Janneke Timmermans

Mutations in SMAD3 cause a syndromic form of aortic aneurysms and dissections with early-onset osteoarthritis

Thoracic aortic aneurysms and dissections are a main feature of connective tissue disorders, such as Marfan syndrome and Loeys-Dietz syndrome. We delineated a new syndrome presenting with aneurysms, dissections and tortuosity throughout the arterial tree in association with mild craniofacial features and skeletal and cutaneous anomalies. In contrast with other aneurysm syndromes, most of these affected individuals presented with early-onset osteoarthritis. We mapped the genetic locus to chromosome 15q22.2–24.2 and show that the disease is caused by mutations in SMAD3. This gene encodes a member of the TGF-β pathway that is essential for TGF-β signal transmission. SMAD3 mutations lead to increased aortic expression of several key players in the TGF-β pathway, including SMAD3. Molecular diagnosis will allow early and reliable identification of cases and relatives at risk for major cardiovascular complications. Our findings endorse the TGF-β pathway as the primary pharmacological target for the development of new treatments for aortic aneurysms and osteoarthritis.

Loss-of-function mutations in TGFB2 cause a syndromic presentation of thoracic aortic aneurysm

Loeys-Dietz syndrome (LDS) associates with a tissue signature for high transforming growth factor (TGF)-β signaling but is often caused by heterozygous mutations in genes encoding positive effectors of TGF-β signaling, including either subunit of the TGF-β receptor or SMAD3, thereby engendering controversy regarding the mechanism of disease. Here, we report heterozygous mutations or deletions in the gene encoding the TGF-β2 ligand for a phenotype within the LDS spectrum and show upregulation of TGF-β signaling in aortic tissue from affected individuals. Furthermore, haploinsufficient Tgfb2+/− mice have aortic root aneurysm and biochemical evidence of increased canonical and noncanonical TGF-β signaling. Mice that harbor both a mutant Marfan syndrome (MFS) allele (Fbn1C1039G/+) and Tgfb2 haploinsufficiency show increased TGF-β signaling and phenotypic worsening in association with normalization of TGF-β2 expression and high expression of TGF-β1. Taken together, these data support the hypothesis that compensatory autocrine and/or paracrine events contribute to the pathogenesis of TGF-β–mediated vasculopathies.

Losartan reduces aortic dilatation rate in adults with Marfan syndrome: a randomized controlled trial

AIM Patients with Marfan syndrome have an increased risk of life-threatening aortic complications, mostly preceded by aortic dilatation. Treatment with losartan, an angiotensin-II receptor-1 blocker, may reduce aortic dilatation rate in Marfan patients. METHODS AND RESULTS In this multicentre, open-label, randomized controlled trial with blinded assessments, we compared losartan treatment with no additional treatment in operated and unoperated adults with Marfan syndrome. The primary endpoint was aortic dilatation rate at any predefined aortic level after 3 years of follow-up, as determined by magnetic resonance imaging. A total of 233 participants (47% female) underwent randomization to either losartan (n = 116) or no additional treatment (n = 117). Aortic root dilatation rate after 3.1 ± 0.4 years of follow-up was significantly lower in the losartan group than in controls (0.77 ± 1.36 vs. 1.35 ± 1.55 mm, P = 0.014). Aortic dilatation rate in the trajectory beyond the aortic root was not significantly reduced by losartan. In patients with prior aortic root replacement, aortic arch dilatation rate was significantly lower in the losartan group when compared with the control group (0.50 ± 1.26 vs. 1.01 ± 1.31 mm, P = 0.033). No significant differences in separate clinical endpoints or the composite endpoint (aortic dissection, elective aortic surgery, cardiovascular death) between the groups could be demonstrated. CONCLUSION In adult Marfan patients, losartan treatment reduces aortic root dilatation rate. After aortic root replacement, losartan treatment reduces dilatation rate of the aortic arch.

Phenotypic spectrum of the SMAD3-related aneurysms–osteoarthritis syndrome

Background Aneurysms–osteoarthritis syndrome (AOS) is a new autosomal dominant syndromic form of thoracic aortic aneurysms and dissections characterised by the presence of arterial aneurysms and tortuosity, mild craniofacial, skeletal and cutaneous anomalies, and early-onset osteoarthritis. AOS is caused by mutations in the SMAD3 gene. Methods A cohort of 393 patients with aneurysms without mutation in FBN1, TGFBR1 and TGFBR2 was screened for mutations in SMAD3. The patients originated from The Netherlands, Belgium, Switzerland and USA. The clinical phenotype in a total of 45 patients from eight different AOS families with eight different SMAD3 mutations is described. In all patients with a SMAD3 mutation, clinical records were reviewed and extensive genetic, cardiovascular and orthopaedic examinations were performed. Results Five novel SMAD3 mutations (one nonsense, two missense and two frame-shift mutations) were identified in five new AOS families. A follow-up description of the three families with a SMAD3 mutation previously described by the authors was included. In the majority of patients, early-onset joint abnormalities, including osteoarthritis and osteochondritis dissecans, were the initial symptom for which medical advice was sought. Cardiovascular abnormalities were present in almost 90% of patients, and involved mainly aortic aneurysms and dissections. Aneurysms and tortuosity were found in the aorta and other arteries throughout the body, including intracranial arteries. Of the patients who first presented with joint abnormalities, 20% died suddenly from aortic dissection. The presence of mild craniofacial abnormalities including hypertelorism and abnormal uvula may aid the recognition of this syndrome. Conclusion The authors provide further insight into the phenotype of AOS with SMAD3 mutations, and present recommendations for a clinical work-up.

Mutations in a TGF-β Ligand, TGFB3, Cause Syndromic Aortic Aneurysms and Dissections

Background Aneurysms affecting the aorta are a common condition associated with high mortality as a result of aortic dissection or rupture. Investigations of the pathogenic mechanisms involved in syndromic types of thoracic aortic aneurysms, such as Marfan and Loeys-Dietz syndromes, have revealed an important contribution of disturbed transforming growth factor (TGF)-β signaling. Objectives This study sought to discover a novel gene causing syndromic aortic aneurysms in order to unravel the underlying pathogenesis. Methods We combined genome-wide linkage analysis, exome sequencing, and candidate gene Sanger sequencing in a total of 470 index cases with thoracic aortic aneurysms. Extensive cardiological examination, including physical examination, electrocardiography, and transthoracic echocardiography was performed. In adults, imaging of the entire aorta using computed tomography or magnetic resonance imaging was done. Results Here, we report on 43 patients from 11 families with syndromic presentations of aortic aneurysms caused by TGFB3 mutations. We demonstrate that TGFB3 mutations are associated with significant cardiovascular involvement, including thoracic/abdominal aortic aneurysm and dissection, and mitral valve disease. Other systemic features overlap clinically with Loeys-Dietz, Shprintzen-Goldberg, and Marfan syndromes, including cleft palate, bifid uvula, skeletal overgrowth, cervical spine instability and clubfoot deformity. In line with previous observations in aortic wall tissues of patients with mutations in effectors of TGF-β signaling (TGFBR1/2, SMAD3, and TGFB2), we confirm a paradoxical up-regulation of both canonical and noncanonical TGF-β signaling in association with up-regulation of the expression of TGF-β ligands. Conclusions Our findings emphasize the broad clinical variability associated with TGFB3 mutations and highlight the importance of early recognition of the disease because of high cardiovascular risk.

Aggressive Cardiovascular Phenotype of Aneurysms-Osteoarthritis Syndrome Caused by Pathogenic SMAD3 Variants

OBJECTIVES The purpose of this study was describe the cardiovascular phenotype of the aneurysms-osteoarthritis syndrome (AOS) and to provide clinical recommendations. BACKGROUND AOS, caused by pathogenic SMAD3 variants, is a recently described autosomal dominant syndrome characterized by aneurysms and arterial tortuosity in combination with osteoarthritis. METHODS AOS patients in participating centers underwent extensive cardiovascular evaluation, including imaging, arterial stiffness measurements, and biochemical studies. RESULTS We included 44 AOS patients from 7 families with pathogenic SMAD3 variants (mean age: 42 ± 17 years). In 71%, an aortic root aneurysm was found. In 33%, aneurysms in other arteries in the thorax and abdomen were diagnosed, and in 48%, arterial tortuosity was diagnosed. In 16 patients, cerebrovascular imaging was performed, and cerebrovascular abnormalities were detected in 56% of them. Fifteen deaths occurred at a mean age of 54 ± 15 years. The main cause of death was aortic dissection (9 of 15; 60%), which occurred at mildly increased aortic diameters (range: 40 to 63 mm). Furthermore, cardiac abnormalities were diagnosed, such as congenital heart defects (6%), mitral valve abnormalities (51%), left ventricular hypertrophy (19%), and atrial fibrillation (22%). N-terminal brain natriuretic peptide (NT-proBNP) was significantly higher in AOS patients compared with matched controls (p < 0.001). Aortic pulse wave velocity was high-normal (9.2 ± 2.2 m/s), indicating increased aortic stiffness, which strongly correlated with NT-proBNP (r = 0.731, p = 0.005). CONCLUSIONS AOS predisposes patients to aggressive and widespread cardiovascular disease and is associated with high mortality. Dissections can occur at relatively mildly increased aortic diameters; therefore, early elective repair of the ascending aorta should be considered. Moreover, cerebrovascular abnormalities were encountered in most patients.

Beneficial Outcome of Losartan Therapy Depends on Type of FBN1 Mutation in Marfan Syndrome

Background—It has been shown that losartan reduces aortic dilatation in patients with Marfan syndrome. However, treatment response is highly variable. This study investigates losartan effectiveness in genetically classified subgroups. Methods and Results—In this predefined substudy of COMPARE, Marfan patients were randomized to daily receive losartan 100 mg or no losartan. Aortic root dimensions were measured by MRI at baseline and after 3 years. FBN1 mutations were classified based on fibrillin-1 protein effect into (1) haploinsufficiency, decreased amount of normal fibrillin-1, or (2) dominant negative, normal fibrillin-1 abundance with mutant fibrillin-1 incorporated in the matrix. A pathogenic FBN1 mutation was found in 117 patients, of whom 79 patients were positive for a dominant negative mutation (67.5%) and 38 for a mutation causing haploinsufficiency (32.5%). Baseline characteristics between treatment groups were similar. Overall, losartan significantly reduced aortic root dilatation rate (no losartan, 1.3±1.5 mm/3 years, n=59 versus losartan, 0.8±1.4 mm/3 years, n=58; P=0.009). However, losartan reduced only aortic root dilatation rate in haploinsufficient patients (no losartan, 1.8±1.5 mm/3 years, n=21 versus losartan 0.5±0.8 mm/3 years, n=17; P=0.001) and not in dominant negative patients (no losartan, 1.2±1.7 mm/3 years, n=38 versus losartan 0.8±1.3 mm/3 years, n=41; P=0.197). Conclusions—Marfan patients with haploinsufficient FBN1 mutations seem to be more responsive to losartan therapy for inhibition of aortic root dilatation rate compared with dominant negative patients. Additional treatment strategies are needed in Marfan patients with dominant negative FBN1 mutations. Clinical Trial Registration—http://www.trialregister.nl/trialreg/index.asp; Unique Identifier: NTR1423.

Standardized Multidisciplinary Evaluation Yields Significant Previously Undiagnosed Morbidity in Adult Women with Turner Syndrome

CONTEXT Besides short stature and gonadal dysgenesis, Turner syndrome (TS) is associated with various abnormalities. Adults with TS have a reduced life expectancy, mainly related to structural abnormalities of the heart and aorta, and an increased risk of atherosclerosis. OBJECTIVE Our objective was to investigate the yield of an initial standardized multidisciplinary screening in adult TS patients. DESIGN AND SETTING This was an observational study at a multidisciplinary care unit for adult women with TS. PARTICIPANTS Participants were adult women with TS (n = 150). Mean age was 31.0 ± 10.4 yr, with 47% karyotype 45,X. INTERVENTIONS All women were consulted by an endocrinologist, a gynecologist, a cardiologist, an otorhinolaryngologist, and when indicated, a psychologist. The screening included magnetic resonance imaging of the heart and aorta, echocardiography, electrocardiogram, dual-energy x-ray absorptiometry, renal ultrasound, audiogram, and laboratory investigations according to international expert recommendations. MAIN OUTCOME MEASURES New diagnoses and prevalence of TS-associated morbidity were evaluated. RESULTS Thirty percent of patients currently lacked medical follow-up, and 15% lacked estrogen replacement therapy in the recent last years. The following disorders were newly diagnosed: bicuspid aortic valve (n = 13), coarctation of the aorta (n = 9), elongation of the transverse aortic arch (n = 27), dilation of the aorta (n = 34), osteoporosis (n = 8), osteopenia (n = 56), renal abnormalities (n = 7), subclinical hypothyroidism (n = 33), celiac disease (n = 3), glucose intolerance (n = 12), dyslipidemia (n = 52), hypertension (n = 39), and hearing loss warranting a hearing aid (n = 8). Psychological consultation was needed in 23 cases. CONCLUSIONS Standardized multidisciplinary evaluation of adult women with TS as advocated by expert opinion is effective and identifies significant morbidity. Girls with TS benefit from a careful transition to ongoing adult medical care.

Circulating transforming growth factor-β as a prognostic biomarker in Marfan syndrome

BACKGROUND Patients with Marfan syndrome (MFS) are at risk for cardiovascular disease. Marfan associated mutations in the FBN1 gene lead to increased transforming growth factor-β (TGF-β) activation. The aim of this study was to investigate the role of plasma TGF-β as a biomarker for progressive aortic root dilatation and dissection. METHODS Plasma TGF-β level and aortic root diameter by means of echocardiography were assessed in 99 MFS patients. After 38 months of follow-up measurement of the aortic root was repeated and individual aortic root growth curves were constructed. Clinical events were evaluated. The primary composite endpoint was defined as aortic dissection and prophylactic aortic root replacement. RESULTS TGF-β levels were higher in MFS patients as compared to healthy controls (109 pg/ml versus 54 pg/ml, p<0.001). Higher plasma TGF-β levels correlated with larger aortic root dimensions (r=0.26, p=0.027), previous aortic root surgery (161 pg/ml versus 88 pg/ml, p=0.007) and faster aortic root growth rate (r=0.42, p<0.001). During 38 months of follow-up, 17 events were observed (four type B dissections and 13 aortic root replacements). Patients with TGF-β levels above 140 pg/ml had a 6.5 times higher risk of experiencing the composite endpoint compared to patients with TGF-β levels below 140 pg/ml (95% CI: 2.1 to 20.1, p=0.001) with 65% sensitivity and 78% specificity. CONCLUSION Elevated TGF-β level in patients with Marfan syndrome is correlated with larger aortic root diameters and faster aortic root growth. Level of plasma TGF-β predicts cardiovascular events and might serve as a prognostic biomarker in MFS.

Critical appraisal of the revised Ghent criteria for diagnosis of Marfan syndrome

Radonic T, de Witte P, Groenink M, de Bruin‐Bon RACM, Timmermans J, Scholte AJH, van den Berg MP, Baars MJH, van Tintelen JP, Kempers M, Zwinderman AH, Mulder BJM. Critical appraisal of the revised Ghent criteria for diagnosis of Marfan syndrome.