Hereditary hemorrhagic telangiectasia: an overview of diagnosis, management, and pathogenesis. Genet Med. 2011;13:607-616. [PMID: 21546842 DOI: 10.1097/gim.0b013e3182136d32]

Imaging to intervention: a review of what the Interventionalist needs to Know about Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a disorder that affects 1 in 5000-10,000 people worldwide and can result in devastating complications such as cerebral abscess, stroke, massive hemorrhage, and even death. HHT is an autosomal dominant disorder that leads to the formation of abnormal communication between the arteries and veins with a resultant spectrum of vascular anomalies. The disorder affects many organ systems and thus requires a dedicated multidisciplinary approach. Interventional radiologists are vital members of this team providing expertise not only in disease management, but in complex embolotherapy, helping to maintain the health of these patients. This article reviews clinical manifestations, screening guidelines, diagnostic criteria, and endovascular management of HHT.

Expanding the Evidence of a Semi-Dominant Inheritance in GDF2 Associated with Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) sometimes co-exists with hereditary hemorrhagic telangiectasia (HHT). Despite being clinically diagnosable according to Curaçao criteria, HHT can be difficult to diagnose due to its clinically heterogenicity and highly overlapping with PAH. Genetic analysis of the associated genes ACVRL1, ENG, SMAD4 and GDF2 can help to confirm or discard the presumptive diagnosis. As part of the clinical routine and to establish a genetic diagnosis, we have analyzed a cohort of patients with PAH and overlapping HHT features through a customized Next Generation Sequencing (NGS) panel of 21 genes, designed and validated in-house. We detected a homozygous missense variant in GDF2 in a pediatric patient diagnosed with PAH associated with HHT and a missense variant along with a heterozygous deletion in another idiopathic PAH patient (compound heterozygous inheritance). In order to establish variant segregation, we analyzed all available family members. In both cases, parents were carriers for the variants, but neither was affected. Our results expand the clinical spectrum and the inheritance pattern associated with GDF2 pathogenic variants suggesting incomplete penetrance and/or variability of expressivity with a semi-dominant pattern of inheritance.

Epidemiological, clinical and endoscopic features of epistaxis severity and quality of life in Hereditary haemorrhagic telangiectasia: a cross-sectional study

BACKGROUND

Epistaxis is the main complaint in patients with Hereditary haemorrhagic telangiectasia (HHT). Even though the role of epistaxis in affecting the quality of life (QoL) is well-known, little is known about epidemiological and clinical factors contributing to epistaxis severity and QoL.

METHODOLOGY

This is a cross-sectional study, including adult patients with HHT with epistaxis. All patients underwent an otolaryngological evaluation with nasal endoscopy. Epistaxis severity was graded using the FID score, and QoL was evaluated with the Short-Form Health Survey (SF-36). Descriptive statistics were produced for demographic characteristics; the Shapiro-Wilk test was used to test the normal distribution of quantitative variables. Correlation between the quantitative variables was evaluated with Pearson's correlation coefficient. Both univariate and multivariate linear regression models were fitted to find associations between demographic or clinical factors and the FID score or SF-36.

RESULTS

A total of 234 patients with HHT were included in the study. The univariate analysis highlighted the association between high blood pressure, septal perforation, nocturnal epistaxis, surgery, blood transfusion, hormonal therapy and both FID score and QoL. Sex, allergic rhinitis and nasal polyposis were neither related to epistaxis severity nor perceived health.

CONCLUSIONS

Epistaxis severity and QoL in patients with HHT are influenced by several clinical factors both dependent and independent from HHT. Some of the results are consistent with those already published, but for the first time, we extended the analysis to different clinical parameters, such as endoscopic findings, never assessed before.

Nasal Endoscopy in the Clinical Diagnosis of Hereditary Hemorrhagic Telangiectasia

OBJECTIVES

To evaluate the role of nasal endoscopy for early clinical diagnosis of hereditary hemorrhagic telangiectasia (HHT) in children and to investigate the characteristics of epistaxis and mucocutaneous telangiectases in our pediatric population.

STUDY DESIGN

From May 2016 to December 2019, a cross-sectional observational study was conducted, recruiting children aged 2-18 years with a parent affected by HHT. To identify the Curaçao criteria, all children underwent collection of clinical history, mucocutaneous examination, and nasal endoscopy. The clinical data were then compared with the genetic data acquired subsequently.

RESULTS

Seventy children (median age, 10.8 years) were included. All underwent nasal endoscopy without complications. Forty-six children were positive by genetic testing; of these, 26 % had skin and oral telangiectases and 91 % had nasal telangiectases. The diagnostic sensitivity of the Curaçao criteria increased from 28 % (95 % CI, 16%-43 %) to 85 % (95 % CI, 71%-94 %; P < .0001) when the nasal telangiectases were included.

CONCLUSIONS

The magnified and complete endoscopic view of the nasal cavities proved useful in increasing the diagnostic sensitivity of the Curaçao criteria. Such an examination turned out to be feasible and safe. For this reason, we believe that nasal endoscopy should be included in the diagnostic assessment of pediatric patients with suspected HHT.

Improvement in epistaxis management: the experience of a dedicated hereditary haemorrhagic telangiectasia clinic

BACKGROUND

Hereditary haemorrhagic telangiectasia (HHT) is a rare genetic vascular disorder which is characterised by the development of arteriovenous malformations and telangiectasias. A key clinical manifestation is recurrent epistaxis. This study examined the impact of a dedicated HHT clinic in a major Australian tertiary hospital on epistaxis symptoms and subjective quality of life.

METHODS

A multidisciplinary HHT clinic was established in 2015. All patients satisfied either genetic diagnosis or fulfilled Curacao criteria. A protocol based clinical assessment was performed and a standardised treatment regimen was implemented. Patients completed quality of life and epistaxis severity score (ESS) questionnaires at each review.

RESULTS

Participants of the dedicated clinic included 21 females (58.3%) and 15 males (41.7%), with a mean age of 49.0 ± 24.0 years. The ACVRL1 variant was the most common (n = 20, 55.6%). A statistically significant reduction in epistaxis severity was noted between the baseline and second review (P = 0.02) and was maintained to the third visit (P = 0.015). Patients older than 50 years demonstrate a consistently higher ESS than those less than 50 years old (P = 0.03). This trend is noted throughout the follow up period with the dedicated clinic.

CONCLUSION

The introduction of a multidisciplinary, dedicated HHT clinic to provide enhanced assessment, monitored treatment regimen and greater access to care, resulted in improvement in the management of epistaxis and quality of life in these patients.

Defective Flow-Migration Coupling Causes Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Activin receptor-like kinase 1 (ALK1) is an endothelial transmembrane serine threonine kinase receptor for BMP family ligands that plays a critical role in cardiovascular development and pathology. Loss-of-function mutations in the ALK1 gene cause type 2 hereditary hemorrhagic telangiectasia, a devastating disorder that leads to arteriovenous malformations. Here, we show that ALK1 controls endothelial cell polarization against the direction of blood flow and flow-induced endothelial migration from veins through capillaries into arterioles.

METHODS

Using Cre lines that recombine in different subsets of arterial, capillary-venous, or endothelial tip cells, we show that capillary-venous Alk1 deletion was sufficient to induce arteriovenous malformation formation in the postnatal retina.

RESULTS

ALK1 deletion impaired capillary-venous endothelial cell polarization against the direction of blood flow in vivo and in vitro. Mechanistically, ALK1-deficient cells exhibited increased integrin signaling interaction with vascular endothelial growth factor receptor 2, which enhanced downstream YAP/TAZ nuclear translocation. Pharmacologic inhibition of integrin or YAP/TAZ signaling rescued flow migration coupling and prevented vascular malformations in Alk1-deficient mice.

CONCLUSIONS

Our study reveals ALK1 as an essential driver of flow-induced endothelial cell migration and identifies loss of flow-migration coupling as a driver of arteriovenous malformation formation in hereditary hemorrhagic telangiectasia disease. Integrin-YAP/TAZ signaling blockers are new potential targets to prevent vascular malformations in patients with hereditary hemorrhagic telangiectasia.

Satisfactory treatment of mucocutaneous lesions in hereditary hemorrhagic telangiectasia patients with dual pulsed dye laser and neodymium: yttrium-aluminum-garnet

Hereditary hemorrhagic telangiectasia (HHT) is characterized by telangiectasia and larger arteriovenous malformations (AVM) in different organs. Mucocutaneous telangiectasia can bleed and cause stigmatization, but the best treatment approach has not been defined yet. The aim of the study was to evaluate the efficacy and safety of dual pulsed dye laser and neodymium: yttrium-aluminum-garnet (PDL-Nd:YAG) laser treatment for mucocutaneous telangiectasia in HHT patients. It is a retrospective case series, where clinical files of all HHT patients treated with PDL-Nd:YAG laser at our Department between December 2010 and July 2019 were reviewed. Demographic, clinical, and treatment characteristics were recorded. The severity and degree of improvement were evaluated by three blinded examiners scoring pretreatment and posttreatment pictures on a 5-point scale. Patient satisfaction and procedure pain were assessed using an ordinal scale (0-10). Forty-three treatment areas from 26 patients were analyzed. Lesions were predominantly located on the lower lip and cheeks. The median number of laser sessions per patient was 3 (interquartile range [IQR] 2-4). The median global severity score at baseline was 2 and became 0 at endpoint (p < 0.0001), with a median improvement rate of 4 (IQR 3-4). All patients reported a high degree of satisfaction (median 9) and tolerable pain (median 5). In conclusion, dual PDL-Nd: YAG laser is a convenient, safe, and effective treatment option for mucocutaneous telangiectasia in HHT patients.

Pediatric Spinal Cord Diseases

Spinal cord diseases in pediatric patients are highly variable in terms of presentation, pathology, and prognosis. Not only do they differ with respect to each other but so too with their adult equivalents. Some of the most common diseases are autoimmune (ie, multiple sclerosis, acute disseminated encephalomyelitis, and acute transverse myelitis), congenital (ie, dysraphism with spina bifida, split cord malformation, and tethered cord syndrome), tumor (ie, juvenile pilocytic astrocytoma, ependymoma, and hem-angioblastoma), and vascular (ie, cavernous malformations, arteriovenous malformations, and dural arteriovenous fistulas) in nature. These each require their own niche treatment paradigm and prognosis. Furthermore, presentation of different spinal cord diseases in children can be difficult to discern without epidemiologic and imaging data. Interpretation of these data is crucial to facilitating a timely and accurate diagnosis. Correspondingly, the aim of this review was to highlight the most pertinent features of the most common spinal cord diseases in the pediatric population.

Genetic counseling and testing for hereditary hemorrhagic telangiectasia

Genetic counseling is an important means of identifying a patient's genetic risk of hereditary hemorrhagic telangiectasia (HHT) and assisting patients in making informed decisions about their health. With an increase in understanding of the genetic mechanisms underlying HHT over the last decade, genetic counseling is increasingly being incorporated into the care of patients affected by HHT. In addition to refining the diagnosis of symptomatic patients, genetic testing can help to distinguish asymptomatic, at-risk patients from those who are unaffected by HHT. The purpose of this review article is to summarize the current knowledge regarding the role of genetic counseling and genetic testing in identifying and managing HHT in at-risk populations. This article also reviews the guidelines, outcomes, risks, and challenges of genetic counseling and testing for HHT in various patient populations, and provides an algorithm for the use of genetic counseling in symptomatic and asymptomatic patients.

Progress and prospects of mechanotransducers in shear stress-sensitive signaling pathways in association with arteriovenous malformation

Arteriovenous malformations are congenital vascular lesions characterized by a direct and tangled connection between arteries and veins, which disrupts oxygen circulation and normal blood flow. Arteriovenous malformations often occur in the patient with hereditary hemorrhagic telangiectasia. The attempts to elucidate the causative factors and pathogenic mechanisms of arteriovenous malformations are now still in progress. Some studies reported that shear stress in blood flow is one of the factors involved in arteriovenous malformations manifestation. Through several mechanotransducers harboring the endothelial cells membrane, the signal from shear stress is transduced towards the responsible signaling pathways in endothelial cells to maintain cell homeostasis. Any disruption in this well-established communication will give rise to abnormal endothelial cells differentiation and specification, which will later promote arteriovenous malformations. In this review, we discuss the update of several mechanotransducers that have essential roles in shear stress-induced signaling pathways, such as activin receptor-like kinase 1, Endoglin, Notch, vascular endothelial growth factor receptor 2, Caveolin-1, Connexin37, and Connexin40. Any disruption of these signaling potentially causes arteriovenous malformations. We also present some recent insights into the fundamental analysis, which attempts to determine potential and alternative solutions to battle arteriovenous malformations, especially in a less invasive and risky way, such as gene treatments.

A novel endoglin mutation in a family with hereditary hemorrhagic telangiectasia: a case report

Hereditary hemorrhagic telangiectasis (HHT) is an autosomal dominant vascular disease, and approximately 80% of all HHT cases are caused by gene mutation. In this report, we analyzed the case of an 11-year-old girl who had intracranial bleeding when she was 7 years old. Her brain computed tomography (CT) scans and craniocerebral angiography results revealed that she had multiple cerebral arteriovenous malformations (CAVMs). Cardiac computed tomography angiography (CTA) revealed a pulmonary arteriovenous malformation (PAVM) located in a segment of the left lung. This patient's primary diagnosis was of CAVMs and PAVMs. Both cerebral vascular embolization therapy and interventional treatment for PAVMs were performed to treat these respective conditions. The operations were successful and the patient's prognosis was good. To confirm the patient's diagnosis and the cause of her conditions, peripheral blood was collected from her and her family for whole-exome sequencing (WES). Sanger sequencing was used to verify these results and STRUM software was used to predict the presence of mutant proteins. We found a new mutation of the endoglin (ENG) gene present in this family; this mutation is known as c.1466del (p.Gln489Argfs*2). The patient's mother was a carrier of this heterozygous mutation. STRUM software confirmed that the configuration of the ENG protein p.Gln489Argfs2 site changed with this mutation. We believe this c.1466del (p.Gln489Argfs*2) mutation affects ENG protein function, and the resultant ENG protein dysfunction leads to HHT. When a child has multiple vascular malformation, HHT should be considered as a primary diagnosis.

A Tale of Two Organ Systems: Imaging Review of Diseases Affecting the Thoracic and Neurological Systems. Part 2

In an era of rapidly expanding knowledge and sub-specialization, it is becoming increasingly common to focus on one organ system. However, the human body is intimately linked, and disease processes affecting one region of the body not uncommonly affect the other organ systems as well. Understanding diseases from a macroscopic perspective, rather than a narrow vantage point, enables efficient and accurate diagnosis. This tenet holds true for diseases affecting both the thoracic and neurologic systems; in isolation, the radiologic appearance of disease in one organ system may be nonspecific, but viewing the pathophysiologic process in both organ systems may markedly narrow the differential considerations, and potentially lead to a definitive diagnosis. In this article, we discuss a variety of disease entities known to affect both the thoracic and neurological systems, either manifesting simultaneously or at different periods of time. Some of these conditions may show neither thoracic nor neurological manifestations. These diseases have been systematically classified into infectious, immune-mediated/ inflammatory, vascular, syndromic/ hereditary and neoplastic disorders. The underlying pathophysiological mechanisms linking both regions and radiologic appearances in both organ systems are discussed. When appropriate, brief clinical and diagnostic information is provided. Ultimately, accurate diagnosis will lead to expedited triage and prompt institution of potentially life-saving treatment for these groups of complex disorders.

Lung Pericytes in Pulmonary Vascular Physiology and Pathophysiology

Pericytes are mesenchymal-derived mural cells localized within the basement membrane of pulmonary and systemic capillaries. Besides structural support, pericytes control vascular tone, produce extracellular matrix components, and cytokines responsible for promoting vascular homeostasis and angiogenesis. However, pericytes can also contribute to vascular pathology through the production of pro-inflammatory and pro-fibrotic cytokines, differentiation into myofibroblast-like cells, destruction of the extracellular matrix, and dissociation from the vessel wall. In the lung, pericytes are responsible for maintaining the integrity of the alveolar-capillary membrane and coordinating vascular repair in response to injury. Loss of pericyte communication with alveolar capillaries and a switch to a pro-inflammatory/pro-fibrotic phenotype are common features of lung disorders associated with vascular remodeling, inflammation, and fibrosis. In this article, we will address how to differentiate pericytes from other cells, discuss the molecular mechanisms that regulate the interactions of pericytes and endothelial cells in the pulmonary circulation, and the experimental tools currently used to study pericyte biology both in vivo and in vitro. We will also discuss evidence that links pericytes to the pathogenesis of clinically relevant lung disorders such as pulmonary hypertension, idiopathic lung fibrosis, sepsis, and SARS-COVID. Future studies dissecting the complex interactions of pericytes with other pulmonary cell populations will likely reveal critical insights into the origin of pulmonary diseases and offer opportunities to develop novel therapeutics to treat patients afflicted with these devastating disorders. © 2021 American Physiological Society. Compr Physiol 11:2227-2247, 2021.

Development and Validation of the Nasal Outcome Score for Epistaxis in Hereditary Hemorrhagic Telangiectasia (NOSE HHT)

Importance

Epistaxis is the greatest cause of morbidity in patients with hereditary hemorrhagic telangiectasia (HHT); because of this, a validated epistaxis-specific quality-of-life instrument for HHT should be made available.

Objective

To develop and validate an epistaxis-specific quality-of-life patient-reported outcome measure for HHT.

Design, Setting, and Participants

This survey study focused on the development and validation of the Nasal Outcome Score for Epistaxis (NOSE) in HTT (NOSE HHT) outcome measure with data prospectively collected from December 10, 2019, to March 15, 2020. A total of 401 patients were recruited from within the Cure Hemorrhagic Telangiectasia online patient advocacy social media network, the Washington University HHT Center of Excellence, and a randomized clinical trial investigating an intranasal timolol gel for HHT-associated epistaxis.

Main Outcomes and Measures

Face and content validity, factor analysis, internal consistency as measured through Cronbach α, construct validity, responsiveness to change, and minimal clinically important difference.

Results

The NOSE HHT was developed and validated with a possible score ranging discretely from 0 to 4 for each of the 29 items and a total score ranging continuously from 0 to 4 after dividing by the total number of items answered. A total of 401 participants completed the NOSE HHT. Factor analysis identified 3 factors that matched the a priori specified subgroups of particular aspects of life affected by HHT-associated epistaxis: physical problems (mean [SD] magnitude, 1.59 [0.83]), functional limitations (mean [SD] magnitude, 1.28 [0.84]), and emotional consequences (mean [SD] magnitude, 1.95 [1.02]). The instrument had high internal consistency with an overall Cronbach α of 0.960. Convergent validity determined the total NOSE HHT score to be a strong predictor of disease severity; total NOSE HHT score can be split up into the following epistaxis severity categories: mild (0-1), moderate (1.01-2), and severe (>2). The instrument was found to be sensitive to change, and the minimal clinically important difference for the total NOSE HHT score was 0.46.

Conclusions and Relevance

Evaluation of the consistency, reliability, and responsiveness of the NOSE HHT survey found it to be a valid instrument to assess severity and change in epistaxis. Study results suggest that the NOSE HHT survey is clinically applicable and useful as an outcome measure of future HHT-associated epistaxis trials.

Beneficial Effects of Remote Medical Care for Patients with Hereditary Hemorrhagic Telangiectasia during the COVID-19 Pandemic

Background: Hereditary hemorrhagic telangiectasia (HHT) needs high-quality care and multidisciplinary management. During the COVID-19 pandemic, most non-urgent clinical activities for HHT outpatients were suspended. We conducted an analytical observational cohort study to evaluate whether medical and psychological support, provided through remote consultation during the COVID-19 pandemic, could reduce the complications of HHT. Methods: A structured regimen of remote consultations, conducted by either video-calls, telephone calls, or e-mails, was provided by a multidisciplinary group of physicians to a set of patients of our HHT center. The outcomes considered were: number of emergency room visits/hospitalizations, need of blood transfusions, need of iron supplementation, worsening of epistaxis, and psychological status. Results: The study included 45 patients who received remote assistance for a total of eight months. During this period, 9 patients required emergency room visits, 6 needed blood transfusions, and 24 needed iron supplementation. This was not different from what was registered among the same 45 patients in the same period of the previous year. Remote care also resulted in better management of epistaxis and improved quality of life, with the mean epistaxis severity score and the Euro-Quality of Life-Visual Analogue Scale that were significantly better at the end than at the beginning of the study. Discussion: Remote medical care might be a valid support for HHT subjects during periods of suspended outpatient surveillance, like the COVID-19 pandemic.

Precision Medicine Approaches to Vascular Disease: JACC Focus Seminar 2/5

In this second of a 5-part Focus Seminar series, we focus on precision medicine in the context of vascular disease. The most common vascular disease worldwide is atherosclerosis, which is the primary cause of coronary artery disease, peripheral vascular disease, and a large proportion of strokes and other disorders. Atherosclerosis is a complex genetic disease that likely involves many hundreds to thousands of single nucleotide polymorphisms, each with a relatively modest effect for causing disease. Conversely, although less prevalent, there are many vascular disorders that typically involve only a single genetic change, but these changes can often have a profound effect that is sufficient to cause disease. These are termed "Mendelian vascular diseases," which include Marfan and Loeys-Dietz syndromes. Given the very different genetic basis of atherosclerosis versus Mendelian vascular diseases, this article was divided into 2 parts to cover the most promising precision medicine approaches for these disease types.

An advanced ultrasound application used to assess peripheral vascular diseases: superb microvascular imaging

Over the past several years, a novel ultrasound imaging modality termed superb microvascular imaging (SMI) has enabled visualization of microvessels. SMI ultrasound studies of peripheral artery diseases have significantly extended our knowledge of tissue microcirculation and the arterial microenvironments of atherosclerotic lesions. We here present an overview of current knowledge on the utility of SMI assessment of vascular diseases and highlight certain peripheral microcirculation disorders for which SMI is particularly valuable. The evidence indicates that SMI can detect intraplaque neovascularization and usefully assess carotid plaque vulnerability; vascularization of the carotid arterial wall detected by SMI is a potential marker of disease activity in patients with Takayasu arteritis; SMI reveals the foot microcirculation and yields a quantitative vascular index (in line with the angiosome concept); and, SMI may serve as an auxiliary diagnostic modality for hereditary hemorrhagic telangiectasia and Raynaud syndrome. In general, microcirculatory evaluation by SMI is an attractive field for future research on therapeutic strategies for peripheral vascular diseases.

Clinical and molecular characterization of patients with hereditary hemorrhagic telangiectasia: Experience from an HHT Center of Excellence

In this retrospective single-center study, we evaluated whether/how pathogenic/likely pathogenic variants of three hereditary hemorrhagic telangiectasia (HHT)-associated genes (ENG, ACVRL1, and SMAD4) are associated with specific clinical presentations of HHT. We also characterized the morphological features of pulmonary arteriovenous malformations (AVMs) in patients with these variants. Pathogenic or likely pathogenic variants were detected in 64 patients. Using nonparametric statistical tests, we compared the type and prevalence of specific HHT diagnostic features associated with these three variants. Pathogenic variants in these genes resulted in gene-specific HHT clinical presentations. Epistaxis was present in 93%, 94%, and 100% of patients with ENG, ACVRL1, and SMAD4 variants, respectively (p = 0.79). Pulmonary AVMs were more common in patients with the ENG variant (p = 0.034) compared with other subgroups. ACVRL1 variant was associated with the lowest frequency of pulmonary AVMs (p = 0.034) but the highest frequency of hepatic AVMs (p = 0.015). Patients with the ACVRL1 variant did not have significantly more pancreatic AVMs compared with the other groups (p = 0.72). ENG, ACVRL1, and SMAD4 pathogenic or likely pathogenic variants are associated with gene-specific HHT presentations, which is consistent with results from other HHT centers.

Resolving Differential Diagnostic Problems in von Willebrand Disease, in Fibrinogen Disorders, in Prekallikrein Deficiency and in Hereditary Hemorrhagic Telangiectasia by Next-Generation Sequencing

Diagnosis of rare bleeding disorders is challenging and there are several differential diagnostics issues. Next-generation sequencing (NGS) is a useful tool to overcome these problems. The aim of this study was to demonstrate the usefulness of molecular genetic investigations by summarizing the diagnostic work on cases with certain bleeding disorders. Here we report only those, in whom NGS was indicated due to uncertainty of diagnosis or if genetic confirmation of initial diagnosis was required. Based on clinical and/or laboratory suspicion of von Willebrand disease (vWD, n = 63), hypo-or dysfibrinogenemia (n = 27), hereditary hemorrhagic telangiectasia (HHT, n = 10) and unexplained activated partial thromboplastin time (APTT) prolongation (n = 1), NGS using Illumina platform was performed. Gene panel covered 14 genes (ACVRL1, ENG, MADH4, GDF2, RASA1, F5, F8, FGA, FGB, FGG, KLKB1, ADAMTS13, GP1BA and VWF) selected on the basis of laboratory results. We identified forty-seven mutations, n = 29 (6 novel) in vWD, n = 4 mutations leading to hemophilia A, n = 10 (2 novel) in fibrinogen disorders, n = 2 novel mutations in HHT phenotype and two mutations (1 novel) leading to prekallikrein deficiency. By reporting well-characterized cases using standardized, advanced laboratory methods we add new pieces of data to the continuously developing “bleeding disorders databases”, which are excellent supports for clinical patient management.

Safety of Catheter Embolization of Pulmonary Arteriovenous Malformations-Evaluation of Possible Cerebrovascular Embolism after Catheter Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia/Osler Disease by Pre- and Post-Interventional DWI

BACKGROUND

This paper aimed to prospectively evaluate the safety of embolization therapy of pulmonary arteriovenous malformations (PAVMs) for the detection of cerebral infarctions by pre- and post-interventional MRI. Method One hundred and five patients (male/female = 44/61; mean age 48.6+/-15.8; range 5-86) with pre-diagnosed PAVMs on contrast-enhanced MRA underwent embolization therapy. The number of PAVMs treated in each patient ranged from 1-8 PAVMs. Depending on the size and localization of the feeding arteries, either Nester-Coils or Amplatzer vascular plugs were used for embolization therapy. cMRI was performed immediately before, and at the 4 h and 3-month post-embolization therapy. Detection of peri-interventional cerebral emboli was performed via T2w and DWI sequences using three different b-values, with calculation of ADC maps. Results Embolization did not show any post-/peri-interventional, newly developed ischemic lesions in the brain. Only one patient who underwent re-embolization and was previously treated with tungsten coils that corroded over time showed newly developed, small, diffuse emboli in the post-interventional DWI sequence. This patient already had several episodes of brain emboli before re-treatment due to the corroded coils, and during treatment, when passing the corroded coils, experienced additional small, clinically inconspicuous brain emboli. However, this complication was anticipated but accepted, since the vessel had to be occluded distally. Conclusion Catheter-based embolization of PAVMs is a safe method for treatment and does not result in clinically inconspicuous cerebral ischemia, which was not demonstrated previously.

Somatic Mosaicism in the Pathogenesis of de novo Cerebral Arteriovenous Malformations: A Paradigm Shift Implicating the RAS-MAPK Signaling Cascade

Cerebral arteriovenous malformations (AVMs) are leading causes of lesional hemorrhagic stroke in both the pediatric and young adult population, with sporadic AVMs accounting for the majority of cases. Recent evidence has identified somatic mosaicism in key proximal components of the RAS-MAPK signaling cascade within endothelial cells collected from human sporadic cerebral AVMs, with early preclinical models supporting a potential causal role for these mutations in the pathogenesis of these malformations. Germline mutations that predispose to deregulation of the RAS-MAPK signaling axis have also been identified in hereditary vascular malformation syndromes, highlighting the key role of this signaling axis in global AVM development. Herein, we review the most recent genomic and preclinical evidence implicating somatic mosaicism in the RAS-MAPK signaling pathway in the pathogenesis of sporadic cerebral AVMs. Also, we review evidence for RAS-MAPK dysregulation in hereditary vascular malformation syndromes and present a hypothesis suggesting that this pathway is central for the development of both sporadic and syndrome-associated AVMs. Finally, we examine the clinical implications of these recent discoveries and highlight potential therapeutic targets within this signaling pathway.

KRAS/BRAF mutations in brain arteriovenous malformations: A systematic review and meta-analysis

INTRODUCTION

Somatic KRAS mutations have been identified in the majority of brain arteriovenous malformations (AVM) specimens. The aim of our study was to evaluate the prevalence of Kirsten rat sarcoma (KRAS)/murine sarcoma viral oncogene homolog B1 (BRAF) mutations in brain AVM.

METHODS

A systematic literature review was performed in November 2019. We reviewed MEDLINE/PubMed, Cochrane Library, and ClinicalTrials.gov for citation or ongoing trials from January 2010 to March 2020.

RESULTS

6 studies were identified as meeting the inclusion criteria of this review. The total frequency of KRAS mutations in 1726 patients with AVM was 55%. The prevalence of BRAF mutation was 7.5%. The prevalence of AVMs with grade 2 was the most (39%). Frontal and parietal lobes were the commonest sites of AVMs (21%). the most prevalent presentation of patients with AVM was hemorrhage (62%).

CONCLUSION

Our findings support a high prevalence of somatic activating mutations in KRAS and less commonly, BRAF in the overwhelming majority of brain AVMs. Practically and importantly, this pathway homogeneity in CNS arteriovenous malformations also supports the development of targeted therapies with RAS/RAF pathway inhibitors. However, more studies are needed to confirm this hypothesis.

Non-Coding RNAs and Hereditary Hemorrhagic Telangiectasia

Non-coding RNAs (ncRNAs) are functional ribonucleic acid (RNA) species that include microRNAs (miRs), a class of short non-coding RNAs (∼21–25 nucleotides), and long non-coding RNAs (lncRNAs) consisting of more than 200 nucleotides. They regulate gene expression post-transcriptionally and are involved in a wide range of pathophysiological processes. Hereditary hemorrhagic telangiectasia (HHT) is a rare disorder inherited in an autosomal dominant fashion characterized by vascular dysplasia. Patients can develop life-threatening vascular malformations and experience severe hemorrhaging. Effective pharmacological therapies are limited. The study of ncRNAs in HHT is an emerging field with great promise. This review will explore the current literature on the involvement of ncRNAs in HHT as diagnostic and pathogenic factors.

Topical Propranolol Improves Epistaxis Control in Hereditary Hemorrhagic Telangiectasia (HHT): A Randomized Double-Blind Placebo-Controlled Trial

Epistaxis is a common debilitating manifestation in hereditary hemorrhagic telangiectasia (HHT), due to mucocutaneous telangiectases. The epistaxis can be difficult to control despite available treatments. Dysregulated angiogenesis has been shown to be associated with telangiectases formation. Topical propranolol has demonstrated antiangiogenic properties. We performed a two-phase study, i.e., a double-blind placebo-controlled phase, followed by an open-label phase. The aim of the study was assessment of safety and efficacy of nasal propranolol gel in HHT-related epistaxis. Twenty participants with moderate-severe HHT-related epistaxis were randomized to eight weeks of propranolol gel 1.5%, or placebo 0.5 cc, applied to each nostril twice daily; and continued propranolol for eight weeks in an open-label study. For the propranolol group, the epistaxis severity score (ESS) improved significantly (-2.03 ± 1.7 as compared with -0.35 ± 0.68 for the placebo group, p = 0.009); hemoglobin levels improved significantly (10.5 ± 2.6 to 11.4 ± 2.02 g/dL, p = 0.009); and intravenous iron and blood transfusion requirement decreased. The change in nasal endoscopy findings was not significant. During the open-label period, the ESS score improved significantly in the former placebo group (-1.99 ± 1.41, p = 0.005). The most common adverse event was nasal mucosa burning sensation. No cardiovascular events were reported. Our results suggest that topical propranolol gel is safe and effective in HHT-related epistaxis.

Differential Expression of Circulating Plasma miRNA-370 and miRNA-10a from Patients with Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant, vascular disorder that presents with telangiectases and arteriovenous malformations. HHT is a genetically heterogeneous disorder, involving mutations in endoglin (ENG; HHT1) and activin receptor-like kinase 1 (ACVRL1/ALK1; HHT2) genes that account for over 85% of all HHT patients. The current diagnosis of HHT patients remains at the clinical level, but many suspected patients do not have a clear HHT diagnosis or do not show pathogenic mutations in HHT genes. This situation has prompted the search for biomarkers to help in the early diagnosis of the disease. We have analyzed the plasma levels in HHT patients of selected micro-RNAs (miRNAs), small single-stranded RNAs that regulate gene expression at the transcriptional level by interacting with specific RNA targets. A total of 16 HHT1 and 17 HHT2 plasma samples from clinically confirmed patients and 16 controls were analyzed in this study. Total RNA was purified from plasma, and three selected miRNAs (miRNA-10a, miRNA-214, and miRNA-370), related to the pathobiology of cardiovascular diseases and potentially targeting ENG or ALK1, were measured by quantitative polymerase chain reaction. Compared with controls, levels of miRNA-370, whose putative target is ENG, were significantly downregulated in HHT1, but not in HHT2, whereas the levels of miRNA-10a, whose putative target is ALK1, were significantly upregulated in HHT2, but not in HHT1. In addition, the levels of miRNA-214, potentially targeting ENG and ALK1, did not change in either HHT1 or HHT2 patients versus control samples. While further studies are warranted, these results suggest that dysregulated plasma levels of miRNA-370 or miRNA-10a could help to identify undiagnosed HHT1 or HHT2 patients, respectively.

Cell-free DNA next-generation sequencing liquid biopsy as a new revolutionary approach for arteriovenous malformation

Objective

Somatic mosaicism of KRAS gene is currently recognized as the only established molecular basis of arteriovenous malformations (AVM). However, given the limitations of the current technologies, KRAS somatic mutations are detected only in a limited proportion of AVMs and tissue biopsy remains an invasive high risky, sometimes life-threatening, diagnostic procedure. Next-generation sequencing liquid biopsy using cell-free DNA (cfDNA) has emerged as an innovative noninvasive approach for early detection and monitoring of cancer. This approach overcomes the space-time profile constraint of tissue biopsies opens a new scenario for vascular malformations owing to somatic mosaicism. Here, we propose a new approach as a fast noninvasive reliable tool in order to investigate the cfDNA coming from the AVMs.

Methods

A group of five patients suffering from AVM were selected. Blood samples from peripheral vein and efferent vein from vascular malformation were collected and cfDNA was extracted. The cfDNA libraries were performed using Oncomine Pan-Cancer Cell-Free Assay. We used Ion Proton for sequencing and Ion Reporter Software for analysis (Life Technologies, Carlsbad, Calif).

Results

In all cases, either G12D or G12V mutations in KRAS were identified. The mutational load was higher in the efferent vein than in peripheral blood, confirming the causative role of the identified mutation at a somatic level.

Conclusions

We demonstrate that cfDNA next-generation sequencing liquid biopsy is able to identify the KRAS mutation detected in affected tissues. Moreover, we have shown that blood sample withdrawal at the lesion site increases variant allele frequency with an order of magnitude above the limit of detection (usually 0.05%), decreasing the risk of a false negative. Finally, the noninvasiveness of the method avoids any risk of bleeding, being easily performed also in children. We propose this technique as the method of choice to better investigate AVMs and consequently to identify the therapy tailored to the genetic defect.

Clinical Relevance

This article highlights the importance of using liquid biopsy as a new method to investigate the molecular profile of AVMs. In view of the frequent inaccessibility of vascular tissues owing to the invasiveness of solid biopsy and the relative high incidence of biopsies with low diagnostic power, here we evaluated the efficacy of detecting cfDNA fragments released into the bloodstream from the affected tissue cells. Through a simple blood draw from the efferent vein at the vascular malformation site, the liquid biopsy allowed us to identify KRAS pathogenic mutations piloting a personalized therapeutic approach and opening a new scenario for new therapeutic strategies.

Cerebrovascular Malformations in a Pediatric Hereditary Hemorrhagic Telangiectasia Cohort

BACKGROUND

We determined the frequency of cerebrovascular malformations in a pediatric cohort with hereditary hemorrhagic telangiectasia.

METHODS

Retrospective cohort study of 54 children diagnosed with hereditary hemorrhagic telangiectasia at a tertiary care center. All neuroimaging was reviewed to assess for number and types of cerebrovascular malformations and for intracerebral hemorrhage and arterial ischemic stroke. Clinical charts were reviewed for clinical manifestations, genetic mutation, and clinically evident intracerebral hemorrhages and arterial ischemic strokes.

RESULTS

Among 54 children with hereditary hemorrhagic telangiectasia with a median age of 3.5 years (interquartile range 0.4 to 7.9 years) at diagnosis, neuroimaging was performed in 52 (96.3%) at a median age of 5.2 years (interquartile range 1.8 to 9 years). Fourteen of 52 imaged children (26.9%) had cerebrovascular malformations. Cerebrovascular malformations included arteriovenous malformations, arteriovenous fistulas, vein of Galen malformations, and developmental venous anomalies. Six of the 14 children with cerebrovascular malformations (42.9%) had multiple malformations. Three children developed new cerebral arteriovenous malformations over time. Six children (11.1%) had clinically evident intracerebral hemorrhage, arterial ischemic stroke, or transient ischemic attack. The three children with intracerebral hemorrhage presented at young ages (4.3 to 7.7 years).

CONCLUSIONS

More than a quarter of children with hereditary hemorrhagic telangiectasia who were imaged had cerebrovascular malformations, and overt stroke occurred in more than 10%. Intracerebral hemorrhages can occur in pediatric hereditary hemorrhagic telangiectasia patients at young ages, and new cerebral arteriovenous malformations may develop over time. Early screening with neuroimaging including neurovascular imaging as well as repeat neuroimaging may be warranted in children with hereditary hemorrhagic telangiectasia.

Hereditary hemorrhagic telangiectasia associated with cortical development malformation due to a start loss mutation in ENG

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT), also known as Rendu-Osler-Weber syndrome, is a rare disorder characterized by recurrent epistaxis, telangiectasias and systemic arteriovenous malformations (AVMs). HHT is associated with mutations in genes encoding for proteins involved in endothelial homeostasis such as ENG (endoglin) and ACVRL1 (activin receptor-like kinase-1).

CASE PRESENTATION

Here we describe a 22-year-old male presenting with a transient episode of slurred speech and left arm paresis. Brain MRI displayed polymicrogyria. A right-to-left shunt in absence of an atrial septum defect was noted. Chest CT revealed multiple pulmonary AVMs, likely causing paradoxical embolism manifesting as a transient ischemic attack. The heterozygous ENG variant, c.3G > A (p.Met1lle), was detected in the patient. This variant was also found in patient's mother and in his younger brother who displayed cortical dysplasia type 2.

CONCLUSIONS

The detection of cortical development malformations in multiple subjects from the same pedigree may expand the phenotypic features of ENG-related HHT patients. We suggest considering HHT in young patients presenting with acute cerebral ischemic events of unknown origin.

Integration of clinical parameters, genotype and epistaxis severity score to guide treatment for hereditary hemorrhagic telangiectasia associated bleeding

BACKGROUND

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare inherited disorder characterized by development of mucocutaneous telangiectases and visceral organ arteriovenous malformations, which can lead to recurrent, spontaneous bleeding and development of iron deficiency anemia. The primary objective of this study was to ascertain the relationship between epistaxis severity scores (ESS), laboratory values, genotype, and phenotype in HHT. Our secondary objective was to assess efficacy of systemic antifibrinolytic therapy in reducing ESS in HHT.

METHODOLOGY

We conducted a retrospective review of patients seen at the UNC HHT Center from January 1, 2009 to February 28, 2015. ESS, demographics, and results of genetic testing were abstracted from the medical record. Response to antifibrinolytic therapy was evaluated by comparing pre-post ESS.

RESULTS

One hundred and forty nine patients were eligible with 116 having genetic testing and 33 without. Age, hemoglobin and ferritin levels were predictive of ESS. Of the 116 patients that underwent genetic testing: 63 had an ACVRL1 mutation, 40 had an ENG mutation, 2 had a SMAD4 mutation, and 11 patients had no pathologic HHT genetic variation detected. Compared to patients without a detectable HHT-associated genetic variation, patients with a HHT-associated genetic variation had higher ESS scores (p < 0.05). Neither ESS nor genotype was predictive of pulmonary or brain AVMs. Twenty-four HHT patients with ESS > 4 were started on antifibrinolytic therapy (tranexamic acid or aminocaproic acid) and had a post-treatment ESS recorded. All patients had a decrease in ESS of > 0.71 (minimal meaningful difference), but patients taking antifibrinolytics displayed larger decreases. No patients on antifibrinolytics experienced a VTE with median follow up of 13 months.

CONCLUSIONS

We demonstrate that the ESS correlates with age, hemoglobin and ferritin. Additionally, we demonstrate that HHT patients with genetic mutations have higher ESS scores. Our data demonstrate that antifibrinolytics are effective in decreasing epistaxis severity and safe with long-term use in HHT patients.

Deregulation of Drosha in the pathogenesis of hereditary hemorrhagic telangiectasia

PURPOSE OF REVIEW

The TGFβ (transforming growth factor β) superfamily - a large group of structurally related and evolutionarily conserved proteins - profoundly shapes and organizes the vasculature during normal development and adult homeostasis. Mutations inactivating several of its ligands, receptors, or signal transducers set off hereditary hemorrhagic telangiectasia (HHT), a disorder that causes capillary networks to form incorrectly. Drosha, an essential microRNA-processing enzyme, also interfaces with TGFβ signal transducers, but its involvement in vascular conditions had not been tested until recently. This review summarizes current evidence that links mutations of Drosha to HHT.

RECENT FINDINGS

Genetic studies have revealed that rare missense mutations in the Drosha gene occur more commonly among HHT patients than in healthy people. Molecular analyses also indicated that Drosha enzymes with HHT-associated mutations generate microRNAs less efficiently than their wild-type counterpart when stimulated by TGFβ ligands. In zebrafish or mouse, mutant Drosha proteins cause the formation of dilated, leaky blood vessels deprived of capillaries, similar to those typically found in patients with HHT.

SUMMARY

Recent evidence suggests that Drosha-mediated microRNA biogenesis contributes significantly to the control of vascular development and homeostasis by TGFβ. Loss or reduction of Drosha function may predispose carriers to HHT and possibly other vascular diseases.

The future is here: Integrating genetics into the pediatric pulmonary clinic

Recognition of underlying genetic etiologies of disease is increasing at an exponential rate, likely due to greater access to and lower cost of genetic testing. Monogenic causes of disease, or conditions resulting from a mutation or mutations in a single gene, are now well recognized in every subspecialty, including pediatric pulmonary medicine; thus, it is important to consider genetic conditions when evaluating children with respiratory disease. In the pediatric pulmonary clinic, genetic testing should be considered when multiple family members present with similar or related clinical features and when individuals have unusual clinical presentations, such as early-onset disease or complex, syndromic features. This review provides a practical guide for genetic diagnosis in the pediatric pulmonary setting, including a review of genetic concepts, considerations for test selection and results in interpretation, as well as an overview of genetic differential diagnoses for common pediatric pulmonary phenotypes. Genetic conditions that commonly present to the pediatric pulmonary clinic are reviewed in a companion article by Yonker et al.

Recognizing genetic disease: A key aspect of pediatric pulmonary care

Advancement in technology has improved recognition of genetic etiologies of disease, which has impacted diagnosis and management of rare disease patients in the pediatric pulmonary clinic. This review provides an overview of genetic conditions that are likely to present with pulmonary features and require extensive care by the pediatric pulmonologist. Increased familiarity with these conditions allows for improved care of these patients by reducing time to diagnosis, tailoring management, and prompting further investigation into these disorders.

A pilot study of next generation sequencing-liquid biopsy on cell-free DNA as a novel non-invasive diagnostic tool for Klippel-Trenaunay syndrome

OBJECTIVES

Somatic mosaicism of PIK3CA gene is currently recognized as the molecular driver of Klippel-Trenaunay syndrome. However, given the limitation of the current technologies, PIK3CA somatic mutations are detected only in a limited proportion of Klippel-Trenaunay syndrome cases and tissue biopsy remains an invasive high risky, sometimes life-threatening, diagnostic procedure. Next generation sequencing liquid biopsy using cell-free DNA has emerged as an innovative non-invasive approach for early detection and monitoring of cancer. This approach, overcoming the space-time profile constraint of tissue biopsies, opens a new scenario also for others diseases caused by somatic mutations.

METHODS

In the present study, we performed a comprehensive analysis of seven patients (four females and three males) with Klippel-Trenaunay syndrome. Blood samples from both peripheral and efferent vein from malformation were collected and cell-free DNA was extracted from plasma. Tissue biopsies from vascular lesions were also collected when available. Cell-free DNA libraries were performed using Oncomine™ Pan-Cancer Cell-Free Assay. Ion Proton for sequencing and Ion Reporter Software for analysis were used (Life Technologies, Carlsbad, CA, USA).

RESULTS

Cell-free circulating DNA analysis revealed pathogenic mutations in PIK3CA gene in all patients. The mutational load was higher in plasma obtained from the efferent vein at lesional site (0.81%) than in the peripheral vein (0.64%) leading to conclude for a causative role of the identified variants. Tissue analysis, available for one amputated patient, confirmed the presence of the mutation at the malformation site at a high molecular frequency (14-25%), confirming its causative role.

CONCLUSIONS

Our data prove for the first time that the cell-free DNA-next generation sequencing-liquid biopsy, which is currently used exclusively in an oncologic setting, is indeed the most effective tool for Klippel-Trenaunay syndrome diagnosis and tailored personalized treatment.

Emerging importance of molecular pathogenesis of vascular malformations in clinical practice and classifications

Vascular malformations occur during early vascular development resulting in abnormally formed vessels that can manifest as arterial, venous, capillary or lymphatic lesions, or in combination, and include local tissue overdevelopment. Vascular malformations are largely caused by sporadic somatic gene mutations. This article aims to review and discuss current molecular signaling pathways and therapeutic targets for vascular malformations and to classify vascular malformations according to the molecular pathways involved. A literature review was performed using Embase and Medline. Different MeSH terms were combined for the search strategy, with the aim of encompassing all studies describing the classification, pathogenesis, and treatment of vascular malformations. Major pathways involved in the pathogenesis of vascular malformations are vascular endothelial growth factor (VEGF), Ras/Raf/MEK/ERK, angiopoietin-TIE2, transforming growth factor beta (TGF-β), and PI3K/AKT/mTOR. These pathways are involved in controlling cellular growth, apoptosis, differentiation, and proliferation, and play a central role in endothelial cell signaling and angiogenesis. Many vascular malformations share similar aberrant molecular signaling pathways with cancers and inflammatory disorders. Therefore, selective anticancer agents and immunosuppressants may be beneficial in treating vascular malformations of specific mutations. The current classification systems of vascular malformations, including the International Society of the Study of Vascular Anomalies (ISSVA) classification, are primarily observational and clinical, and are not based on the molecular pathways involved in the pathogenesis of the condition. Several molecular pathways with potential therapeutic targets have been demonstrated to contribute to the development of various vascular anomalies. Classifying vascular malformations based on their molecular pathogenesis may improve treatment by determining the underlying nature of the condition and their potential therapeutic target.

Current HHT genetic overview in Spain and its phenotypic correlation: data from RiHHTa registry

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular disease with autosomal dominant inheritance. Disease-causing variants in endoglin (ENG) and activin A receptor type II-like 1 (ACVRL1) genes are detected in more than 90% of cases submitted to molecular diagnosis.

METHODS

We used data from the RiHHTa (Computerized Registry of Hereditary Hemorrhagic Telangiectasia) registry to describe genetic variants and to assess their genotype-phenotype correlation among HHT patients in Spain.

RESULTS

By May 2019, 215 patients were included in the RiHHTa registry with a mean age of 52.5 ± 16.5 years and 136 (63.3%) were women. Definitive HHT diagnosis defined by the Curaçao criteria were met by 172 (80%) patients. Among 113 patients with genetic test, 77 (68.1%) showed a genetic variant in ACVRL1 and 36 (31.8%) in ENG gene. The identified genetic variants in ACVRL1 and ENG genes and their clinical significance are provided. ACVRL1 mutations were more frequently nonsense (50%) while ENG mutations were more frequently, frameshift (39.1%). ENG patients were significantly younger at diagnosis (36.9 vs 45.7 years) and had pulmonary arteriovenous malformations (AVMs) (71.4% vs 24.4%) and cerebral AVMs (17.6% vs 2%) more often than patients with ACVRL1 variants. Patients with ACVRL1 variants had a higher cardiac index (2.62 vs 3.46), higher levels of hepatic functional blood tests, and anemia (28.5% vs 56.7%) more often than ENG patients.

CONCLUSIONS

ACVRL1 variants are more frequent than ENG in Spain. ACVRL1 patients developed symptomatic liver disease and anemia more often than ENG patients. Compared to ACVRL1, those with ENG variants are younger at diagnosis and show pulmonary and cerebral AVMs more frequently.

Antithrombotic Therapy in Hereditary Hemorrhagic Telangiectasia: Real-World Data from the Gemelli Hospital HHT Registry

Although Hereditary Hemorrhagic Telangiectasia (HHT) is characterized by an overwhelming bleeding propensity, patients with this disease may also present medical conditions that require antithrombotic therapy (AT). However, precise information on indications, dosage, duration, effectiveness, and safety of AT in HHT patients is lacking. We performed a retrospective analysis of the HHT Registry of our University Hospital and found 26 patients who received AT for a total of 30 courses (19 courses of anticoagulant therapy and 11 courses of antiplatelet therapy). Indications to treatments included: atrial fibrillation, venous thrombosis and pulmonary embolism, heart valve replacement, retinal artery occlusion, secondary prevention after either stroke or myocardial infarction, and thromboprophylaxis for surgery. The total time of exposure to antiplatelet therapy was 385 months and to anticoagulant therapy 169 months. AT was generally well tolerated, with no fatal bleedings and no significant changes in hemoglobin levels. However, we found three major bleedings, with an incidence rate of 6.5 per 100 patients per year. When only patients treated with anticoagulants were considered, the incidence rate of major bleedings increased to 21.6 per 100 patients per year. Our study indicates that major bleeding may occur in HHT patients receiving AT, with a substantially increased rate in those treated with anticoagulants. Further studies are needed to fully estimate the tolerability of antithrombotic drugs in HHT.

Comparison of Ferumoxytol-enhanced MR Angiography and CT Angiography for the Detection of Pulmonary Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia: Initial Results

PURPOSE

To perform a preliminary comparison of the sensitivity and positive predictive value of ferumoxytol-enhanced MR angiography with those of CT angiography for detection of pulmonary arteriovenous malformations (AVMs) in hereditary hemorrhagic telangiectasia (HHT).

MATERIALS AND METHODS

Institutional review board approval and informed patient consent were obtained. Ten patients with pulmonary AVMs who had undergone CT of the chest within 12 months underwent MRI of the chest and abdomen with ferumoxytol at 3.0 T at a dose of 4 mg per kilogram of body weight. Consensus review of MR and CT images assessed the presence and characteristics of pulmonary AVMs, image quality, vessel visibility, and artifact grade.

RESULTS

Forty-three AVMs were detected, 13 native and 30 recanalized. Twenty-one AVMs had a feeding artery diameter of greater than 2 mm, of which detection occurred in 19 (at MRI and CT), in two (at MRI only), and zero (at CT only). Twenty-two AVMs had a feeding artery diameter of less than or equal to 2 mm, of which detection occurred in 16 (at MRI and CT), six (at CT only), and zero (at MRI only). For the entire cohort, the sensitivity of ferumoxytol-enhanced MRI using CT as the reference standard was 85.4% (35 of 41), and the positive predictive value was 100% (35 of 35). No significant difference was found between CT and MRI in AVM size, feeding artery and draining vein diameter, and artifact score (P >.05 for all).

CONCLUSION

Initial results suggest that ferumoxytol-enhanced MRI is a feasible alternative to CT for detection of pulmonary AVM in HHT, while avoiding repeated exposure to radiation, nephrotoxic contrast material, or gadolinium-based contrast agent.© RSNA, 2020.

Gender differences in hereditary hemorrhagic telangiectasia severity

Background

Gender differences in organ involvement and clinical severity have been poorly described in hereditary hemorrhagic telangiectasia (HHT). The aim of this study was to describe differences in the severity of HHT manifestations according to gender.

Methods

Severity was measured according to Epistaxis Severity Score (ESS), Simple Clinical Scoring Index for hepatic involvement, a general HHT-score, needing for invasive treatment (pulmonary or brain arteriovenous malformations -AVMs- embolization, liver transplantation or Young’s surgery) or the presence of adverse outcomes (severe anemia, emergency department -ED- or hospital admissions and mortality).

Results

One hundred forty-two (58.7%) women and 100 (41.3%) men were included with a mean age of 48.9 ± 16.6 and 49 ± 16.5 years, respectively. Women presented hepatic manifestations (7.1% vs 0%) and hepatic involvement (59.8% vs 47%), hepatic AVMs (28.2% vs 13%) and bile duct dilatation (4.9% vs 0%) at abdominal CT, and pulmonary AVMs at thoracic CT (35.2% vs 23%) more often than men. The Simple Clinical Scoring Index was higher in women (3.38 ± 1.2 vs 2.03 ± 1.2), and more men were considered at low risk of harboring clinically significant liver disease than women (61% vs 25.3%). These differences were mantained when considering HHT1 and HHT2 patients separetely. Duodenal telangiectasia were more frequent in men than women (21% vs 9.8%). Invasive treatments were more frequently needed in women (28.2% vs 16%) but men needed attention at the ED more often than women (48% vs 28.2%), with no differences in ESS, HHT-score, anemia hospital admissions or mortality.

Conclusions

HHT women showed more severe hepatic involvement than men, also among HHT1 and HHT2 patients. Women had higher prevalence of pulmonary AVMs and needed invasive procedures more frequently, while men needed attention at the ED more often. These data might help physicians to individualize HHT patients follow-up.

Novel mutation in ENG gene causing Hereditary Hemorrhagic Telangiectasia in a Peruvian family

Hereditary Hemorrhagic Telangiectasia (HHT) is a rare disorder of vascular development. Common manifestations include epistaxis, telangiectasias and arteriovenous malformations (AVMs) in multiple organs. Most patients have deletions or missense mutations in the ENG or ACVRL1 gene respectively, significantly affecting endothelium homeostasis. We analyzed the ENG gene in five members of a Peruvian family affected by HHT. One novel mutation was found in exon four of the ENG gene c.408delA, at aminoacid residue 136. This mutation changes the subsequent reading frame producing an early stop at residue 162, preserving only one fourth of the normal protein of 658 aa. This mutation was found in the four affected members of family.

Somatic mutations in intracranial arteriovenous malformations

Background

Intracranial arteriovenous malformation (AVM) is a common cause of primary intracerebral hemorrhage in young adults. Lesions typically are sporadic and contain somatic mutations in KRAS or BRAF. The purpose of this study was to identify somatic mutations in a cohort of participants with brain AVM and to determine if any genotype-phenotype associations exist.

Methods

Human brain AVM specimens (n = 16) were collected during a clinically-indicated procedure and subjected to multiplex targeted sequencing using molecular inversion probe (MIP-seq) for mutations in KRAS, BRAF, HRAS, NRAS, and MAP2K1. Endothelial cells (ECs) were separated from non-ECs by immune-affinity purification. Droplet digital PCR (ddPCR) was used to confirm mutations and to screen for mutations that may have been missed by MIP-seq. Patient and AVM characteristics were recorded.

Results

We detected somatic mutations in 10 of 16 specimens (63%). Eight had KRAS mutations [G12D (n = 5), G12V (n = 3)] and two had BRAF mutations [V600E (n = 1), Q636X (n = 1)]. We found no difference in age, sex, presenting symptom, AVM location, or AVM size between patients with a confirmed mutation and those without. Nor did we observe differences in these features between patients with KRAS or BRAF mutations. However, two patients with BRAF mutations presented at an older age than other study participants.

Conclusions

Somatic mutations in KRAS and, less commonly in BRAF, are found in many but not all intracranial AVM samples. Currently, there are no obvious genotype-phenotype correlations that can be used to predict whether a somatic mutation will be detected and, if so, which gene will be mutated.

CRISPR Diagnosis and Therapeutics with Single Base Pair Precision

Clustered regularly interspaced short palindromic repeats, or CRISPR, has been widely accepted as a versatile genome editing tool with significant potential for medical application. Reliable allele specificity is one of the most critical elements for successful application of this technology to develop high-precision therapeutics and diagnostics. CRISPR-based genome editing tools achieve high-fidelity distinction of single-base differences in target genomic loci by structural identification of CRISPR-associated (Cas) proteins and sequences of the guide RNAs. In this review, we describe the structural features of ribonucleoprotein complex formation by CRISPR proteins and guide RNAs that eventually recognize target DNA sequences. This structural understanding provides the basis for the recent applications of enhanced single-base precision genome editing technologies for effective distinction of specific alleles.

Epidemiology and Trends of Hereditary Hemorrhagic Telangiectasia in the United States

Background

To our knowledge, no national studies have investigated the epidemiology of hereditary hemorrhagic telangiectasia (HHT) in the United States since the incorporation of the International Statistical Classification of Diseases and Related Health Problems, 10th Revision, Clinical Modification (ICD-10 CM).

Objective

Our objective is to analyze the epidemiology of HHT from 2013 to 2017 and to determine the relationships between epistaxis and other associated complications of this rare disease.

Methods

We analyzed the epidemiology of HHT between 2013 and 2017 by accessing data of 87 709 738 patients from the Clinformatics Data Mart using ICD-9 CM and ICD-10 CM codes. Variables analyzed included age, gender, region, clinical setting of diagnosis, hospitalizations, and complications. Bivariate analyses using generalized linear models were conducted to determine the likelihood of HHT patients with epistaxis enduring associated life-threatening complications such as cerebral hemorrhage, thrombosis, and pulmonary hemorrhage compared to HHT patients without epistaxis during the study period.

Results

The prevalence of HHT increased from 6.1 to 12.1 per 100 000 persons, with patients of ages 18 to 29 years and those older than 60 years seeing the greatest percent increase. The prevalence of HHT in the Southern United States saw a 147% increase. Compared to HHT patients without epistaxis, HHT patients with epistaxis were 3.4 times more likely to experience pulmonary hemorrhage, 3.3 times more likely to have pulmonary emboli, 2.8 times more likely to experience cerebral hemorrhage, and 2.0 times more likely to have thrombosis during the study period.

Conclusion

Our national study has provided the first incidence and prevalence rates of HHT in the United States since the incorporation of the ICD-10 CM. HHT patients with epistaxis require prompt multidisciplinary treatment of their condition due to their increased risk of life-threatening complications.

SMAD4 Prevents Flow Induced Arteriovenous Malformations by Inhibiting Casein Kinase 2

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is an inherited vascular disorder that causes arteriovenous malformations (AVMs). Mutations in the genes encoding Endoglin ( ENG) and activin-receptor-like kinase 1 ( AVCRL1 encoding ALK1) cause HHT type 1 and 2, respectively. Mutations in the SMAD4 gene are present in families with juvenile polyposis-HHT syndrome that involves AVMs. SMAD4 is a downstream effector of transforming growth factor-β (TGFβ)/bone morphogenetic protein (BMP) family ligands that signal via activin-like kinase receptors (ALKs). Ligand-neutralizing antibodies or inducible, endothelial-specific Alk1 deletion induce AVMs in mouse models as a result of increased PI3K (phosphatidylinositol 3-kinase)/AKT (protein kinase B) signaling. Here we addressed if SMAD4 was required for BMP9-ALK1 effects on PI3K/AKT pathway activation.

METHODS

The authors generated tamoxifen-inducible, postnatal, endothelial-specific Smad4 mutant mice ( Smad4^iΔEC).

RESULTS

We found that loss of endothelial Smad4 resulted in AVM formation and lethality. AVMs formed in regions with high blood flow in developing retinas and other tissues. Mechanistically, BMP9 signaling antagonized flow-induced AKT activation in an ALK1- and SMAD4-dependent manner. Smad4^iΔEC endothelial cells in AVMs displayed increased PI3K/AKT signaling, and pharmacological PI3K inhibitors or endothelial Akt1 deletion both rescued AVM formation in Smad4^iΔEC mice. BMP9-induced SMAD4 inhibited casein kinase 2 ( CK2) transcription, in turn limiting PTEN phosphorylation and AKT activation. Consequently, CK2 inhibition prevented AVM formation in Smad4^iΔEC mice.

CONCLUSIONS

Our study reveals SMAD4 as an essential effector of BMP9-10/ALK1 signaling that affects AVM pathogenesis via regulation of CK2 expression and PI3K/AKT1 activation.

Intramuscular fast-flow vascular anomaly contains somatic MAP2K1 and KRAS mutations

BACKGROUND

The term "intramuscular hemangioma capillary type" (IHCT) refers to a fast-flow vascular lesion that is classified as a tumor, although its phenotype overlaps with arteriovenous malformation (AVM). The purpose of this study was to identify somatic mutations in IHCT.

METHODS

Affected tissue specimens were obtained during a clinically indicated procedure. The diagnosis of IHCT was based on history, physical examination, imaging and histopathology. Because somatic mutations in cancer-associated genes can cause vascular malformations, we sequenced exons from 446 cancer-related genes in DNA from 7 IHCT specimens. We then performed mutation-specific droplet digital PCR (ddPCR) to independently test for the presence of a somatic mutation found by sequencing and to screen one additional IHCT sample.

RESULTS

We detected somatic mutations in 6 of 8 IHCT specimens. Four specimens had a mutation in MAP2K1 (p.Q58_E62del, p.P105_I107delinsL, p.Q56P) and 2 specimens had mutations in KRAS (p.K5E and p.G12D, p.G12D and p.Q22R). Mutant allele frequencies detected by sequencing and confirmed by ddPCR ranged from 2 to 15%.

CONCLUSIONS

IHCT lesions are phenotypically similar to AVMs and contain the same somatic MAP2K1 or KRAS mutations, suggesting that IHCT is on the AVM spectrum. We propose calling this lesion "intramuscular fast-flow vascular anomaly."

Current Status of Clinical Diagnosis and Genetic Analysis of Hereditary Hemorrhagic Telangiectasia in South Korea: Multicenter Case Series and a Systematic Review

Purpose

Hereditary hemorrhagic telangiectasia (HHT), a rare genetic vascular disorder, has been rarely reported in South Korea. We investigated the current prevalence and presenting patterns of genetically confirmed HHT in South Korea.

Materials and Methods

We defined HHT patients as those with proven mutations on known HHT-related genes (ENG, ACVRL1, SMAD4, and GDF2) or those fulfilling 3 or 4 of the Curaçao criteria. A computerized systematic search was performed in PubMed and KoreaMed using the following search term: (“hereditary hemorrhagic telangiectasia” AND “Korea”) OR (“Osler-Weber-Rendu” AND “Korea”). We also collected government health insurance data. HHT genetic testing results were collected from three tertiary hospitals in which the genetic tests were performed. We integrated patient data by analyzing each case to obtain the prevalence and presenting pattern of HHT in South Korea.

Results

We extracted 90 cases from 52 relevant articles from PubMed and KoreaMed. An additional 22 cases were identified from the three Korean tertiary hospitals after excluding seven cases that overlapped with those in the published articles. Finally, 112 HHT patients were identified (41 males and 71 females, aged 4–82 years [mean±standard deviation, 45.3±20.6 years]). The prevalence of HHT in South Korea is about 1 in 500,000, with an almost equal prevalence among men and women. Forty-nine patients underwent genetic testing, of whom 28 had HHT1 (ENG mutation) and 19 had HHT2 (ACVRL1 mutation); the other two patients were negative for ENG, ACVRL1, and SMAD4 mutations.

Conclusion

The prevalence of HHT is underestimated in Korea. The rate of phenotypic presentation seems to be similar to that found worldwide. Korean health insurance coverage is limited to representative genetic analysis to detect ENG and ACVRL1 mutations. Further genetic analyses to detect HHT3, HHT4, and other forms of HHT should be implemented.

Bevacizumab as a treatment option in gastrointestinal bleeding associated to hereditary hemorrhagic telangiectasia. Case Report

Introduction: Hereditary Hemorrhagic Telangiectasia (HHT) is an autosomal dominant genetic disease characterized by the presence of arteriovenous malformations in the nasal mucosa, the tips of fingers, and sometimes in the lungs, the gastrointestinal tract, the liver, the pancreas, the marrow and the brain. Its treatment is based on symptomatic control measures, but recently, the administration of anti-vascular endothelial growth factor (VEGF) molecules has been proposed as a treatment alternative, especially in patients with recurrent bleeding.Case presentation: The case of a 67-year-old man diagnosed with HHT and suffering from potentially life-threatening gastrointestinal GI bleeding is presented. The patient underwent several esophagogastric cauterization procedures but not positive outcomes were obtained, so he had to go to the Emergency Service of the hospital multiple times due to having low levels of hemoglobin (as low as 3.5g/dl). A bevacizumab based treatment was started by using a novel dosage regimen consisting of the administration of 6 5mg/kg bevacizumab dosages every 14 days. During the first week of treatment, hemoglobin levels increased to 14g/dl and the condition was stabilized.Conclusions: The findings reported here suggest that bevacizumab may be a therapeutic choice to be considered when treating patients with recurrent and refractory GI bleeding caused by HHT. However, a larger sample is required to determine if administering this medication is safe for these patients, as well as the appropriate dosage.

Endoglin is a conserved regulator of vasculogenesis in zebrafish - implications for hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a progressive vascular disease with high mortality and prevalence. There is no effective treatment of HHT due to the lack of comprehensive knowledge of its underlying pathological mechanisms. The majority of HHT1 patients carry endoglin (ENG) mutations. Here, we used Danio rerio (zebrafish) as an in vivo model to investigate the effects of endoglin knockdown on vascular development. According to phylogenetic analyses and amino acid sequence similarity analyses, we confirmed that endoglin is conserved in vertebrates and descended from a single common ancestor. Endoglin is highly expressed in the vasculature beginning at the segmentation period in zebrafish. Upon endoglin knockdown by morpholinos, we observed disruption in the intersegmental vessels (ISVs) and decreased expression of several vascular markers. RNA sequencing (RNA-Seq) results implied that the BMP-binding endothelial regulator (bmper) is a gene affected by endoglin knockdown. Rescue experiments demonstrated that overexpression of bmper significantly increased the number of endothelial cells (ECs) and reduced the defects at ISVs in zebrafish. Moreover, there was enhanced tube formation in ENG mutant ECs derived from a HHT patient after human recombinant BMPER (hrBMPER) stimulation. Taken together, our results suggest that bmper, a potential downstream gene of ENG, could be targeted to improve vascular integrity in HHT.