LDS-causing gene, 15 had known pathogenic variants, two had mutations of unknown significance, and one had a benign genetic variant. For the 15 patients with confirmed pathogenic variants of LDS the median follow-up duration was 5 years (interquartile range [IQR]: 4-8). Eleven patients underwent ascending aortic replacements (AAR) ± aortic valve replacement. Two patients required an additional operation; one required arch and staged elephant trunk for a dissection 18 years post-AAR and the other patient required an isolated descending aortic replacement for dissection 5 years post-AAR. Among patients who underwent surgery, the median ascending aortic diameter at intervention was 5.0 cm (IQR: 4.3-5.3). There was no surgical or late follow-up mortality observed for any of the 18 patients in the study. LDS patients who underwent proximal aortic replacement appeared to have low long-term risk of arch complications. While our study is somewhat limited by its sample size and follow-up duration, it suggests that routine prophylactic total arch replacement may not be warranted in LDS patients with nonaneurysmal aortic arches.

Funding Acknowledgements ISCIII PI14/0106 and PI17/00381, La Marató de TV3 (20151330), Eur FP7/People 267128 and CIBERCV BACKGROUND Genetic syndromic aortic diseases are rare, with Marfan syndrome (MFS) being the most common. However, less is known of Loeys-Dietz syndrome (LDS) which has much lower prevalence and presumed worse prognosis. Increased aortic stiffness in MFS has been previously described but no studies have evaluated aortic biomechanics in LDS. Pulse wave velocity (PWV) is the gold standard measure for arterial stiffness and can be quantified by 4D flow MRI. We aim to evaluate regional aortic PWV by 4D flow MRI in LDS compared to MFS and healthy volunteers. METHODS Sixteen LDS patients with a pathogenic mutation, 76 MFS and 49 healthy volunteers were prospectively and consecutively included. No patient had previous aortic dissection or surgery. All underwent a 4D flow MRI study in a 1.5 T clinical scanner. Ascending (AAo) and descending (DAo) aorta PWV were computed using wavelet analysis of the systolic upslope for transit time calculation (Figure). Statistical comparison was made with non-parametric analysis to account for the non-normality of data and multivariate analysis was evaluated separately for AAo and DAo PWV. RESULTS Ascending and descending aortic PWV revealed stiffer aortas in LDS patients than in healthy volunteers, even after adjustment for diameter of sinus of Valsalva (SoV) and sex. Conversely, no differences in aortic stiffness were found between LDS and MFS patients (Table). CONCLUSIONS Abnormally high regional aortic stiffness was observed in LDS patients when compared with controls. The severity of increased regional aortic stiffness was found similar to the one affecting MFS patients. Table Controls (N = 49) LDS (N = 16) MFS (N = 76) LDS vs. HV LDS vs. MFN Parameter Unadjusted p-value Adjusted p-value Unadjusted p-value Adjusted p-value Age [years] 39 ± 12 39 ± 16 36 ± 12 0.903 0.599 Men 32 (65%) 6 (37%) 34 (45%) 0.079 0.782 Weight [kg] 72 ± 11 69 ± 13 74 ± 16 0.288 0.194 Height [cm] 172 ± 8 172 ±12 181 ± 11 0.834 0.008 Systolic BP [mmHg] 126 ± 18 125 ± 14 127 ± 17 0.957 0.523 Diastolic BP [mmHg] 70 ± 11 77 ± 6 75 ± 12 0.011 0.318 SoV diameter [mm] 30.6 ± 3.9 35.4 ± 4.6 38.1 ± 5.9 0.001 0.060 AAo diameter [mm] 27.7 ± 3.8 29,0 ± 5.0 29.7 ± 5.4 0.458 0.579 DAo diameter [mm] 20.0 ± 2.0 21.3 ± 3.6 22.9 ± 3.8 0.546 0.124 AAo PWV [m/s] 5.2 ± 1.9 7.6 ± 2.4 7.3 ± 2.8 0.001 0.050* 0.534 NS DAo PWV [m/s] 7.1 ± 2.2 9.4 ± 2.6 10.7 ± 4.6 0.003 0.025** 0.493 NS Abstract P372 Figure

ABSTRACTBackground: Loeys-Dietz syndrome (LDS) is a connective tissue disorder that has phenotypic overlap with Marfan syndrome. In LDS, the aortic root dissections can be more aggressive and occur at a younger age than Marfan syndrome.Materials and Methods: Review of two cases.Results: A 7-year old boy with history of LDS was found to have a vitreous hemorrhage in the right eye. Further examination showed findings of Familial Exudative Vitreoretinopathy (FEVR). Both eyes were found to have peripheral non-perfusion and neovascularization. A non-related 25-month-old boy with no molecularly confirmed connective tissue disorder was found to have bilateral peripheral non-perfusion and bilateral tractional retinal detachments. The boy was clinically diagnosed with Larsen syndrome, Ehlers-Danlos syndrome kyphoscoliotic form, and Marfan syndrome before presentation. The FEVR lead to consideration of LDS that was molecularly confirmed. Consequently, he was monitored for aortic root dilation.Conclusion: FEVR findings may lead to diagnosis of LDS and patients with LDS may present with proliferative retinopathy.

Familial exudative vitreoretinopathy (FEVR) is an inherited blinding disorder of the retinal vascular system. Although mutations in three genes (LRP5, FZD4, and NDP) are known to cause FEVR, these account for only a fraction of FEVR cases. The proteins encoded by these FEVR genes form part of a signaling complex that activates the Norrin-beta-catenin signaling pathway. Recently, through a large-scale reverse genetic screen in mice, Junge and colleagues identified an additional member of this signaling complex, Tspan12. Here, we report that mutations in TSPAN12 also cause autosomal-dominant FEVR. We describe seven mutations identified in a cohort of 70 FEVR patients in whom we had already excluded the known FEVR genes. This study provides further evidence for the importance of the Norrin-beta-catenin signaling pathway in the development of the retinal vasculature and also indicates that more FEVR genes remain to be identified.

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.