Arterial tortuosity syndrome in two Italian paediatric patients

Tortuosity in non-atherosclerotic vascular diseases is associated with age, arterial aneurysms, and hypertension

BACKGROUND

Increased arterial tortuosity has been associated with various cardiovascular complications. However, the extent and role of arterial tortuosity in non-atherosclerotic vascular diseases remain to be fully elucidated. This study aimed to assess arterial tortuosity index (ATI) in patients with non-atherosclerotic vascular diseases and the associated factors.

METHODS

This is a retrospective analysis of patients with non-atherosclerotic vascular diseases referred to the Malformation and Rare Vascular Disease Center at the University Hospital in Lausanne (Switzerland). Computed tomography angiography (CTA) images performed between October 2010 and April 2022 were retrieved and the aortic tortuosity index (ATI) was calculated. Patients were classified based on diagnosis into the following groups: arterial dissection & aneurysm, arteritis & autoimmune disease, hereditary connective tissue diseases, and fibromuscular dysplasia (FMD). Univariate and multivariate logistic regression analysis was used to determine potentially relevant predictors of aortic tortuosity.

RESULTS

The mean age upon computed tomography angiography (CTA) was 46.8 (standard deviation [SD] 14.6) years and 59.1% of the patients were female. Mean ATI was higher in patients over 60 years old (1.27), in those with arterial aneurysms (mean: 1.11), and in those diagnosed with hypertension (mean: 1.13). When only patients over 60 years old were considered, those diagnosed with connective tissue diseases had the highest ATI. At multivariate regression analysis, increasing age (p < 0.05), presence of arterial aneurysms (p < 0.05), and hypertension (p < 0.05) were independently associated with ATI.

CONCLUSIONS

The ATI may be a promising tool in diagnostic evaluation, cardiovascular risk stratification, medical or surgical management, and prognostic assessment in several non-atherosclerotic vascular conditions. Further studies with longitudinal design and larger cohorts are needed to validate the role of ATI in the full spectrum of vascular diseases.

Arterial Tortuosity Syndrome: An Ascorbate Compartmentalization Disorder?

Significance: Cardiovascular disorders are the most important cause of morbidity and mortality in the Western world. Monogenic developmental disorders of the heart and vessels are highly valuable to study the physiological and pathological processes in cardiovascular system homeostasis. The arterial tortuosity syndrome (ATS) is a rare, autosomal recessive connective tissue disorder showing lengthening, tortuosity, and stenosis of the large arteries, with a propensity for aneurysm formation. In histopathology, it associates with fragmentation and disorganization of elastic fibers in several tissues, including the arterial wall. ATS is caused by pathogenic variants in SLC2A10 encoding the facilitative glucose transporter (GLUT)10. Critical Issues: Although several hypotheses have been forwarded, the molecular mechanisms linking disrupted GLUT10 activity with arterial malformations are largely unknown. Recent Advances: The vascular and systemic manifestations and natural history of ATS patients have been largely delineated. GLUT10 was identified as an intracellular transporter of dehydroascorbic acid, which contributes to collagen and elastin cross-linking in the endoplasmic reticulum, redox homeostasis in the mitochondria, and global and gene-specific methylation/hydroxymethylation affecting epigenetic regulation in the nucleus. We revise here the current knowledge on ATS and the role of GLUT10 within the compartmentalization of ascorbate in physiological and diseased states. Future Directions: Centralization of clinical, treatment, and outcome data will enable better management for ATS patients. Establishment of representative animal disease models could facilitate the study of pathomechanisms underlying ATS. This might be relevant for other forms of vascular dysplasia, such as isolated aneurysm formation, hypertensive vasculopathy, and neovascularization. Antioxid. Redox Signal. 34, 875-889.

Comprehensive in silico Study of GLUT10: Prediction of Possible Substrate Binding Sites and Interacting Molecules

OBJECTIVES

The Arterial Tortuosity Syndrome (ATS) is an autosomal recessive connective tissue disorder, mainly characterized by tortuosity and stenosis of the arteries with a propensity towards aneurysm formation and dissection. It is caused by mutations in the SLC2A10 gene that encodes the facilitative glucose transporter GLUT10. The molecules transported by and interacting with GLUT10 have still not been unambiguously identified. Hence, the study attempts to identify both the substrate binding site of GLUT10 and the molecules interacting with this site.

METHODS

As High-resolution X-ray crystallographic structure of GLUT10 was not available, 3D homology model of GLUT10 in open conformation was constructed. Further, molecular docking and bioinformatics investigation were employed.

RESULTS AND DISCUSSION

Blind docking of nine reported potential in vitro substrates with this 3D homology model revealed that substrate binding site is possibly made with PRO531, GLU507, GLU437, TRP432, ALA506, LEU519, LEU505, LEU433, GLN525, GLN510, LYS372, LYS373, SER520, SER124, SER533, SER504, SER436 amino acid residues. Virtual screening of all metabolites from the Human Serum Metabolome Database and muscle metabolites from Human Metabolite Database (HMDB) against the GLUT10 revealed possible substrates and interacting molecules for GLUT10, which were found to be involved directly or partially in ATS progression or different arterial disorders. Reported mutation screening revealed that a highly emergent point mutation (c. 1309G>A, p. Glu437Lys) is located in the predicted substrate binding site region.

CONCLUSION

Virtual screening expands the possibility to explore more compounds that can interact with GLUT10 and may aid in understanding the mechanisms leading to ATS.

Clinical Variability in Two Macedonian Families with Arterial Tortuosity Syndrome

Arterial tortuosity syndrome (ATS) is a rare autosomal recessive disorder caused by mutations in the solute carrier family 2 member 10 (SLC2A10) gene encoding a glucose/ascorbic acid transporter. The clinical features of ATS are mild-to-severe tortuosity of the large and medium arteries throughout the body, accompanied by dysmorphisms and joint laxity. Vascular changes in different parts of the body lead to stenosis and/or aneurysms requiring difficult surgical procedures. Here we present two new patients with ATS from two unrelated families. Patient 1 presented at 10 years of age with headache and typical physical appearance, delicate skeleton, large visible pulsation of the carotid arteries in the neck, and joint laxity. On computed tomography (CT) angiography she had severe tortuosity of the aortal branches and cerebral arteries, but no significant tortuosity of the pulmonary arteries. Two cousins of the girl carried the same homozygous c.254T>C, p.(Leu85Pro) mutation in SLC2A10, however, they additionally had a severe involvement of the pulmonary vessels. Patient 2 was a 9-year-old girl diagnosed with severe tortuosity and stenosis of the pulmonary arteries and progressive myocardiopathy. Her physical appearance was very similar to Patient 1, except that she also had growth retardation. After long-term follow-up by cardiologists, she underwent cardiac surgery abroad, with an unfavorable outcome. Homozygosity for the c.685C>T, p.(Arg229*) mutation in the SLC2A10 gene was detected. Consanguinity was disclosed within both families. Our findings confirm the intrafamilial phenotype variability of ATS. A novel finding is the severe tortuosity of cerebral arteries causing migraine that has not been described before in a child with ATS.

Variants of genes encoding collagens and matrix metalloproteinase system increased the risk of aortic dissection

Aortic dissection (AD) is a devastating, heterogeneous condition of aorta. The homeostasis between collagens and matrix metalloproteases (MMPs)/tissue inhibitors of MMPs (TIMPs) system in the extracellular matrix plays an important role for structure and functions of aorta. However, our knowledge on association between variants of genes in this system and pathogenesis of AD is very limited. We analyzed all yet known coding human genes of collagens (45 genes), MMPs/TIMPs (27 genes) in 702 sporadic AD patients and in 163 matched healthy controls, by using massively targeted next-generation and Sanger sequencing. To define the pathogenesis of potential disease-causing candidate genes, we performed transcriptome sequencing and pedigree co-segregation analysis in some genes and generated Col5a2 knockout rats. We identified 257 pathogenic or likely pathogenic variants which involved 88.89% (64/72) genes in collagens-MMPs/TIMPs system and accounted for 31.05% (218/702) sporadic AD patients. In them, 84.86% patients (185/218) carried one variant, 12.84% two variants and 2.30% more than two variants. Importantly, we identified 52 novel probably pathogenic loss-of-function (LOF) variants (20 nonsense, 16 frameshift, 14 splice sites, one stop-loss, one initiation codon) in 11.06% (50/452) AD patients, which were absent in 163 controls (P=2.5×10^-5). Transcriptome sequencing revealed that identified variants induced dyshomeostasis in expression of collagens-TIMPs/MMPs systems. The Col5a2 ^-/- rats manifested growth retardation and aortic dysplasia. Our study provides a first comprehensive map of genetic alterations in collagens-MMPs/TIMPs system in sporadic AD patients and suggests that variants of these genes contribute largely to AD pathogenesis.

GLUT10 deficiency leads to oxidative stress and non-canonical αvβ3 integrin-mediated TGFβ signalling associated with extracellular matrix disarray in arterial tortuosity syndrome skin fibroblasts

Arterial tortuosity syndrome (ATS) is an autosomal recessive connective tissue disorder caused by loss-of-function mutations in SLC2A10, which encodes facilitative glucose transporter 10 (GLUT10). The role of GLUT10 in ATS pathogenesis remains an enigma, and the transported metabolite(s), i.e. glucose and/or dehydroascorbic acid, have not been clearly elucidated. To discern the molecular mechanisms underlying the ATS aetiology, we performed gene expression profiling and biochemical studies on skin fibroblasts. Transcriptome analyses revealed the dysregulation of several genes involved in TGFβ signalling and extracellular matrix (ECM) homeostasis as well as the perturbation of specific pathways that control both the cell energy balance and the oxidative stress response. Biochemical and functional studies showed a marked increase in ROS-induced lipid peroxidation sustained by altered PPARγ function, which contributes to the redox imbalance and the compensatory antioxidant activity of ALDH1A1. ATS fibroblasts also showed activation of a non-canonical TGFβ signalling due to TGFBRI disorganization, the upregulation of TGFBRII and connective tissue growth factor, and the activation of the αvβ3 integrin transduction pathway, which involves p125FAK, p60Src and p38 MAPK. Stable GLUT10 expression in patients' fibroblasts normalized redox homeostasis and PPARγ activity, rescued canonical TGFβ signalling and induced partial ECM re-organization. These data add new insights into the ATS dysregulated biological pathways and definition of the pathomechanisms involved in this disorder.

Arterial Tortuosity Syndrome: homozygosity for two novel and one recurrent SLC2A10 missense mutations in three families with severe cardiopulmonary complications in infancy and a literature review

Background

Arterial Tortuosity Syndrome (ATS) is a very rare autosomal recessive connective tissue disorder (CTD) characterized by tortuosity and elongation of the large- and medium-sized arteries and a propensity for aneurysm formation and vascular dissection. During infancy, children frequently present the involvement of the pulmonary arteries (elongation, tortuosity, stenosis) with dyspnea and cyanosis. Other CTD signs of ATS are dysmorphisms, abdominal hernias, joint hypermobility, skeletal abnormalities, and keratoconus. ATS is typically described as a severe disease with high rate of mortality due to major cardiovascular malformations. ATS is caused by mutations in the SLC2A10 gene, which encodes the facilitative glucose transporter 10 (GLUT10). Approximately 100 ATS patients have been described, and 21 causal mutations have been identified in the SLC2A10 gene.

Case presentation

We describe the clinical findings and molecular characterization of three new ATS families, which provide insight into the clinical phenotype of the disorder; furthermore, we expand the allelic repertoire of SLC2A10 by identifying two novel mutations. We also review the ATS patients characterized by our group and compare their clinical findings with previous data.

Conclusions

Our data confirm that the cardiovascular prognosis in ATS is less severe than previously reported and that the first years of life are the most critical for possible life-threatening events. Molecular diagnosis is mandatory to distinguish ATS from other CTDs and to define targeted clinical follow-up and timely cardiovascular surgical or interventional treatment, when needed.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-014-0122-5) contains supplementary material, which is available to authorized users.

Artery tortuosity syndrome exhibiting early-onset emphysema with novel compound heterozygous SLC2A10 mutations

We report on a 2-year-old Japanese boy with early-onset pulmonary emphysema, exhibiting dysmorphic face, loose skin, and inguinal and Morgagni hernias. He was admitted to our hospital owing to refractory respiratory infection. On the basis of his clinical features, we investigated the SLC2A10 gene and identified novel compound heterozygous mutations of c.417T > A and c.692G > A, leading to the diagnosis of artery tortuosity syndrome (ATS). This syndrome is an extremely rare autosomal recessive disorder characterized by tortuosity and elongation of the large and medium-sized arteries, hyperextensible skin, and diverse hernias, mostly reported from Europe and Middle Eastern countries, but not from Asia. Although chronic obstructive pulmonary disease, namely, emphysema, has not been well documented in ATS, it may be likely because TGF-beta up-regulation is known to be evoked by SLC2A10 mutations, resulting in reconstruction of pulmonary endothelial cells and emphysema. This is the first report of ATS associated with early-onset pulmonary emphysema, suggesting that patients with ATS may also require close attention for chronic obstructive pulmonary disease.

Aortic Dissection in the Young: A Case Report and Review of the Differential Diagnostic Considerations

Aortic dissection is a rare cause of death in young adults, which may be caused by acquired or congenital factors. We present the case of a 21-year-old man who died as a result of spontaneous aortic dissection and cardiac tamponade. At autopsy, signs of Marfan syndrome were evident both grossly and microscopically. Hodgkin lymphoma was also discovered, though was noncontributory to death. We review the causes of aortic dissection in young individuals, with a focus on the key differentiating features of predisposing inheritable connective tissue disorders. Given the implications for surviving family members, it is the obligation of the diligent forensic pathologist to be aware of these conditions, such that families may be alerted to the need for genetic counseling.

FindZebra: a search engine for rare diseases

BACKGROUND

The web has become a primary information resource about illnesses and treatments for both medical and non-medical users. Standard web search is by far the most common interface to this information. It is therefore of interest to find out how well web search engines work for diagnostic queries and what factors contribute to successes and failures. Among diseases, rare (or orphan) diseases represent an especially challenging and thus interesting class to diagnose as each is rare, diverse in symptoms and usually has scattered resources associated with it.

METHODS

We design an evaluation approach for web search engines for rare disease diagnosis which includes 56 real life diagnostic cases, performance measures, information resources and guidelines for customising Google Search to this task. In addition, we introduce FindZebra, a specialized (vertical) rare disease search engine. FindZebra is powered by open source search technology and uses curated freely available online medical information.

RESULTS

FindZebra outperforms Google Search in both default set-up and customised to the resources used by FindZebra. We extend FindZebra with specialized functionalities exploiting medical ontological information and UMLS medical concepts to demonstrate different ways of displaying the retrieved results to medical experts.

CONCLUSIONS

Our results indicate that a specialized search engine can improve the diagnostic quality without compromising the ease of use of the currently widely popular standard web search. The proposed evaluation approach can be valuable for future development and benchmarking. The FindZebra search engine is available at http://www.findzebra.com/.

Adult presentation of arterial tortuosity syndrome in a 51-year-old woman with a novel homozygous c.1411+1G>A mutation in the SLC2A10 gene

Arterial tortuosity syndrome (ATS) is an autosomal recessive connective tissue disorder, mainly characterized by tortuosity and elongation of the large- and medium-sized arteries with predisposition to stenoses and aneurysms. ATS is caused by mutations in the SLC2A10 gene, encoding for the facilitative glucose transporter 10 (GLUT10) and is described typically in pediatric patients. We report on a 51-year-old woman, originally ascertained because of unexplained widespread chronic pain and positive family history of aortic malformation. The main findings included aged appearance, congenital joint hypermobility, joint instability complications, chronic fatigue syndrome, progressive painful joint stiffness, abdominal hernias, pelvic prolapses, multiple cardiac valve prolapses, varicose veins, easy bruising, and gingival recession. Vascular imaging revealed kinking and anomalous origin of the aortic arch branches, marked tortuosity of the aorta, pulmonary and most middle arteries, and a small aneurysm of the splenic artery. SLC2A10 analysis disclosed homozygosity for the novel c.1411+1G>A splice mutation, leading to a 41 amino acids GLUT10 internal deletion. Expression study by immunofluorescence using healthy control cells showed lack of membrane internalization of GLUT10 in patient's skin fibroblasts. This report describes the first splice-site SLC2A10 mutation and increases to 19 the repertoire of known mutations in this gene. Comparison with the few previously published adult patients with ATS contributes to the natural history of this condition, which is probably under diagnosed within the expanding family of inherited connective tissue disorders.

Medical record and imaging evaluation to identify arterial tortuosity phenotype in populations at risk for intracranial aneurysms

High arterial tortuosity may signify early arterial pathology which may precede development of intracranial aneurysms. We measured arterial tortuosity of intracranial vessels and reviewed the medical records of three groups of patients: with intracranial aneurysms, without aneurysms but at increased clinical risk, and controls without aneurysms or associated risk factors. There was significant but inconsistent evidence of increased arterial tortuosity in aneurysm cases and high-risk cases across different arteries. Medical records review identified that a subset of aneurysm cases carried a diagnosis of Loeys-Dietz syndrome that is often misdiagnosed as Marfan syndrome. We found increased arterial tortuosity in the Loeys-Dietz syndrome cases. A combination of medical record screening for Marfan syndrome or Loeys-Dietz symptoms such as aneurysms and evaluation of arterial tortuosity by a curve of scores from medical images may identify previously undiagnosed cases of Loeys-Dietz syndrome.

Repair of ascending aortic aneurysm in a patient with arterial tortuosity syndrome

Arterial tortuosity syndrome (ATS) is a rare connective tissue disease characterized by aneurysms and stenosis of large elastic arteries. In this case report, we present the case of an eight-year-old with ATS who underwent successful hemi-arch and ascending aortic replacement with tube graft.