Homozygous deletion of exons 2–7 within TGFB3 gene in a child with severe Loeys‐Dietz syndrome and Marfan‐like features

We describe a patient with palatal abnormalities—cleft palate and bifid uvula; distinctive facial features—long and triangular face, large ears and nose, thin lips and dental crowding; musculoskeletal abnormalities—severe scoliosis, joint laxity, long digits, flat feet, decreased muscle mass, and diminished muscle strength; and cardiac features—a dilatated ascending aorta at the level of Valsalva sinuses and a patent foramen ovale. Sequence analysis and deletion/duplication testing for a panel of genes involved in connective tissue disorders revealed the presence of a novel homozygous deletion of exons 2–7 in TGFB3 gene. Heterozygous pathogenic mutations in TGFB3 have been associated with Loeys‐Dietz syndrome 5 (LDS5) and Arrhythmogenic Right Ventricular Dysplasia type 1. Here, we report the first case of a homozygous TGFB3 variant associated with a severe LDS5 and Marfan‐like presentation.     

Aortic arch geometry predicts outcome in patients with Loeys–Dietz syndrome independent of the causative gene

This study aimed to investigate the potential association between imaging features and cardiovascular outcomes in patients with Loeys–Dietz syndrome (LDS). We performed a retrospective cohort study of 36 patients with LDS and described cardiovascular events and imaging data. We observed different clinical courses in patients with LDS, irrespective of the causative gene. Angular or elongated aortic arch geometry correlated with aortic dissection (R = .39, p = .02), occurrence of the first cardiovascular event before 45 years of age (R = .36, p = .03), and the number of operations (R = 0.47, p = .004), but not with age (R = ?.05, p = .79) or the causative gene (R = ?0.04, p = .79). Relative absences of cardiovascular events at ages 20, 40, and 60 were 100, 75, and 56%, respectively, in patients with “romanesque” aortic arches, and 74, 39, and 21%, respectively, in patients with “gothic” and “elongated” aortic arches (p = .03). Angular or elongated aortic arch geometry is associated with early‐onset of disease and a worse cardiovascular outcome in LDS patients. Large multicenter studies are warranted to elucidate the impact of aortic arch morphology evaluation in clinical practice.     

Ectopia lentis as the presenting and primary feature in Marfan syndrome

Marfan syndrome (MFS) is a multisystem connective tissue disorder with primary involvement of the ocular, cardiovascular, and skeletal systems. We report on eight patients, all presenting initially with bilateral ectopia lentis (EL) during early childhood. These individuals did not have systemic manifestations of MFS, and did not fulfill the revised Ghent diagnostic criteria. However, all patients had demonstratable, disease-causing missense mutations in the FBN1 gene. Based on molecular results, cardiovascular imaging was recommended and led to the identification of mild aortic root changes in seven of the eight patients. The remaining patient had mitral valve prolapse with a normal appearing thoracic aorta. The findings presented in this paper validate the necessity of FBN1 gene testing in all individuals presenting with isolated EL. As we observed, these individuals are at increased risk of cardiovascular complications. Furthermore, we also noted that the majority of our patient cohort's mutations occurred in the 5' portion of the FBN1 gene, and were found to affect highly conserved cysteine residues, which may indicate a possible genotype-phenotype correlation. We conclude that in patients with isolated features of EL, FBN1 mutation analysis is necessary to aid in providing prompt diagnosis, and to identify patients at risk for potentially life-threatening complications. Additionally, knowledge of the type and location of an FBN1 mutation may be useful in providing further clinical correlation regarding phenotypic progression and appropriate medical management.     

Applying massive parallel sequencing to molecular diagnosis of Marfan and Loeys‐Dietz syndromes

The Marfan (MFS) and Loeys‐Dietz (LDS) syndromes are caused by mutations in the fibrillin‐1 (FBN1) and Transforming Growth Factor Beta Receptor 1 and 2 (TGFBR1 and TGFBR2) genes, respectively. With the current conventional mutation screening technologies, analysis of this set of genes is time consuming and expensive. We have tailored a cost‐effective and reliable mutation discovery strategy using multiplex PCR followed by Next Generation Sequencing (NGS). In a first stage, genomic DNA from five MFS or LDS patient samples with previously identified mutations and/or polymorphisms in FBN1 and TGFBR1 and 2 were analyzed and revealed all expected variants. In a second stage, we validated the technique on 87 samples from MFS patients fulfilling the Ghent criteria. This resulted in the identification of 75 FBN1 mutations, of which 67 were unique. Subsequent Multiplex Ligation‐dependent Probe Amplification (MLPA) analysis of the remaining negative samples identified four large deletions/insertions. Finally, Sanger sequencing identified a missense mutation in FBN1 exon 1 that was not included in the NGS workflow. In total, there was an overall mutation identification rate of 92%, which is in agreement with data published previously. We conclude that multiplex PCR of all coding exons of FBN1 and TGFBR1/2 followed by NGS analysis and MLPA is a robust strategy for time‐ and cost‐effective identification of mutations. Hum Mutat 32:1–10, 2011. © 2011 Wiley‐Liss, Inc.     

Phenotypic variability and diffuse arterial lesions in a family with Loeys–Dietz syndrome type 4

Syndromic thoracic aortic aneurysm and dissection (TAAD) can suggest Marfan, vascular Ehlers–Danlos or Loeys–Dietz (LDS) syndromes. Several of the TGFβ‐pathway‐related genes predispose to different types of LDS. Heterozygous loss‐of‐function variations in TGFβ2 have been shown to be responsible for a novel form of syndromic TAAD associated with an impairment of the mitral valve and cerebrovascular disease called Loeys–Dietz syndrome type 4 (LDS4). We report the clinical characterization of a LDS4 French family with sudden deaths and diffuse vascular lesions, caused by a frameshift mutation in TGFβ2 gene: c.[995del]; p.(Leu332TrpfsTer27). Clinical characteristics include aneurysm of aortic sinus, skeletal and cutaneous features compatible with a syndromic form of TAAD (joint hypermobility, scoliosis, and easy bruises), intracranial aneurysms and rare mitral valve involvement. Iliac aneurysms, systemic medium caliber arteries dissections, and mild developmental delay were present in the family, and have not been described in LDS4. Phenotypic variability was also an important finding, including absence of clinical vascular events at advanced age in one case. Our data expand the phenotype of LDS4: we confirm that TGFβ2 mutations are responsible for true LDS syndrome with non‐specific features of connective tissue disorders and diffuse vascular lesions. Adapted vascular follow up and prevention has to be proposed for these patients.     

Ectopia lentis and aortic root dilatation in congenital contractural arachnodactyly

Congenital contractural arachnodactyly (CCA) was described by Beals and Hecht as an autosomal dominant disorder distinct from Marfan syndrome and comprising joint contractures, arachnodactyly, scoliosis, and a distinct “crumpled ear” deformity. While the disorder is similar to Marfan syndrome, it was split from it due to the distinct physical appearance of the patients and, more importantly, the lack of heart and eye findings. Since the original report, several CCA patients have been found to have mitral valve prolapse, structural cardiac anomalies, and occasionally aortic root dilatations similar to those seen in Marfan syndrome. We report on a patient with CCA with bilateral ectopia lentis and aortic root dilatation. Our review of the literature of CCA showed that serial echo-cardiography and careful eye examinations have not become a standard of medical practice in this condition. Partly this may be due to a lack of documented cases of CCA having severe ectopia lentis and cardiac complications. This patient underscores the need for periodic eye and echocardiographic evaluations of all CCA patients.     

Adults with Loeys–Dietz syndrome and vascular Ehlers–Danlos syndrome: A cross‐sectional study of health burden perspectives

The aim is to study adults with vascular Ehlers–Danlos syndrome (vEDS) and Loeys–Dietz syndrome (LDS) with regard to sociodemographic characteristics, perceived vascular‐ and multi‐organ symptom burdens, and health services utilization. This is a cross‐sectional study. In 2018, a postal questionnaire was sent to 71 individuals with genetically verified LDS types 1–4 or vEDS, age ≥ 18 years, recruited through a National Resource Centre for Rare Disorders in Norway. Eighteen patients with vEDS and 34 patients with LDS subtypes 1‐4 participated, the response rate was 74%. Median age was 43.5 (range 18‐68) years, and 58% were women. Median age at diagnosis was 34 years (range: 6–63). Severe vascular‐ and multi‐organ symptom burdens were found, and chronic pain was reported by 79%. Most respondents (87%) had cardiovascular surveillance visits, 58% yearly or more often, and still 29% had no antihypertensive medications. Three quarters communicated diagnosis‐related concerns with their general practitioner. A considerable group (31%) had left work before retirement age. Healthcare professionals should be aware of the spectrum of health burden in adults with vEDS and LDS. A verification of the diagnosis is crucial to counseling, including medical follow‐up, education, and work, and advices on precaution and life style decisions.     

Dural ectasia in Loeys–Dietz syndrome: comprehensive study of 30 patients with a TGFBR1 or TGFBR2 mutation

The purpose of this study was to assess the frequency, severity, and clinical associations of dural ectasia (DE) in Loeys–Dietz syndrome (LDS). Database analysis of three German metropolitan regions identified 30 patients with LDS and TGFBR1 mutation in 6 and a TGFBR2 mutation in 24 individuals (17 men; mean age: 31 ± 19 years), as well as 60 age and sex‐matched control patients with Marfan syndrome carrying a FBN1 mutation. DE was present in 22 patients with LDS (73%), and it related to skeletal score points (p = 0.008), non‐skeletal score points (p < 0.001), and to the presence of ≥7 systemic score points (p = 0.010). Similarly, the severity of DE was related to body height (p = 0.010) and non‐skeletal score points (p = 0.004). Frequency (p = 0.131) and severity of DE (p = 0.567) was similar in LDS and Marfan syndrome. DE is a manifestation of LDS that occurs with similar frequency and severity as in Marfan syndrome. Severity of DE may serve as a marker of the overall connective tissue disease severity. LDS may be considered in patients with DE.     

A mutation update on the LDS‐associated genes TGFB2/3 and SMAD2/3

The Loeys–Dietz syndrome (LDS) is a connective tissue disorder affecting the cardiovascular, skeletal, and ocular system. Most typically, LDS patients present with aortic aneurysms and arterial tortuosity, hypertelorism, and bifid/broad uvula or cleft palate. Initially, mutations in transforming growth factor‐β (TGF‐β) receptors (TGFBR1 and TGFBR2) were described to cause LDS, hereby leading to impaired TGF‐β signaling. More recently, TGF‐β ligands, TGFB2 and TGFB3, as well as intracellular downstream effectors of the TGF‐β pathway, SMAD2 and SMAD3, were shown to be involved in LDS. This emphasizes the role of disturbed TGF‐β signaling in LDS pathogenesis. Since most literature so far has focused on TGFBR1/2, we provide a comprehensive review on the known and some novel TGFB2/3 and SMAD2/3 mutations. For TGFB2 and SMAD3, the clinical manifestations, both of the patients previously described in the literature and our newly reported patients, are summarized in detail. This clearly indicates that LDS concerns a disorder with a broad phenotypical spectrum that is still emerging as more patients will be identified. All mutations described here are present in the corresponding Leiden Open Variant Database.     

Performant Mutation Identification Using Targeted Next‐Generation Sequencing of 14 Thoracic Aortic Aneurysm Genes

At least 14 causative genes have been identified for both syndromic and nonsyndromic forms of thoracic aortic aneurysm/dissection (TAA), an important cause of death in the industrialized world. Molecular confirmation of the diagnosis is increasingly important for gene‐tailored patient management but consecutive, conventional molecular TAA gene screening is expensive and labor‐intensive. To circumvent these problems, we developed a TAA gene panel for next‐generation sequencing of 14 TAA genes. After validation, we applied the assay to 100 Marfan patients. We identified 90 FBN1 mutations, 44 of which were novel. In addition, Multiplex ligation‐dependent probe amplification identified large deletions in six of the remaining samples, whereas false‐negative results were excluded by Sanger sequencing of FBN1, TGFBR1, and TGFBR2 in the last four samples. Subsequently, we screened 55 syndromic and nonsyndromic TAA patients. We identified causal mutations in 15 patients (27%), one in each of the six following genes: ACTA2, COL3A1, TGFBR1, MYLK, SMAD3, SLC2A10 (homozygous), two in NOTCH1, and seven in FBN1. We conclude that our approach for TAA genetic testing overcomes the intrinsic hurdles of consecutive Sanger sequencing of all candidate genes and provides a powerful tool for the elaboration of clinical phenotypes assigned to different genes.     

TGFBR1 and TGFBR2 mutations in patients with features of Marfan syndrome and Loeys-Dietz syndrome

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder characterized by manifestations in the cardiovascular, skeletal, ocular, and other organ systems. MFS type1 (MFS1) is caused by mutations in the gene encoding fibrillin (FBN1). Recently, the transforming growth factor-beta receptor-2 gene, TGFBR2, has been shown to be associated with a second type of this disorder with typically mild or absent ocular involvement (MFS type 2; MFS2). Several point mutations were found in the highly conserved serine/threonine kinase domain of TGFBR2. Mutations in both TGFBR1 and TGFBR2 are associated with Loeys-Dietz aortic aneurysm syndrome (LDS). We searched for TGFBR1 and TGFBR2 mutations in 41 unrelated patients fulfilling the diagnostic criteria of Ghent nosology or with the tentative diagnosis of Marfan syndrome, in whom mutations in the FBN1 coding region were not identified. In TGFBR1, two mutations and two polymorphisms were detected. In TGFBR2, five mutations and six polymorphisms were identified. Reexamination of patients with a TGFBR1 or TGFBR2 mutation revealed extensive clinical overlap between patients with MFS1, MFS2, and LDS.     

Detection of 15 novel mutations in 52 children from 40 families with the Marfan or Loeys–Dietz syndrome and phenotype–genotype correlations

We report about 52 pediatric patients of 40 different families with confirmed Marfan syndrome (MFS) in 49 patients and Loeys–Dietz syndrome (LDS) in 3 patients. We found 39 different mutations, 15 of them being novel. Phenotype–genotype correlation in the 49 MFS patients showed that the majority of patients carrying mutations in exons 1–21 had ectopic lens (80%). Patients having mutations in exons 23–32 had a higher probability of aortic root dilation, in 50% even above a z score of 3. We found three children with neonatal MFS form, two of them with novel mutations. Of the three LDS patients, only one presented with the typical phenotype of LDS type 1.