Identification of a novel TGFBR1 mutation in a Loeys-Dietz syndrome type II patient with vascular Ehlers-Danlos syndrome phenotype

Transforming growth factor beta signaling and craniofacial development: modeling human diseases in zebrafish

Humans and other jawed vertebrates rely heavily on their craniofacial skeleton for eating, breathing, and communicating. As such, it is vital that the elements of the craniofacial skeleton develop properly during embryogenesis to ensure a high quality of life and evolutionary fitness. Indeed, craniofacial abnormalities, including cleft palate and craniosynostosis, represent some of the most common congenital abnormalities in newborns. Like many other organ systems, the development of the craniofacial skeleton is complex, relying on specification and migration of the neural crest, patterning of the pharyngeal arches, and morphogenesis of each skeletal element into its final form. These processes must be carefully coordinated and integrated. One way this is achieved is through the spatial and temporal deployment of cell signaling pathways. Recent studies conducted using the zebrafish model underscore the importance of the Transforming Growth Factor Beta (TGF-β) and Bone Morphogenetic Protein (BMP) pathways in craniofacial development. Although both pathways contain similar components, each pathway results in unique outcomes on a cellular level. In this review, we will cover studies conducted using zebrafish that show the necessity of these pathways in each stage of craniofacial development, starting with the induction of the neural crest, and ending with the morphogenesis of craniofacial elements. We will also cover human skeletal and craniofacial diseases and malformations caused by mutations in the components of these pathways (e.g., cleft palate, craniosynostosis, etc.) and the potential utility of zebrafish in studying the etiology of these diseases. We will also briefly cover the utility of the zebrafish model in joint development and biology and discuss the role of TGF-β/BMP signaling in these processes and the diseases that result from aberrancies in these pathways, including osteoarthritis and multiple synostoses syndrome. Overall, this review will demonstrate the critical roles of TGF-β/BMP signaling in craniofacial development and show the utility of the zebrafish model in development and disease.

Multiple Self-Healing Squamous Epithelioma (MSSE): A Digenic Trait Associated with Loss of Function Mutations in TGFBR1 and Variants at a Second Linked Locus on the Long Arm of Chromosome 9

MSSE (Ferguson-Smith disease) is a rare familial condition in which multiple skin tumors resembling squamous carcinomas invade locally and then regress spontaneously after several months, leaving disfiguring scars. We review evidence from haplotype studies in MSSE families with common ancestry that the condition is caused by loss of function mutations in TGFBR1 interacting with permissive variants at a second linked locus on the long arm of chromosome 9. The spectrum of TGFBR1 mutations in MSSE and the allelic disorder Loeys Dietz syndrome (characterized by developmental anomalies and thoracic aortic aneurysms) differ. Reports of patients with both MSSE and Loeys Dietz syndrome are consistent with variants at a second locus determining whether self-healing epitheliomas occur in patients with the loss of function mutations found in most MSSE patients or the missense mutations in the intracellular kinase domain of TGFBR1 that characterize Loeys Dietz syndrome.

Application of the 2017 criteria for vascular Ehlers-Danlos syndrome in 50 patients ascertained according to the Villefranche nosology

Vascular Ehlers-Danlos syndrome (vEDS) is a rare inherited connective tissue disorder due to heterozygous pathogenic COL3A1 variants. Arterial, intestinal, and/or uterine fragility is the disease hallmark and results in reduced life expectancy. The clinical diagnosis is not always straightforward and patients' selection for molecular confirmation depends on the characteristics of applied criteria, that is, the Villefranche criteria (in use until 2017) and their revision according to the new EDS nosology. Herein, we reassessed the clinical features of 50 molecularly proven vEDS patients, diagnosed according to the Villefranche nosology between 2000 and 2016, using the 2017 classification in order to explore its clinical application. Our findings indicate that the Villefranche criteria were particularly valuable for symptomatic patients, even if with a limited specificity. Our study also suggests that the revised vEDS criteria, although expected to be more specific, might have a poorer accuracy, principally in terms of sensitivity. Both sets of criteria are less effective in presymptomatic young patients, especially in the absence of a clear-cut family history. For these patients, the careful evaluation of the cutaneous, articular, and dysmorphic features and, above all, genetic testing remain crucial to set-up proper follow-up and surveillance before catastrophic vascular and intestinal events.

Transforming growth factor-β and inflammation in vascular (type IV) Ehlers-Danlos syndrome

BACKGROUND

Vascular Ehlers-Danlos syndrome (VEDS) causes reduced life expectancy because of arterial dissections/rupture and hollow organ rupture. Although the causative gene, COL3A1, was identified >20 years ago, there has been limited progress in understanding the disease mechanisms or identifying treatments.

METHODS AND RESULTS

We studied inflammatory and transforming growth factor-β (TGF-β) signaling biomarkers in plasma and from dermal fibroblasts from patients with VEDS. Analyses were done in terms of clinical disease severity, genotype-phenotype correlations, and body composition and fat deposition alterations. VEDS subjects had increased circulating TGF-β1, TGF-β2, monocyte chemotactic protein-1, C-reactive protein, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and leptin and decreased interleukin-8 versus controls. VEDS dermal fibroblasts secreted more TGF-β2, whereas downstream canonical/noncanonical TGF-β signaling was not different. Patients with COL3A1 exon skipping mutations had higher plasma intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, and VEDS probands had abnormally high plasma C-reactive protein versus affected patients identified through family members before any disease manifestations. Patients with VEDS had higher mean platelet volumes, suggesting increased platelet turnover because of ongoing vascular damage, as well as increased regional truncal adiposity.

CONCLUSIONS

These findings suggest that VEDS is a systemic disease with a major inflammatory component. C-reactive protein is linked to disease state and may be a disease activity marker. No changes in downstream TGF-β signaling and increased platelet turnover suggest that chronic vascular damage may partially explain increased plasma TGF-β1. Finally, we found a novel role for dysregulated TGF-β2, as well as adipocyte dysfunction, as demonstrated through reduced interleukin-8 and elevated leptin in VEDS.

A patient with Loeys-Dietz syndrome treated with chemoradiotherapy for an oropharyngeal carcinoma

We present the first published case of a patient with Loeys-Dietz syndrome (LDS) who was treated with radical chemoradiotherapy for an oropharyngeal carcinoma. In view of this newly recognised connective tissue disease, the uncertainty of severe toxicity from chemoradiotherapy to treat a potentially curative cancer posed a management challenge. The patient was treated with chemoradiotherapy and remains well with no evidence of recurrence at 3 years. Furthermore, we have observed minimal late effects secondary to chemoradiotherapy at 3 years following the completion of treatment suggesting that the underlying pathogenesis of LDS may provide an interesting human model to further elucidate the complex interactions of transforming growth factor β1 (TGF-β1) and tissue fibrosis secondary to chemoradiotherapy. A review of LDS as well as the association of TGF-β1 expression and tissue fibrosis is presented.

Characterization of large genomic deletions in the FBN1 gene using multiplex ligation-dependent probe amplification

BACKGROUND

Connective tissue diseases characterized by aortic aneurysm, such as Marfan syndrome, Loeys-Dietz syndrome and Ehlers Danlos syndrome type IV are heterogeneous and despite overlapping phenotypes, the natural history, clinical manifestations and interventional course for each diagnosis can be quite unique. The majority of mutations involved in the etiology of these disorders are missense and nonsense mutations. However, large deletions and duplications undetected by sequencing may be implicated in their pathogenesis, and may explain the apparent lack of genotype-phenotype correlation in a subset of patients. The objective of this study was to search for large pathogenic deletions and/or duplications in the FBN1, TGFβR1, and TGFβR2 genes using multiplex-ligation dependent probe amplification (MLPA) in patients with aortopathy, in whom no mutations in the FBN1, TGFβR1, and TGFβR2 genes were identified by sequencing.

METHODS

The study included 14 patients from 11 unrelated families with aortic aneurysm. Of those, six patients (including 3 first-degree relatives), fulfilled the revised Ghent criteria for Marfan syndrome, and eight had predominantly aortic aneurysm/dilatation with variable skeletal and craniofacial involvement. MLPA for FBN1, TGFβR1, and TGFβR2 was carried out in all patients. A 385 K chromosome 15 specific array was used in two patients with a deletion of the entire FBN1 in order to define its size and boundaries.

RESULTS

We identified two novel large deletions in the FBN1 gene in four patients of two unrelated families who met clinical diagnostic criteria for Marfan syndrome. One patient was found to have a FBN1 deletion encompassing exons 1-5. The other three patients had a 542 Kb deletion spanning the whole FBN1 gene and five additional genes (SLC24A5, MYEF2, CTXN2, SLC12A1, DUT) in the chromosome 15.

CONCLUSIONS

Our findings expand the number of large FBN1 deletions, and emphasize the importance of screening for large genomic deletions in connective tissue disorders featuring aortopathies, especially for those with classic Marfan phenotype.

Ehlers Danlos Syndrome Type IV and pregnancy

INTRODUCTION

A case report is presented of a 23-year-old patient who was diagnosed with Ehlers Danlos syndrome (EDS) Type IV (vascular type) in the 23rd week of her second pregnancy. EDS Type IV has one of the highest mortality rates for pregnant women of any condition with significant morbidity if the mother survives.

DISCUSSION

Current literature is presented and supports the necessity for close monitoring of mother and child in a specialist unit with involvement of a multi-disciplinary team. There is no agreed consensus on the mode or timing of delivery but recent literature is supportive of delivery by caesarean section at 32 weeks.

CONCLUSION

This case report demonstrates a successful outcome for both mother and child with a planned delivery at 34 weeks by caesarean section and emphasises the importance of strategic planning for complicated deliveries and the effectiveness of good communication networks. Patients with EDS Type IV should be counselled about the potential risks for both themselves and the child to enable them to make informed decisions about their obstetric care.

Multiple self-healing squamous epithelioma is caused by a disease-specific spectrum of mutations in TGFBR1

Multiple self-healing squamous epithelioma (MSSE), also known as Ferguson-Smith disease (FSD), is an autosomal-dominant skin cancer condition characterized by multiple squamous-carcinoma-like locally invasive skin tumors that grow rapidly for a few weeks before spontaneously regressing, leaving scars. High-throughput genomic sequencing of a conservative estimate (24.2 Mb) of the disease locus on chromosome 9 using exon array capture identified independent mutations in TGFBR1 in three unrelated families. Subsequent dideoxy sequencing of TGFBR1 identified 11 distinct monoallelic mutations in 18 affected families, firmly establishing TGFBR1 as the causative gene. The nature of the sequence variants, which include mutations in the extracellular ligand-binding domain and a series of truncating mutations in the kinase domain, indicates a clear genotype-phenotype correlation between loss-of-function TGFBR1 mutations and MSSE. This distinguishes MSSE from the Marfan syndrome-related disorders in which missense mutations in TGFBR1 lead to developmental defects with vascular involvement but no reported predisposition to cancer.

Dexamethasone normalizes aberrant elastic fiber production and collagen 1 secretion by Loeys-Dietz syndrome fibroblasts: a possible treatment?

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.

Loeys-Dietz syndrome type I and type II: clinical findings and novel mutations in two Italian patients

Background

Loeys-Dietz syndrome (LDS) is a rare autosomal dominant disorder showing the involvement of cutaneous, cardiovascular, craniofacial, and skeletal systems. In particular, LDS patients show arterial tortuosity with widespread vascular aneurysm and dissection, and have a high risk of aortic dissection or rupture at an early age and at aortic diameters that ordinarily are not predictive of these events. Recently, LDS has been subdivided in LDS type I (LDSI) and type II (LDSII) on the basis of the presence or the absence of cranio-facial involvement, respectively. Furthermore, LDSII patients display at least two of the major signs of vascular Ehlers-Danlos syndrome. LDS is caused by mutations in the transforming growth factor (TGF) beta-receptor I (TGFBR1) and II (TGFBR2) genes. The aim of this study was the clinical and molecular characterization of two LDS patients.

Methods

The exons and intronic flanking regions of TGFBR1 and TGFBR2 genes were amplified and sequence analysis was performed.

Results

Patient 1 was a boy showing dysmorphic signs, blue sclerae, high-arched palate, bifid uvula; skeletal system involvement, joint hypermobility, velvety and translucent skin, aortic root dilatation, tortuosity and elongation of the carotid arteries. These signs are consistent with an LDSI phenotype. The sequencing analysis disclosed the novel TGFBR1 p.Asp351Gly de novo mutation falling in the kinase domain of the receptor. Patient 2 was an adult woman showing ascending aorta aneurysm, with vascular complications following surgery intervention. Velvety and translucent skin, venous varicosities and wrist dislocation were present. These signs are consistent with an LDSII phenotype. In this patient and in her daughter, TGFBR2 genotyping disclosed in the kinase domain of the protein the novel p.Ile510Ser missense mutation.

Conclusion

We report two novel mutations in the TGFBR1 and TGFBR2 genes in two patients affected with LDS and showing marked phenotypic variability. Due to the difficulties in the clinical approach to a TGFBR-related disease, among patients with vascular involvement, with or without aortic root dilatation and LDS cardinal features, genotyping is mandatory to clarify the diagnosis, and to assess the management, prognosis, and counselling issues.