Hereditary haemorrhagic telangiectasia: a population-based study of prevalence and mortality in Danish patients

Approach to anaemia in gastrointestinal disease: A position paper by the ESPGHAN Gastroenterology Committee

Anaemia is a frequent consequence of many gastrointestinal (GI) diseases in children and it can even be the initial presenting symptom of underlying chronic GI disease. The definition of anaemia is age and gender-dependent and it can be classified based on pathophysiology, red cell morphology, and clinical presentation. Although nutritional deficiencies, including GI malabsorption of nutrients and GI bleeding, play a major role, other pathophysiologic mechanisms seen in chronic GI diseases, whether inflammatory (e.g., inflammatory bowel disease) or not (e.g., coeliac disease and dysmotility), are causing anaemia. Drugs, such as proton pump inhibitors, mesalamine, methotrexate and sulfasalazine, are also a potential cause of anaemia. Not uncommonly, due to a combination of factors, such as iron deficiency and a chronic inflammatory state, the underlying pathophysiology may be difficult to decipher and a broad diagnostic work-up is required. The goal of treatment is correction of anaemia by supplementation of iron and vitamins. The first therapeutic step is to treat the underlying cause of anaemia including bleeding control, restoration of intestinal integrity and reduction of inflammatory burden. The route of iron and vitamin supplementation is guided by the severity of anaemia.

Hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait and caused by loss-of-function pathogenic variants in genes encoding proteins of the BMP signalling pathway. Up to 90% of disease-causal variants are observed in ENG and ACVRL1, with SMAD4 and GDF2 less frequently responsible for HHT. In adults, the most frequent HHT manifestations relate to iron deficiency and anaemia owing to recurrent epistaxis (nosebleeds) or bleeding from gastrointestinal telangiectases. Arteriovenous malformations (AVMs) in the lungs, liver and the central nervous system cause additional major complications and often complex symptoms, primarily due to vascular shunting, which is right-to-left through pulmonary AVMs (causing ischaemic stroke or cerebral abscess) and left-to-right through systemic AVMs (causing high cardiac output). Children usually experience isolated epistaxis; in rare cases, childhood complications occur from large AVMs in the lungs or central nervous system. Management goals encompass control of epistaxis and intestinal bleeding from telangiectases, screening for and treatment of iron deficiency (with or without anaemia) and AVMs, genetic counselling and evaluation of at-risk family members. Novel therapeutics, such as systemic antiangiogenic therapies, are actively being investigated. Although HHT is associated with increased morbidity, the appropriate screening and treatment of visceral AVMs, and the effective management of bleeding and anaemia, improves quality of life and overall survival.

Reperfusion of Pulmonary Arteriovenous Malformations Treated by Catheter Embolization

Objective: The aim of this study was to evaluate patients with hereditary hemorrhagic telangiectasia (HHT) for the potential reperfusion of pulmonary arteriovenous malformations (PAVM) treated by catheter embolization using coils or embolization plugs and to analyze causes of possible reperfusion in order to further improve treatment. Methods: This retrospective study analyzed the data of 345 patients who underwent screening for pulmonary arteriovenous malformations in cases of suspected or confirmed HHT (Osler's disease). Of these, 118 patients with PAVM that underwent catheter embolization and had at least one follow-up study were included in our study and evaluated for potential reperfusion. Screening and follow-up for the detection of PAVM was performed by dynamic and high-resolution contrast-enhanced magnetic resonance angiography (MRA). The average follow-up time was 6.2 years. Results: Reperfusion was detected in 43 of 118 patients at follow-up. Thirty-five of these patients showed a recanalization of the treated vessel and in eleven patients the formation of collateral vessels resupplying the PAVM were identified as the cause of reperfusion. The average time between embolization and detected reperfusion was 5.6 years. The recanalization of both coils and plugs was observed. The recanalization of coils could be attributed in most cases to an insufficient packing density of the implanted coils. In addition, an enlarged diameter of the feeding artery was confirmed as a risk factor for reperfusion. Conclusions: As the reperfusion of embolized pulmonary arteriovenous malformations can occur after a long time interval post-treatment, regular lifelong follow-up studies after embolization are essential to detect reperfusion at an early stage and avoid serious complications like a brain abscess or stroke through prompt re-embolization. After coil embolization, attention should be paid to sufficiently dense packing to achieve adequate and permanent occlusion.

2024 Guideline for the Primary Prevention of Stroke: A Guideline From the American Heart Association/American Stroke Association

AIM

The "2024 Guideline for the Primary Prevention of Stroke" replaces the 2014 "Guidelines for the Primary Prevention of Stroke." This updated guideline is intended to be a resource for clinicians to use to guide various prevention strategies for individuals with no history of stroke.

METHODS

A comprehensive search for literature published since the 2014 guideline; derived from research involving human participants published in English; and indexed in MEDLINE, PubMed, Cochrane Library, and other selected and relevant databases was conducted between May and November 2023. Other documents on related subject matter previously published by the American Heart Association were also reviewed.

STRUCTURE

Ischemic and hemorrhagic strokes lead to significant disability but, most important, are preventable. The 2024 primary prevention of stroke guideline provides recommendations based on current evidence for strategies to prevent stroke throughout the life span. These recommendations align with the American Heart Association's Life's Essential 8 for optimizing cardiovascular and brain health, in addition to preventing incident stroke. We also have added sex-specific recommendations for screening and prevention of stroke, which are new compared with the 2014 guideline. Many recommendations for similar risk factor prevention were updated, new topics were reviewed, and recommendations were created when supported by sufficient-quality published data.

Cholangitis and Congestive Heart Failure Secondary to Biliary Hemorrhage in Hereditary Hemorrhagic Telangiectasia

This case report discusses the case of a 74-year-old man who was diagnosed with hereditary hemorrhagic telangiectasia (HHT). The patient initially presented with right upper quadrant abdominal pain and was later diagnosed with cholangitis. Subsequently, heart failure was identified due to hepatic arteriovenous malformations. Although the exact duration of his disease remains unclear, the patient was initially asymptomatic and developed significant complications over time, possibly reflecting the progressive nature of vascular malformations associated with HHT. This case underscores the necessity of regular imaging follow-ups to assess the progression of vascular malformations in various organs, highlighting the clinical significance of the early detection and management of complications in HHT.

Arterial Spin-Labeling MR Imaging in the Detection of Intracranial Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia

BACKGROUND AND PURPOSE

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease that causes vascular malformations in a variety of organs and tissues, including brain AVMs. Because brain AVMs have the potential to cause disabling or fatal intracranial hemorrhage, detection of these lesions before rupture is the goal of screening MR imaging/MRA examinations in patients with HHT. Prior studies have demonstrated superior sensitivity for HHT-related brain AVMs by using postcontrast MR imaging sequences as compared with MRA alone. We now present data regarding the incremental benefit of including arterial spin-labeling (ASL) perfusion sequences as part of MR imaging/MRA screening in patients with this condition.

MATERIALS AND METHODS

We retrospectively analyzed 831 patients at the UCSF Hereditary Hemorrhagic Telangiectasia Center of Excellence. Of these, 42 patients had complete MR imaging/MRA, ASL perfusion scans, and criterion-standard DSA data. Two neuroradiologists reviewed imaging studies and a third provided adjudication when needed.

RESULTS

Eight patients had no brain AVMs detected on DSA. The remaining 34 patients had 57 brain AVMs on DSA. Of the 57 identified AVMs, 51 (89.5%) were detected on ASL and 43 (75.4%) were detected on conventional MR imaging/MRA sequences (P = .049), with 8 lesions detected on ASL perfusion but not on conventional MR imaging.

CONCLUSIONS

ASL provides increased sensitivity for brain AVMs in patients with HHT. Inclusion of ASL should be considered as part of comprehensive MR imaging/MRA screening protocols for institutions taking care of patients with HHT.

A rare case of spinal involvement in hereditary hemorrhagic telangiectasia

INTRODUCTION

Here, we describe a rare case of a spinal arteriovenous fistula in a patient with known hereditary hemorrhagic telangiectasia (HHT) and spontaneous intraspinal hemorrhage. Furthermore, we provide a brief review of the literature on the formation of spinal arteriovenous malformations (AVM) in relation to this disease.

CASE PRESENTATION

The case involves a 54-year-old male with known HHT. At the age of 49, the patient experienced recurrent cystitis. Urological evaluation ruled the cause to be neurological and subsequent imaging revealed a thoracic AVM. Four years later, the patient was admitted to A&E with chest pain and loss of function of the lower extremities and right arm, suspicious for ruptured aortic dissection. Trauma-CT excluded this and a final diagnosis of ruptured spinal AVM was made. Seven months post-injury, a spinal angiography was performed confirming the AVM. The remaining AVM was embolized under general anesthesia with acceptable results.

DISCUSSION

Spinal involvement in HHT is exceedingly rare but remains an important differential diagnosis, especially when patients present autonomic symptoms as these could potentially progress to life-threatening complications. The literature and the presented case indicate the prudence of closing spinal AVMs in HHT in case of symptoms, including autonomic, such as bladder dysfunction.

Investigation of the Genetic Determinants of Telangiectasia and Solid Organ Arteriovenous Malformation Formation in Hereditary Hemorrhagic Telangiectasia (HHT)

Telangiectases and arteriovenous malformations (AVMs) are the characteristic lesions of Hereditary Hemorrhagic Telangiectasia (HHT). Somatic second-hit loss-of-function variations in the HHT causative genes, ENG and ACVRL1, have been described in dermal telangiectasias. It is unclear if somatic second-hit mutations also cause the formation of AVMs and nasal telangiectasias in HHT. To investigate the genetic mechanism of AVM formation in HHT, we evaluated multiple affected tissues from fourteen individuals. DNA was extracted from fresh/frozen tissue of 15 nasal telangiectasia, 4 dermal telangiectasia, and 9 normal control tissue biopsies, from nine unrelated individuals with HHT. DNA from six formalin-fixed paraffin-embedded (FFPE) AVM tissues (brain, lung, liver, and gallbladder) from five individuals was evaluated. A 736 vascular malformation and cancer gene next-generation sequencing (NGS) panel was used to evaluate these tissues down to 1% somatic mosaicism. Somatic second-hit mutations were identified in three in four AVM biopsies (75%) or half of the FFPE (50%) samples, including the loss of heterozygosity in ENG in one brain AVM sample, in which the germline mutation occurred in a different allele than a nearby somatic mutation (both are loss-of-function mutations). Eight of nine (88.9%) patients in whom telangiectasia tissues were evaluated had a somatic mutation ranging from 0.68 to 1.96% in the same gene with the germline mutation. Six of fifteen (40%) nasal and two of four (50%) dermal telangiectasia had a detectable somatic second hit. Additional low-level somatic mutations in other genes were identified in several telangiectasias. This is the first report that nasal telangiectasias and solid organ AVMs in HHT are caused by very-low-level somatic biallelic second-hit mutations.

Hereditary hemorrhagic telangiectasia diagnosis: A case report

This case report presents a 13-year-old patient with a lung nodule identified on a chest radiograph in the emergency department during an evaluation of knee and side pain after a fall. The patient had nosebleeds, family history of hereditary hemorrhagic telangiectasia (HHT) and after chest computed tomography with angiography, the nodule was defined as a single pulmonary arteriovenous malformation (PAVM). Neither parent nor patient had been evaluated for HHT, an autosomal dominant disease, despite the family history. This patient satisfied the clinical criteria for the diagnosis and had a confirmatory genetic test, which led to diagnosis in mother also. The patient's PAVMs were treated, decreasing the risk of life threatening complications. Diagnosing HHT in children is often delayed or missed, even in families with HHT, as in this case report. Without any physical signs or clinical symptoms, families and healthcare providers often dismiss the possibility of the diagnosis. Children with HHT are at the same risk for complications of stroke, anemia, hypoxemia, heart failure and increased morbidity as adults. It is essential to recognize the importance of family history when evaluating children in primary care and urgent settings, as this patient's diagnosis was delayed 13 years. Awareness of HHT signs and symptoms are essential to early referral to an HHT specialist, for diagnosis and management.

Increased Risk for Infections and Allergic Disease in Hereditary Hemorrhagic Telangiectasia

Background/Objectives: Hereditary hemorrhagic telangiectasia (HHT) is a rare disorder characterized by dilated blood vessels. Different immunological changes have been described in these patients. In this study, the predisposition of patients with HHT to infections and allergic diseases was assessed. Methods: Patients with HHT completed an online survey in English or German. Their data were compared to non-affected partners or friends. Results: A total of 430 out of 588 respondents with HHT answered our questions about infections and allergies. Patients with HHT suffered significantly more often from various types of allergies than their partners, especially type I allergies (n = 226/276, 82%), and had a higher risk for sinusitis, urinary tract infections, pulmonary infections, and abscesses. A total of 38% of the patients took antibiotics prior to dental or surgical procedures (n = 57/152), and, in 10% of these patients, pulmonary arteriovenous malformations (PAVMs) were not detected. On the other hand, 51% of patients with PAVM did not report a prophylactic antibiotic intake (n = 40/79). The patients who needed iron supplementations suffered more often from sepsis (OR: 9.00, 95%CI: 0.92-88.16). Conclusions: Compared to their non-affected controls, patients with HHT showed an increased risk for infections in different organs and allergic diseases. There is a need for campaigns raising greater awareness recommending prophylactic antibiotic intake in patients with PAVM.

Cost-effectiveness of bevacizumab therapy in the care of patients with hereditary hemorrhagic telangiectasia

ABSTRACT

No US Food and Drug Administration- or European Medicines Agency-approved therapies exist for bleeding due to hereditary hemorrhagic telangiectasia (HHT), the second-most common inherited bleeding disorder worldwide. The current standard of care (SOC) includes iron and red cell supplementation, alongside the necessary hemostatic procedures, none of which target underlying disease pathogenesis. Recent evidence has demonstrated that bleeding pathophysiology is amenable to systemic antiangiogenic therapy with the anti-vascular endothelial growth factor bevacizumab. Despite its high cost, the addition of longitudinal bevacizumab to the current SOC may reduce overall health care resource use and improve patient quality of life. We conducted, to our knowledge, the first cost-effectiveness analysis of IV bevacizumab in patients with HHT with the moderate-to-severe phenotype, comparing bevacizumab added to SOC vs SOC alone. The primary outcome was the incremental net monetary benefit (iNMB) reported over a lifetime time horizon and across accepted willingness-to-pay thresholds, in US dollar per quality-adjusted life year (QALY). Bevacizumab therapy accrued 9.3 QALYs while generating $428 000 in costs, compared with 8.3 QALYs and $699 000 in costs accrued in the SOC strategy. The iNMB of bevacizumab therapy vs the SOC was $433 000. No parameter variation and no scenario analysis, including choice of iron supplementation product, changed the outcome of bevacizumab being a cost-saving strategy. Bevacizumab therapy also saved patients an average of 133 hours spent receiving HHT-specific care per year of life. In probabilistic sensitivity analysis, bevacizumab was favored in 100% of all 10 000 Monte Carlo iterations across base-case and all scenario analyses. Bevacizumab should be considered for more favorable formulary placement in the care of patients with moderate-to-severe HHT.

Endothelial-to-Mesenchymal Transition in an Hereditary Hemorrhagic Telangiectasia-like Pediatric Case of Multiple Pulmonary Arteriovenous Malformations

Pulmonary arteriovenous malformations (PAVMs) are vascular anomalies resulting in abnormal connections between pulmonary arteries and veins. In 80% of cases, PAVMs are present from birth, but clinical manifestations are rarely seen in childhood. These congenital malformations are typically associated with Hereditary Hemorrhagic Telangiectasia (HHT), a rare disease that affects 1 in 5000/8000 individuals. HHT disease is frequently caused by mutations in genes involved in the TGF-β pathway. However, approximately 15% of patients do not have a genetic diagnosis and, among the genetically diagnosed, more than 33% do not meet the Curaçao criteria. This makes clinical diagnosis even more challenging in the pediatric age group. Here, we introduce an 8-year-old patient bearing a severe phenotype of multiple diffuse PAVMs caused by an unknown mutation which ended in lung transplantation. Phenotypically, the case under study follows a molecular pattern which is HHT-like. Therefore, molecular- biological and cellular-functional analyses have been performed in primary endothelial cells (ECs) isolated from the explanted lung. The findings revealed a loss of functionality in lung endothelial tissue and a stimulation of endothelial-to-mesenchymal transition. Understanding the molecular basis of this transition could potentially offer new therapeutic strategies to delay lung transplantation in severe cases.

Pulmonary arteriovenous malformations in Rendu-Osler-Weber syndrome

Rendu-Osler-Weber syndrome, also known as hereditary hemorrhagic telangiectasia, is an autosomal dominant hereditary disorder. It is characterized by presence of multiple arteriovenous malformations (AVMs) and telangiectasias. This article reports two cases of patients with Rendu-Osler-Weber syndrome who had pulmonary AVMs and underwent successful endovascular treatment. A brief review of the literature shows that up to 50% of patients with the syndrome have pulmonary AVMs and there is usually a positive family history in these patients. These pulmonary AVMs are multiple in 30% of cases and are associated with the most severe disease complications. Most patients are asymptomatic, even in the presence of AVMs with right-left shunts. When these shunts exceed 25% of the total blood volume, dyspnea, cyanosis, digital clubbing, and extracardiac murmurs may occur. Endovascular treatment is safe and offers control of complications from hereditary hemorrhagic telangiectasia and is currently the treatment of choice for these lesions.

Surgery or No Surgery? Exploring the Dilemma of Epistaxis Management in Patients with HHT

Background: Epistaxis, particularly in Hereditary Hemorrhagic Telangiectasia (HHT) patients, is a common otolaryngological emergency, often requiring complex management. A hierarchy of increasingly invasive interventions, from external compression of the nasal pyramid to nostril closure, is typically proposed and applied. Methods: We conducted a retrospective study on HHT patients to assess the effectiveness and longevity of invasive procedures postoperatively. Data were collected using the Epistaxis Severity Score (ESS) questionnaire. The primary focus was on changes in the frequency and intensity of epistaxis, while the secondary focus was on the overall quality of life. Results: This study found that invasive procedures initially improved the frequency and intensity of epistaxis in HHT patients. However, within 1 to 9 months postoperatively, these benefits often diminished, with hemorrhagic symptoms recurring at similar or worsened levels. Conclusions: The findings suggest a need for a cautious and restrained approach to using invasive treatments in managing epistaxis in HHT patients. Highly invasive procedures should be reserved for cases where less invasive methods fail, due to their temporary effectiveness and the risk of causing anatomical-functional changes in the rhino-sinus area, complicating future management of severe epistaxis.

High risk of ischaemic stroke amongst patients with hereditary haemorrhagic telangiectasia

BACKGROUND AND PURPOSE

Hereditary haemorrhagic telangiectasia (HHT) is a genetic disease with fragile blood vessels and vascular malformations, potentially causing neurological manifestations, including stroke and cerebral abscesses. The study aimed to investigate neurological manifestations in the Danish HHT database, focusing on pulmonary arteriovenous malformations (PAVMs) as a risk factor for cerebral events.

METHODS

Retrospective analysis of the Danish HHT database was conducted, cross-referencing neurological outcomes with the Danish Apoplexy Register for accuracy. Patients were stratified by HHT type. Primary outcomes included ischaemic stroke, transient ischaemic attack and cerebral haemorrhage. Secondary outcomes comprised age, age at HHT diagnosis, age at cerebral ischaemic event, and PAVM and cerebral arteriovenous malformation status.

RESULTS

Six hundred and sixty-four HHT patients were included. PAVM was diagnosed in 54% of patients, with higher prevalence in HHT type 1 (70%) compared to HHT type 2 (34%) and juvenile polyposis HHT (66%). Ischaemic stroke or transient ischaemic attack occurred in 12.5%, with a higher risk associated with macroscopic PAVM. Logistic regression showed a nearly 10 times increased risk of ischaemic stroke with macroscopic PAVM. Cerebral abscesses occurred in 3.2% of patients, all with macroscopic PAVM. Incomplete PAVM closure increased cerebral abscess risk.

CONCLUSION

This study provides valuable insights into the prevalence of neurological manifestations and vascular events in HHT patients. The presence of PAVM was associated with an increased risk of ischaemic stroke, highlighting the importance of early screening and intervention. The findings emphasize the need for comprehensive management strategies targeting both vascular and neurological complications in HHT patients, especially regarding secondary stroke prevention.

Elevated FVIII levels in hereditary hemorrhagic telangiectasia: Implications for clinical management

Objectives

The objective of this study was twofold: to determine the prevalence of arterial and venous thromboembolic events in the Norwegian Hereditary Hemorrhagic Telangiectasia (HHT) population, and to explore potential factors linked to such events, with particular emphasis on FVIII.

Methods

Patients with an HHT diagnosis attending the Otorhinolaryngology Department at Oslo University Hospital-Rikshospitalet were included consecutively between April 2021 and November 2022. We recorded the participants' medical history with an emphasis on thromboembolic events. Measurements of blood constituents, including FVIII, FIX, vWF, hemoglobin, iron, ferritin, and CRP were performed.

Results

One hundred and thirty-four patients were included in the study. The total prevalence of thromboembolic events among the participants was 23.1%. FVIII levels were high (>150 IU/dL) in the majority of HHT patients (n = 84) (68.3%) and were significantly associated with thromboembolic events (p < .001), as was age. Of the patients with high FVIII levels, 28 (33%) had experienced a thromboembolic event. Furthermore, FVIII levels were measured consecutively in 51 patients and were found to fluctuate above or below 150 IU/dL in 25% of these cases.

Conclusion

Thromboembolic events are highly prevalent in the Norwegian HHT population and are significantly associated with FVIII levels. FVIII levels can fluctuate, and measurements should be repeated in HHT patients to assess the risk of thromboembolic events.

Level of Evidence

4.

A novel frameshift mutation of the endoglin(ENG) gene causes hereditary hemorrhagic telangiectasia in a Chinese family

PURPOSE

Hereditary hemorrhagic telangiectasia (HHT) is a dominantly inherited disorder that involves epistaxis, mucocutaneous telangiectases, and visceral arteriovenous malformations (AVMs). This study aims to investigate the genetic causes in a Chinese family with HHT.

METHODS

HHT was confirmed according to Curaçao's diagnostic criteria. Three patients diagnosed with HHT and healthy members were recruited. Whole-exome sequencing (WES) and sanger sequencing were performed to define the patient's genetically pathogenic factor.

RESULTS

The proband presented with recurrent epistaxis, hepatopulmonary arteriovenous malformation, and adenocarcinoma. A novel frameshift mutation (c.1376_1377delAC, p.H459Lfs*41) of the ENG gene was revealed in affected individuals by WES. There was no report of this variant and predicted to be highly damaging by causing truncation of the ENG protein.

CONCLUSION

We report a novel variant in the ENG gene in Chinese that extends the mutational and phenotypic spectra of the ENG gene, and also demonstrates the feasibility of WES in the application of genetic diagnosis of HHT.

Pathogenic Variant Frequencies in Hereditary Haemorrhagic Telangiectasia Support Clinical Evidence of Protection from Myocardial Infarction

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia inherited as an autosomal dominant trait, due to a single heterozygous loss-of-function variant, usually in ACVRL1 (encoding activin receptor-like kinase 1 [ALK1]), ENG (encoding endoglin [CD105]), or SMAD4. In a consecutive single-centre series of 37 positive clinical genetic tests performed in 2021-2023, a skewed distribution pattern was noted, with 30 of 32 variants reported only once, but ACVRL1 c.1231C>T (p.Arg411Trp) identified as the disease-causal gene in five different HHT families. In the same centre's non-overlapping 1992-2020 series where 110/134 (82.1%) HHT-causal variants were reported only once, ACVRL1 c.1231C>T (p.Arg411Trp) was identified in nine further families. In a 14-country, four-continent HHT Mutation Database where 181/250 (72.4%) HHT-causal variants were reported only once, ACVRL1 c.1231C>T (p.Arg411Trp) was reported by 12 different laboratories, the adjacent ACVRL1 c.1232G>A (p.Arg411Gln) by 14, and ACVRL1 c.1120C>T (p.Arg374Trp) by 18. Unlike the majority of HHT-causal ACVRL1 variants, these encode ALK1 protein that reaches the endothelial cell surface but fails to signal. Six variants of this type were present in the three series and were reported 6.8-25.5 (mean 8.9) times more frequently than the other ACVRL1 missense variants (all p-values < 0.0039). Noting lower rates of myocardial infarction reported in HHT, we explore potential mechanisms, including a selective paradigm relevant to ALK1's role in the initiating event of atherosclerosis, where a plausible dominant negative effect of these specific variants can be proposed. In conclusion, there is an ~9-fold excess of kinase-inactive, cell surface-expressed ACVRL1/ALK1 pathogenic missense variants in HHT. The findings support further examination of differential clinical and cellular phenotypes by HHT causal gene molecular subtypes.

Pharmacogenomic Considerations for Anticoagulant Prescription in Patients with Hereditary Haemorrhagic Telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) is a vascular dysplasia that commonly results in bleeding but with frequent indications for therapeutic anticoagulation. Our aims were to advance the understanding of drug-specific intolerance and evaluate if there was an indication for pharmacogenomic testing. Genes encoding proteins involved in the absorption, distribution, metabolism, and excretion of warfarin, heparin, and direct oral anticoagulants (DOACs) apixaban, rivaroxaban, edoxaban, and dabigatran were identified and examined. Linkage disequilibrium with HHT genes was excluded, before variants within these genes were examined following whole genome sequencing of general and HHT populations. The 44 genes identified included 5/17 actionable pharmacogenes with guidelines. The 76,156 participants in the Genome Aggregation Database v3.1.2 had 28,446 variants, including 9668 missense substitutions and 1076 predicted loss-of-function (frameshift, nonsense, and consensus splice site) variants, i.e., approximately 1 in 7.9 individuals had a missense substitution, and 1 in 71 had a loss-of-function variant. Focusing on the 17 genes relevant to usually preferred DOACs, similar variant profiles were identified in HHT patients. With HHT patients at particular risk of haemorrhage when undergoing anticoagulant treatment, we explore how pre-emptive pharmacogenomic testing, alongside HHT gene testing, may prove beneficial in reducing the risk of bleeding and conclude that HHT patients are well placed to be at the vanguard of personalised prescribing.

Oral manifestations and dental considerations of patients with hereditary hemorrhagic telangiectasia: a scoping review

OBJECTIVE

We examined the range, nature, and extent of research conducted regarding the oral and dental implications of hereditary hemorrhagic telangiectasia (HHT) to identify gaps in the research and knowledge of the field.

STUDY DESIGN

We performed a scoping review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews and 2017 Guidance for the Conduct of Joanna Briggs Institute Scoping Reviews. We searched the MEDLINE and Web of Science databases for all full-text articles published in English from December 1946 to October 2022.

RESULTS

We identified 103 articles describing oral and dental considerations of patients with HHT, primarily case reports. Most reported oral telangiectasias of the tongue, lips, and palate. Many reported management of bleeding and the use or recommendation of prophylactic antibiotics before dental procedures.

CONCLUSIONS

Oral telangiectasias are commonly found in patients with hereditary hemorrhagic telangiectasia, and dental professionals may be the first to diagnose it in their patients. Early detection and diagnosis are important to prevent potentially fatal outcomes, and prophylactic antibiotics before procedures may be warranted.

The bleeding diathesis in patients with hereditary haemorrhagic telangiectasia is not due to impaired platelet function

BACKGROUND

Patients with the rare disease; Hereditary haemorrhagic telangiectasia (HHT) often bleed from telangiectatic lesions in mucosal surfaces. Studies suggest that impaired platelet function may also play a role in their bleeding tendency. The aim of the present study was to investigate whether HHT-patients with epistaxis have impaired platelet function.

METHOD

We conducted a case-control study based on a sample size calculation and included 22 HHT-patients (inclusion criteria: epistaxis severity score ≥ 4, no intake of medicine affecting platelet function the last 5 days, HHT-type 1 or 2, age ≥ 18 years) and 20 controls. We assessed the platelet function with standard haemostasis parameters, flow cytometry (platelet function and micro aggregation), rotational thromboelastometry and Platelet Function Analyzer 200.

RESULTS

We found no significant difference in mean platelet volume and immature platelet fraction and no difference in platelet activation as measured by exposure of CD62P, CD63P and PAC1 binding. Nor did we find a significant difference in platelet aggregation response in HHT-patients compared with the control group for all agonists (thrombin receptor activating peptide, adenosine diphosphate and collagen-related peptide). The PFA-200 analysis was without difference between the two groups and thromboelastometry showed no impairment of global haemostasis.

CONCLUSION

Reduced platelet function is unlikely to contribute to the frequent and long bleeding episodes that HHT-patients suffer from. We propose that further studies should focus on whether patients with HHT have hypercoagulability.

Hereditary hemorrhagic telangiectasia involving portal venous system: A case report and review of the literature

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant genetic disorder with an incidence of approximately 1 in 5000 in the general population. It is characterized by vasodilation, which affects specific organs, such as the skin, mucous membranes, brain, lungs, gastrointestinal tract, liver, and others. However, HHT rarely involves the portal venous system to cause serious clinical complications.

CASE SUMMARY

A 68-year-old woman was admitted to the emergency department due to four consecutive days of abdominal pain and bloody stool and was subsequently diagnosed with HHT. Computed tomography angiography confirmed the presence of an arteriovenous fistula (AVFs). Considering this specific manifestation, whole exome sequencing was performed. After a comprehensive evaluation, a selective superior mesenteric artery embolization was prioritized to avoid intestinal ischemia. The postoperative symptoms of the patient were quickly relieved. Unfortunately, two months post-procedure the patient died from intestinal necrosis and abdominal infection related to remaining AVFs.

CONCLUSION

For patients with diffuse superior mesenteric AVFs, selective mesenteric arterial embolization may lead to positive short-term outcomes.

Prevalence and risk factors for bleeding in hereditary hemorrhagic telangiectasia: a National Inpatient Sample study

Hereditary hemorrhagic telangiectasia (HHT) is a common bleeding disorder, but little is known regarding prevalence and risk factors for bleeding. Adult discharges with HHT and bleeding were identified by International Classification of Disease, 10th edition (ICD-10) codes in the National Inpatient Sample (NIS), 2016-2018. Prevalence estimates were weighted using NIS discharge-level weights to reflect national estimates. Risk factors for bleeding were determined by weighted multivariable logistic regression. Among 18 170 849 discharges, 2528 (0.01%) had HHT, of whom 648 (25.6%) had bleeding. Arteriovenous malformation (AVM) (31.9% vs 1.3%), angiodysplasia (23.5% vs 2.3%), telangiectasia (2.3% vs 0.2%), and epistaxis (17.9% vs 0.6%) were more common in HHT than in non-HHT patients (non-HHT), each P < .001. In contrast, menstrual (HMB) and postpartum bleeding (PPH) were less common in reproductive-age HHT than non-HHT, each P < .001. Anemia associated with iron deficiency (IDA), was equally common in HHT with or without bleeding (15.7% vs 16.0%), but more common than in non-HHT (7.5%), P < .001. Comorbidities, including gastroesophageal reflux (25.9% vs 20.0%) and cirrhosis (10.0% vs 3.6%) were greater in HHT than non-HHT, each P < .001. In multivariable logistic regression, peptic ulcer disease (OR, 8.86; P < .001), portal vein thrombosis (OR, 3.68; P = .006), and hepatitis C, (OR, 2.13; P = .017) were significantly associated with bleeding in HHT. In conclusion, AVM and angiodysplasia are more common and HMB and PPH less common in patients in those with HHT than non-HHT. IDA deficiency is as common in HHT with and without bleeding, suggesting ongoing blood loss and need for universal iron screening.

Multi-organ hereditary hemorrhagic telangiectasia: A case report

BACKGROUND

Type 2 hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disease and is associated with ALK1 gene mutations. Type 2 HHT patients primarily suffer from recurrent bleeding. There is currently no promising treatment.

CASE SUMMARY

A 5-year-old Chinese patient (III23) was admitted to Zhongshan Hospital for recurrent melena occurring over 2 mo. She had been experiencing epistaxis for years and had been diagnosed with idiopathic pulmonary hypertension 4 mo before presentation. Abdominal computed tomography examination showed hepatic arteriovenous malformation. Gene testing revealed a c.1121G>A mutation on the ALK1 gene. According to the international diagnostic criteria, this patient was diagnosed with HHT. In addition, 8 more family members exhibited HHT symptoms to varying degrees. Gene testing in 5 family members (2 with HHT symptoms and 3 without HHT symptoms) revealed the ALK1 c.1121G>A mutation in the 2 family members with HHT symptoms. This missense mutation results in the substitution of arginine for glutamine at amino acid position 374 (R374Q) in the conserved functional kinase domain of ALK1. Biological studies revealed that this mutation decreased the kinase activity of ALK1 and impeded the phosphorylation of its substrate Smad1. Moreover, the R374Q mutant downregulated the protein level of collagen-1, a fibrogenic factor, indicating abnormal fiber generation during vascular formation.

CONCLUSION

The R374Q mutant of ALK1 and its subsequent influence on fiber generation highly indicated its pathogenic role in this family with type 2 HHT. Detection of this gene mutation will facilitate early diagnosis of suspected type 2 HHT patients, and mechanistic studies will provide insights for future therapy.

ANG2 Blockade Diminishes Proangiogenic Cerebrovascular Defects Associated With Models of Hereditary Hemorrhagic Telangiectasia

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a vascular disorder characterized by arteriovenous malformations and blood vessel enlargements. However, there are no effective drug therapies to combat arteriovenous malformation formation in patients with HHT. Here, we aimed to address whether elevated levels of ANG2 (angiopoietin-2) in the endothelium is a conserved feature in mouse models of the 3 major forms of HHT that could be neutralized to treat brain arteriovenous malformations and associated vascular defects. In addition, we sought to identify the angiogenic molecular signature linked to HHT.

METHODS

Cerebrovascular defects, including arteriovenous malformations and increased vessel calibers, were characterized in mouse models of the 3 common forms of HHT using transcriptomic and dye injection labeling methods.

RESULTS

Comparative RNA sequencing analyses of isolated brain endothelial cells revealed a common, but unique proangiogenic transcriptional program associated with HHT. This included a consistent upregulation in cerebrovascular expression of ANG2 and downregulation of its receptor Tyr kinase with Ig and EGF homology domains (TIE2/TEK) in HHT mice compared with controls. Furthermore, in vitro experiments revealed TEK signaling activity was hampered in an HHT setting. Pharmacological blockade of ANG2 improved brain vascular pathologies in all HHT models, albeit to varying degrees. Transcriptomic profiling further indicated that ANG2 inhibition normalized the brain vasculature by impacting a subset of genes involved in angiogenesis and cell migration processes.

CONCLUSIONS

Elevation of ANG2 in the brain vasculature is a shared trait among the mouse models of the common forms of HHT. Inhibition of ANG2 activity can significantly limit or prevent brain arteriovenous malformation formation and blood vessel enlargement in HHT mice. Thus, ANG2-targeted therapies may represent a compelling approach to treat arteriovenous malformations and vascular pathologies related to all forms of HHT.

Unsupervised machine learning algorithms identify expected haemorrhage relationships but define unexplained coagulation profiles mapping to thrombotic phenotypes in hereditary haemorrhagic telangiectasia

Hereditary haemorrhagic telangiectasia (HHT) can result in challenging anaemia and thrombosis phenotypes. Clinical presentations of HHT vary for relatives with identical casual mutations, suggesting other factors may modify severity. To examine objectively, we developed unsupervised machine learning algorithms to test whether haematological data at presentation could be categorised into sub-groupings and fitted to known biological factors. With ethical approval, we examined 10 complete blood count (CBC) variables, four iron index variables, four coagulation variables and eight iron/coagulation indices combined from 336 genotyped HHT patients (40% male, 60% female, 86.5% not using iron supplementation) at a single centre. T-SNE unsupervised, dimension reduction, machine learning algorithms assigned each high-dimensional datapoint to a location in a two-dimensional plane. k-Means clustering algorithms grouped into profiles, enabling visualisation and inter-profile comparisons of patients' clinical and genetic features. The unsupervised machine learning algorithms using t-SNE and k-Means identified two distinct CBC profiles, two iron profiles, four clotting profiles and three combined profiles. Validating the methodology, profiles for CBC or iron indices fitted expected patterns for haemorrhage. Distinct coagulation profiles displayed no association with age, sex, C-reactive protein, pulmonary arteriovenous malformations (AVMs), ENG/ACVRL1 genotype or epistaxis severity. The most distinct profiles were from t-SNE/k-Means analyses of combined iron-coagulation indices and mapped to three risk states - for venous thromboembolism in HHT; for ischaemic stroke attributed to paradoxical emboli through pulmonary AVMs in HHT; and for cerebral abscess attributed to odontogenic bacteremias in immunocompetent HHT patients with right-to-left shunting through pulmonary AVMs. In conclusion, unsupervised machine learning algorithms categorise HHT haematological indices into distinct, clinically relevant profiles which are independent of age, sex or HHT genotype. Further evaluation may inform prophylaxis and management for HHT patients' haemorrhagic and thrombotic phenotypes.

Comparing Characteristics and Treatment of Brain Vascular Malformations in Children and Adults with HHT

Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant disease characterized by the development of vascular malformations (VMs) in organs such as the brain and lungs, as well as telangiectases on mucosal surfaces. Prophylactic treatment of organ VMs may prevent potential complications, such as hemorrhage. However, brain VM treatment-surgical resection, embolization, and/or radiosurgery-is not recommended for all patients due to the associated risks. Given the scarcity of data regarding HHT-related brain VM presentation and treatment trends in pediatric patients, we aim to describe the clinical presentations and the patterns of treatment of HHT-related brain VMs in a pediatric cohort, and compare pediatric trends to those of adults. Demographic and clinical data were analyzed in 114 pediatric patients with HHT-related brain VMs and compared with a cohort of 253 adult patients enrolled in the multicenter Brain Vascular Malformation Consortium HHT Project. Our data demonstrated that a higher proportion of pediatric patients with HHT-related brain VMs were symptomatic at presentation (p = 0.004). Moreover, a higher proportion of pediatric patients presented with intracranial hemorrhage (p < 0.001) and seizure (p = 0.002) compared to adult patients. Surgical resection was the most common brain VM treatment modality in both children and adults. We conclude that pediatric patients may be more likely to present with symptoms and complications from brain VMs, supporting the case for screening for brain VMs in children with HHT.

Improving Hereditary Hemorrhagic Telangiectasia Molecular Diagnosis: A Referral Center Experience

BACKGROUND

Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular disease inherited in an autosomal dominant manner. Disease-causing variants in endoglin (ENG) and activin A receptor type II-like 1 (ACVRL1) genes are detected in more than 90% of the patients undergoing molecular testing. The identification of variants of unknown significance is often seen as a challenge in clinical practice that makes family screening and genetic counseling difficult. Here, we show that the implementation of cDNA analysis to assess the effect of splice site variants on mRNA splicing is a powerful tool.

METHODS

Gene panel sequencing of genes associated with HHT and other arteriovenous malformation-related syndromes was performed. To evaluate the effect of the splice site variants, cDNA analysis of ENG and ACVRL1 genes was carried out.

RESULTS

three novel splice site variants were identified in ENG (c.68-2A > T and c.1311+4_1311+8del) and ACVLR1 (c.526-6C > G) genes correspondingly in three individuals with HHT that met ≥ 3 Curaçao criteria. All three variants led to an aberrant splicing inducing exon skipping (ENG:c.68-2A > T and ACVRL1:c.526-6C > G) or intron retention (ENG:c.1311+4_1311+8del) allowing the confirmation of the predicted effect on splicing and the reclassification from unknown significance to pathogenic/likely pathogenic of two of them.

CONCLUSIONS

RNA analysis should be performed to assess and/or confirm the impact of variants on splicing. The molecular diagnosis of HHT patients is crucial to allow family screening and accurate genetic counseling. A multidisciplinary approach including clinicians and geneticists is crucial when dealing with patients with rare diseases.

Multidisciplinary coordinated care of hereditary hemorrhagic telangiectasia (Osler-Weber-Rendu disease)

Hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease, is a rare disorder with a case prevalence as high as one in 5000, causing arteriovenous malformations in multiple organ systems. HHT is familial with autosomal dominant inheritance, with genetic testing allowing confirmation of the diagnosis in asymptomatic kindreds. Common clinical manifestations are epistaxis and intestinal lesions causing anemia and requiring transfusions. Pulmonary vascular malformations predispose to ischemic stroke and brain abscess and may cause dyspnea and cardiac failure. Brain vascular malformations can cause hemorrhagic stroke and seizures. Rarely, liver arteriovenous malformations can cause hepatic failure. A form of HHT can cause juvenile polyposis syndrome and colon cancer. Specialists in multiple fields may be called to care for one or more aspects of HHT, but few are familiar with evidence-based guidelines for HHT management or see a sufficient number of patients to gain experience with the unique characteristics of the disease. Primary care physicians and specialists are often unaware of the important manifestations of HHT in multiple systems and the thresholds for their screening and appropriate management. To improve familiarity, experience, and coordinated multisystem care for patients with HHT, the Cure HHT Foundation, which advocates for patients and families with this disease, has accredited 29 centers in North America with designated specialists for the evaluation and care of patients with HHT. Team assembly and current screening and management protocols are described as a model for evidence-based, multidisciplinary care in this disease.

Brain arteriovenous malformation in hereditary hemorrhagic telangiectasia: Recent advances in cellular and molecular mechanisms

Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by vessel dilatation, such as telangiectasia in skin and mucosa and arteriovenous malformations (AVM) in internal organs such as the gastrointestinal tract, lungs, and brain. AVMs are fragile and tortuous vascular anomalies that directly connect arteries and veins, bypassing healthy capillaries. Mutations in transforming growth factor β (TGFβ) signaling pathway components, such as ENG (ENDOGLIN), ACVRL1 (ALK1), and SMAD4 (SMAD4) genes, account for most of HHT cases. 10-20% of HHT patients develop brain AVMs (bAVMs), which can lead to vessel wall rupture and intracranial hemorrhages. Though the main mutations are known, mechanisms leading to AVM formation are unclear, partially due to lack of animal models. Recent mouse models allowed significant advances in our understanding of AVMs. Endothelial-specific deletion of either Acvrl1, Eng or Smad4 is sufficient to induce AVMs, identifying endothelial cells (ECs) as primary targets of BMP signaling to promote vascular integrity. Loss of ALK1/ENG/SMAD4 signaling is associated with NOTCH signaling defects and abnormal arteriovenous EC differentiation. Moreover, cumulative evidence suggests that AVMs originate from venous ECs with defective flow-migration coupling and excessive proliferation. Mutant ECs show an increase of PI3K/AKT signaling and inhibitors of this signaling pathway rescue AVMs in HHT mouse models, revealing new therapeutic avenues. In this review, we will summarize recent advances and current knowledge of mechanisms controlling the pathogenesis of bAVMs, and discuss unresolved questions.

Liver Transplantation for Extra-Hepatic Manifestation of Hereditary Hemorrhagic Telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is a rare genetic disorder distinguished by multiple arteriovenous malformations that can affect the liver and lungs, and additionally cause high-output heart failure. Effective medical treatment for HHT-related heart failure is limited. While most types of heart failure are contraindications in liver transplants, HHT-related high-output heart failure is an indication for a liver transplant. However, this is rarely performed as it poses a higher-than-average intraoperative risk. We present a case of a 57-year-old female patient with HHT and high-output heart failure from HHT who underwent a successful orthotopic liver transplant to significantly improve her heart function. Incidentally, the patient had a concomitant diagnosis of primary biliary cholangitis (PBC) from her explanted liver. We review the literature on liver transplants related to HHT and perioperative risks associated with heart failure and pulmonary hypertension that may be associated with both HHT and PBC.

Hereditary Hemorrhagic Telangiectasia Associating Neuropsychiatric Manifestations with a Significant Impact on Disease Management-Case Report and Literature Review

(1) Background: Genetic hereditary hemorrhagic telangiectasia (HHT) is clinically diagnosed. The clinical manifestations and lack of curative therapeutic interventions may lead to mental illnesses, mainly from the depression-anxiety spectrum. (2) Methods: We report the case of a 69-year-old patient diagnosed with HHT and associated psychiatric disorders; a comprehensive literature review was performed based on relevant keywords. (3) Results: Curaçao diagnostic criteria based the HHT diagnosis in our patient case at 63 years old around the surgical interventions for a basal cell carcinoma, after multiple episodes of epistaxis beginning in childhood, but with a long symptom-free period between 20 and 45 years of age. The anxiety-depressive disorder associated with nosocomephobia resulted in a delayed diagnosis and low adherence to medical monitoring. A comprehensive literature review revealed the scarcity of publications analyzing the impact of psychiatric disorders linked to this rare condition, frequently associating behavioral disengagement as a coping strategy, psychological distress, anxiety, depression, and hopelessness. (4) Conclusions: As patients with HHT face traumatic experiences from disease-related causes as well as recurring emergency hospital visits, active monitoring for mental illnesses and psychological support should be considered as part of the initial medical approach and throughout the continuum of care.

Whole genome sequences discriminate hereditary hemorrhagic telangiectasia phenotypes by non-HHT deleterious DNA variation

The abnormal vascular structures of hereditary hemorrhagic telangiectasia (HHT) often cause severe anemia due to recurrent hemorrhage, but HHT causal genes do not predict the severity of hematological complications. We tested for chance inheritance and clinical associations of rare deleterious variants in which loss-of-function causes bleeding or hemolytic disorders in the general population. In double-blinded analyses, all 104 patients with HHT from a single reference center recruited to the 100 000 Genomes Project were categorized on new MALO (more/as-expected/less/opposite) sub-phenotype severity scales, and whole genome sequencing data were tested for high impact variants in 75 HHT-independent genes encoding coagulation factors, or platelet, hemoglobin, erythrocyte enzyme, and erythrocyte membrane constituents. Rare variants (all gnomAD allele frequencies <0.003) were identified in 56 (75%) of these 75 HHT-unrelated genes. Deleteriousness assignments by Combined Annotation Dependent Depletion (CADD) scores >15 were supported by gene-level mutation significance cutoff scores. CADD >15 variants were identified in 38/104 (36.5%) patients with HHT, found for 1 in 10 patients within platelet genes; 1 in 8 within coagulation genes; and 1 in 4 within erythrocyte hemolytic genes. In blinded analyses, patients with greater hemorrhagic severity that had been attributed solely to HHT vessels had more CADD-deleterious variants in platelet (Spearman ρ = 0.25; P = .008) and coagulation (Spearman ρ = 0.21; P = .024) genes. However, the HHT cohort had 60% fewer deleterious variants in platelet and coagulation genes than expected (Mann-Whitney test P = .021). In conclusion, patients with HHT commonly have rare variants in genes of relevance to their phenotype, offering new therapeutic targets and opportunities for informed, personalized medicine strategies.

An in vitro study on the effect of bevacizumab on endothelial cell proliferation and VEGF concentration level in patients with hereditary hemorrhagic telangiectasia

Previous studies have demonstrated that vascular endothelial growth factor (VEGF) is upregulated in patients with hereditary hemorrhagic telangiectasia (HHT). The use of Bevacizumab as an anti-angiogenic treatment agent seems promising. The purpose of the present in vitro study was to determine the efficacy and potential toxicity levels of bevacizumab on cell proliferation and VEGF concentrations in endothelial cells of HHT patients. In this in vitro study, endothelial cells from patients with HHT and HUVECs (control) were incubated with different concentration levels of bevacizumab (2, 4, 6, 8 or 10 mg/ml). After 24, 48 or 72 h, the cell proliferation was assessed by Alamar Blue^® Assay and the VEGF levels in the cell culture supernatants were measured by VEGF-ELISA. All endothelial cells incubated with bevacizumab showed an initial decrease in cell proliferation. Cell proliferation recovered within 72 h in cell cultures incubated with concentration levels of up to 4 mg/ml bevacizumab, whereas those incubated with higher concentration levels showed a continuous decline in cell proliferation. VEGF expression decreased after 24 h in cell cultures incubated with bevacizumab concentration levels of 2 and 4 mg/ml but increased again after 48 h. Cell cultures incubated with bevacizumab concentration levels of 10 mg/ml showed a constant decline in VEGF expression without any tendency for recovery. Translating these results into daily clinical practice, the present study suggests that the intranasal submucosal injection of bevacizumab in HHT patients should not exceed a concentration level of 4 mg/ml. Overall, higher bevacizumab concentration levels not only reduce VEGF expression but pose a higher risk of toxic effects on endothelial cells as they jeopardize cell proliferation.

Hereditary hemorrhagic telangiectasia: First demonstration of a founder effect in Italy; the ACVRL1 c.289_294del variant originated in the country of Bergamo 200 years ago

Background

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder, affecting 1:5000 individuals worldwide. All the genes associated to the disease (ENG, ACVRL1, SMAD4, GDF2) belong to the TGF‐β/BMPs signaling pathway.

We found 19 HHT unrelated families, coming from a Northern Italy region and sharing the ACVRL1 in‐frame deletion c.289_294del (p.H97_N98).

Methods

To test the hypothesis of a founder effect, we analyzed 88 subjects from 19 families (66 variant carriers, showing clinical signs of HHT, and 22 non‐carriers, unaffected) using eight microsatellite markers within 3.7 Mb around the ACVRL1 locus. After the haplotype reconstruction, age estimation of the variant was carried out.

Results

We observed a common disease haplotype in 16/19 families, while three families showed evidence of recombination around the ACVRL1 locus. The subsequent age estimation analyses suggested that the mutation occurred about 8 generations ago, corresponding to about 200 years ago. We also present novel in silico and modeling data supporting the variant pathogenicity: the deletion alters the protein stability and removes the unique extracellular glycosylation site.

Conclusion

We have demonstrated, for the first time, a “founder effect” for a HHT pathogenic variant in Italy.

Sclerotherapy for Hereditary Hemorrhagic Telangiectasia-Related Epistaxis: A Systematic Review

OBJECTIVES

Hereditary hemorrhagic telangiectasia (HHT) is a common inherited condition characterized by mucosal telangiectasias, recurrent epistaxis, and arteriovenous malformations. HHT results in detriment to quality of life. Morbidity and mortality result from severe anemia. Conventional interventions for HHT-related epistaxis include nasal packing, diathermy, lasers, coblation, microdebridement, bevacizumab (topical and systemic), as well as septodermoplasty and nasal closure. Sclerotherapy has been recently described in the literature as a novel approach to HHT-related epistaxis. We hypothesize that sclerotherapy is an effective treatment for HHT-related epistaxis and improves upon the current standard of care for this disease.

METHODS

A systematic review was conducted to study sclerotherapy for treating HHT-related epistaxis. Ovid MEDLINE, Ovid EMBASE, Scopus, and Web of Science were searched. Articles were evaluated and excluded according to PRISMA guidelines and reviewed by 2 authors. Reported variables included number of injections, months of follow up, changes in Epistaxis Severity Score, previous treatments used to control epistaxis, and post-injection side effects.

RESULTS

Seven studies with a total of 196 patients met inclusion criteria. Three studies reported significant improvement as measured by the Epistaxis Severity Score scale. One reported improvement through subjective patient surveys and others used the Bergler-Sadick scale to measure frequency and intensity of epistaxis. All studies reported improvement in HHT-related epistaxis. The lack of uniform reporting measures however precluded formal meta-analysis.

CONCLUSIONS

Based on limited data, sclerotherapy appears to be effective for treating HHT-related epistaxis and offers promise for treating this recalcitrant condition. However, larger, prospective, multi-centered studies using universally validated instruments for epistaxis are needed to definitively evaluate outcomes from sclerotherapy.

A retrospective cohort study on European Reference Network for Rare Vascular Diseases 5 outcome measures for Hereditary Haemorrhagic Telangiectasia in Denmark

Background

Hereditary Haemorrhagic Telangiectasia (HHT) is an autosomal dominant disorder characterized by several clinical symptoms including epistaxis, arteriovenous malformations (AVM), and telangiectasia. In 2018, European Reference Network for Rare Vascular Diseases (VASCERN) recommended five outcome measures for HHT-patients to guide health care providers, some with limited experience in treating HHT, and thereby maximizing the number of HHT-patients receiving good care. The outcome measures cover the following aspects: (1) 90% of the patients should receive a pulmonary AVM (PAVM) screening; (2) 90% of the patients should receive written advice on nosebleed; (3) 70% should be assessed for iron deficiency; (4) 100% of the patients should receive written advice on antibiotic (AB) prophylaxis prior to dental and surgical procedures, and (5) 100% of relevant patients should receive written advice on pregnancy. We have introduced the outcome measures as Benchmarks in our HHT-centre and wanted to evaluate the extend of implementation we have achieved. We constantly struggle to secure the best possible treatment of our HHT-patients.

Methods

The study was a non-interventional retrospective study. Data was collected manually from patient records and from the Danish HHT-database.

Results

A total of 180 HHT-patients were included, all diagnosed in the period from January 1st, 2016, to December 31st, 2020. All patients were screened for PAVM. We could confirm that 66% of patients who had epistaxis received thoroughly advice. Assessment for iron deficiency was performed in 80% of the adult patients. Thoroughly advice on AB prophylaxis was documented in 75%. Thoroughly advice on pregnancy was documented in 80% of female patients 15–45 years of age. There were no significant differences over time for any of the outcome measures.

Conclusions

The Danish HHT-centre reached the target threshold for outcome measures 1 and 3. It could not be documented that the target thresholds for outcome measures 2, 4, and 5 were achieved. As information and education are a very important part of HHT care, focus on and documentation that all patients receive the relevant advice must be a priority in order to ensure best care.

The European Rare Disease Network for HHT Frameworks for management of hereditary haemorrhagic telangiectasia in general and speciality care

Hereditary haemorrhagic telangiectasia (HHT) is a complex, multisystemic vascular dysplasia affecting approximately 85,000 European Citizens. In 2016, eight founding centres operating within 6 countries, set up a working group dedicated to HHT within what became the European Reference Network on Rare Multisystemic Vascular Diseases. By launch, combined experience exceeded 10,000 HHT patients, and Chairs representing 7 separate specialties provided a median of 24 years' experience in HHT. Integrated were expert patients who focused discussions on the patient experience. Following a 2016-2017 survey to capture priorities, and underpinned by more than 40 monthly meetings, and new data acquisitions, VASCERN HHT generated position statements that distinguish expert HHT care from non-expert HHT practice. Leadership was by specialists in the relevant sub-discipline(s), and 100% consensus was required amongst all clinicians before statements were published or disseminated. One major set of outputs targeted all healthcare professionals and their HHT patients, and include the new Orphanet definition; Do's and Don'ts for common situations; Outcome Measures suitable for all consultations; COVID-19; and anticoagulation. The second output set span aspects of vascular pathophysiology where greater understanding will assist organ-specific specialist clinicians to provide more informed care to HHT patients. These cover cerebral vascular malformations and screening; mucocutaneous telangiectasia and differential diagnosis; anti-angiogenic therapies; circulatory interplays between anaemia and arteriovenous malformations; and microbiological strategies to counteract loss of normal pulmonary capillary function. Overall, the integrated outputs, and documented current practices, provide frameworks for approaches that augment the health and safety of HHT patients in diverse health-care settings.

Hereditary hemorrhagic telangiectasia (HHT): a practical guide to management

Hereditary hemorrhagic telangiectasia (HHT), the second most common inherited bleeding disorder, is associated with the development of malformed blood vessels. Abnormal blood vessels may be small and cutaneous or mucosal (telangiectasia), with frequent complications of bleeding, or large and visceral (arteriovenous malformations [AVMs]), with additional risks that can lead to significant morbidity and even mortality. HHT can present in many different ways and can be difficult to recognize, particularly in younger patients in the absence of a known family history of disease or epistaxis, its most common manifestation. HHT is commonly diagnosed using the established Curaçao clinical criteria, which include (1) family history, (2) recurrent epistaxis, (3) telangiectasia, and (4) visceral AVMs. Fulfillment of 3 or more criteria provides a definite diagnosis of HHT, whereas 2 criteria constitute a possible diagnosis of HHT. However, these criteria are insufficient in children to rule out disease due to the age-dependent development of some of these criteria. Genetic testing, when positive, can provide definitive diagnosis of HHT in all age groups. Clinical course is often complicated by significant epistaxis and/or gastrointestinal bleeding, leading to anemia in half of adult patients with HHT. The management paradigm has recently shifted from surgical approaches to medical treatments aimed at control of chronic bleeding, such as antifibrinolytic and antiangiogenic agents, combined with aggressive iron replacement with intravenous iron. Guidelines for management of HHT, including screening and treatment, were determined by expert consensus and originally published in 2009 with updates and new guidelines in 2020.

Connective Tissue Disorders and Cardiovascular Complications: The Indomitable Role of Transforming Growth Factor-β Signaling

Marfan Syndrome (MFS) and Loeys-Dietz Syndrome (LDS) represent heritable connective tissue disorders that segregate with a similar pattern of cardiovascular defects (thoracic aortic aneurysm, mitral valve prolapse/regurgitation, and aortic dilatation with regurgitation). This pattern of cardiovascular defects appears to be expressed along a spectrum of severity in many heritable connective tissue disorders and raises suspicion of a relationship between the normal development of connective tissues and the cardiovascular system. With overwhelming evidence of the involvement of aberrant Transforming Growth Factor-beta (TGF-β) signaling in MFS and LDS, this signaling pathway may represent the common link in the relationship between connective tissue disorders and their associated cardiovascular complications. To further explore this hypothetical link, this chapter will review the TGF-β signaling pathway, the heritable connective tissue syndromes related to aberrant TGF-β signaling, and will discuss the pathogenic contribution of TGF-β to these syndromes with a primary focus on the cardiovascular system.

Hepatic Transplantation Raises Concern for Vascular Infrastructure Compromise: A Case Study of Debilitating Arteriovenous Malformation

The post-operative realm for hepatic transplant patients presents many challenges, but of them all, we take a deeper dive into an increased risk of associated cerebrovascular events. Cerebrovascular diseases, such as cerebral arteriovenous malformation (AVM), are a leading cause of death following a liver transplant. We present a unique case of a liver transplant patient who presented with no brainstem reflexes three months into the post-transplant period. Imaging studies revealed a ruptured AVM within the foramen magnum and cervicomedullary junction, as well as substantial cerebral hemorrhage. While establishing the exact cause of the AVM is not as trivial as it may appear, side effects associated with post-transplantation management regimens and possible congenital factors do shed some light on notable considerations. Given the potential damage associated with ruptured AVMs, poor patient outcomes are unfortunately not as rare as one would hope. This case highlights a rare but highly possible occurrence for cerebrovascular complications, specifically AVM rupture linked to liver transplantation and the systemic changes associated with a procedure as invasive as liver transplantation.

Pathogenesis and therapy of arteriovenous malformations: A case report and narrative review

Arteriovenous malformations (AVMs) are abnormal communications between arteries and veins that lack intervening capillary beds. They have been described in almost every organ in the body, emerging sporadically or as part of well-described syndromes. Hereditary hemorrhagic telangiectasia (HHT) is a rare, progressive, and lifelong disease characterized by AVMs and recurrent hemorrhaging. In the last 2 decades, significant advances have been made in understanding the pathogenesis of this condition. The accumulation of knowledge has led to a natural evolution of therapy, from open surgery to endovascular procedures, and now to a role for medications in certain AVMs. Here, we review a case of HHT and describe the most up-to-date clinical practice, including diagnosis of HHT, subtypes of HHT, and medical therapy.

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.

SARS-CoV-2 Infection in Hereditary Hemorrhagic Telangiectasia Patients Suggests Less Clinical Impact Than in the General Population

At the moment of writing this communication, the health crisis derived from the COVID-19 pandemic has affected more than 120 million cases, with 40 million corresponding to Europe. In total, the number of deaths is almost 3 million, but continuously rising. Although COVID-19 is primarily a respiratory disease, SARS-CoV-2 infects also endothelial cells in the pulmonary capillaries. This affects the integrity of the endothelium and increases vascular permeability. In addition, there are serious indirect consequences, like disruption of endothelial cells’ junctions leading to micro-bleeds and uncontrolled blood clotting. The impact of COVID-19 in people with rare chronic cardiovascular diseases is unknown so far, and interesting to assess, because the virus may cause additional complications in these patients. The aim of the present work was to study the COVID-19 infection among the patients with Hereditary Hemorrhagic Telangiectasia (HHT). A retrospective study was carried out in a 138 HHT patients’ sample attending an Ear Nose and Throat (ENT) reference consult. The evaluation of the COVID-19 infection in them reveals milder symptoms; among the 25 HHT patients who were infected, only 3 cases were hospitalized, and none of them required ICU or ventilation assistance. The results are discussed in the light of macrophage immune response.

Classification of endonasal HHT lesions using digital microscopy

BACKGROUND

Recurrent spontaneous epistaxis is the most common clinical manifestation and the most debilitating symptom in hereditary haemorrhagic telangiectasia (HHT) patients. To this date, there exist only a classification of HHT patients by different genetic mutations. There is no standard classification for the mucocutaneous endonasal manifestations of HHT. The aim of the present study was to document the variety of endonasal HHT lesions using digital microscopy and to propose a clinical classification.

METHODS

We recorded the endonasal HHT lesions of 28 patients using a digital microscope. We reconstructed the 3D images und videos recorded by digital microscope afterwards and classified the endonasal lesions of HHT in two classes: Grade A, presence of only flat telangiectasias in the mucosa level and Grade B, (additional) presence of raised berry or wart-like telangiectasia spots. We investigated also Haemoglobin level by routine laboratory procedures, plasma VEGF level by ELISA, Severity of epistaxis by epistaxis severity score (ESS) and quality of life by a linear visual analogue scale (VAS).

RESULTS

We found a higher quality of life and a lower severity of epistaxis in Grade A patients in comparison to Grade B patients. No difference in plasma VEGF level and in Haemoglobin between Grad A patients and Grade B patients could be detected. Plasma VEGF levels showed no gender specific differences. It could also not be correlated to the extranasal manifestation.

CONCLUSION

The classification for endonasal manifestation of HHT proposed in this study indicates severity of epistaxis und quality of life. Digital microscopy with the ability of 3D reconstruction of images presents a useful tool for such classifications. The classification of endonasal HHT lesions using digital microscopy allows to evaluate the dynamic of HHT lesions in the course of time independent of examiner. This allows also to evaluate the efficacy of the different treatment modalities by dynamic of HHT lesions. Moreover digital microscopy is very beneficial in academic teaching of rare diseases.

Founder Effects in Hereditary Hemorrhagic Telangiectasia

A founder effect can result from the establishment of a new population by individuals from a larger population or bottleneck events. Certain alleles may be found at much higher frequencies because of genetic drift immediately after the founder event. We provide a systematic literature review of the sporadically reported founder effects in hereditary hemorrhagic telangiectasia (HHT). All publications from the ACVRL1, ENG and SMAD4 Mutation Databases and publications searched for terms “hereditary hemorrhagic telangiectasia” and “founder” in PubMed and Scopus, respectively, were extracted. Following duplicate removal, 141 publications were searched for the terms “founder” and “founding” and the etymon “ancest”. Finally, 67 publications between 1992 and 2020 were reviewed. Founder effects were graded upon shared area of ancestry/residence, shared core haplotypes, genealogy and prevalence. Twenty-six ACVRL1 and 12 ENG variants with a potential founder effect were identified. The bigger the cluster of families with a founder mutation, the more remarkable is its influence to the populational ACVRL1/ENG ratio, affecting HHT phenotype. Being aware of founder effects might simplify the diagnosis of HHT by establishing local genetic algorithms. Families sharing a common core haplotype might serve as a basis to study potential second-hits in the etiology of HHT.

A comparative study of two grading systems for epistaxis in hereditary haemorrhagic telangiectasia

BACKGROUND

Different institutions use different grading systems for hereditary haemorrhagic telangiectasia (HHT)-associated epistaxis. It is important to have a universal, standardized grading system to compare and evaluate the effectiveness of different treatment options. We introduced the "Intensity, Frequency and need for Blood Transfusion" (IFT) grading system for HHT-associated epistaxis in 2008. Hoag et al. proposed the "Epistaxis Severity Score" (ESS) for the International HHT foundation in 2010. This study aimed to evaluate the potential correlation between the ESS and IFT grading systems.

METHODS

The study included 354 simultaneous reports using the IFT and ESS from 106 patients. The correlation between the ESS, IFT and haemoglobin levels was measured using Pearson's correlation coefficient. The ESS and IFT were scored simultaneously by the patient and doctor in 48 cases to evaluate if there was a discrepancy in the scoring applied by either set of responders.

RESULTS

The measured correlation between the two grading systems was good (0.75). The grade of epistaxis reported by patients and doctors respectively showed no significant difference. Both the IFT and ESS grading systems correlate significantly to the haemoglobin level.

CONCLUSIONS

Both the IFT and ESS scores correlate to each other, and their results are comparable. Whether the IFT or ESS scoring was performed by the patient or doctor had no significant impact.

Mutational and phenotypic characterization of hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular dysplasia. Care delivery for HHT patients is impeded by the need for laborious, repeated phenotyping and gaps in knowledge regarding the relationships between causal DNA variants in ENG, ACVRL1, SMAD4 and GDF2, and clinical manifestations. To address this, we analyzed DNA samples from 183 previously uncharacterized, unrelated HHT and suspected HHT cases using the ThromboGenomics high-throughput sequencing platform. We identified 127 rare variants across 168 heterozygous genotypes. Applying modified American College of Medical Genetics and Genomics Guidelines, 106 variants were classified as pathogenic/likely pathogenic and 21 as nonpathogenic (variant of uncertain significance/benign). Unlike the protein products of ACVRL1 and SMAD4, the extracellular ENG amino acids are not strongly conserved. Our inferences of the functional consequences of causal variants in ENG were therefore informed by the crystal structure of endoglin. We then compared the accuracy of predictions of the causal gene blinded to the genetic data using 2 approaches: subjective clinical predictions and statistical predictions based on 8 Human Phenotype Ontology terms. Both approaches had some predictive power, but they were insufficiently accurate to be used clinically, without genetic testing. The distributions of red cell indices differed by causal gene but not sufficiently for clinical use in isolation from genetic data. We conclude that parallel sequencing of the 4 known HHT genes, multidisciplinary team review of variant calls in the context of detailed clinical information, and statistical and structural modeling improve the prognostication and treatment of HHT.

[Hereditary hemorrhagic telangiectasia: symptoms and diagnostic latency]

OBJECTIVE

Patients with hereditary hemorrhagic Telangiectasia (HHT) suffer from a rare and systemic disease which is characterized by vascular malformations leading to a variety of different symptoms.

MATERIAL AND METHODS

A retrospective review of patients who were referred to our new HHT Center of Excellence (HHT COE) for evaluation and treatment between April 2014 and August 2019 was performed.

RESULTS

235 patients were treated at the West German HHT Center. 83 % of these were diagnosed with definite HHT (235/282, 83 %) and 9 % with possible HHT (26/282). The average latency between first manifestation and definite diagnosis of HHT was 18 years. Several initial symptoms were direct or indirect signs of bleeding (224/241, 93 %). In 83 % of the patients HHT was reported having caused their degree of disability. Older, female patients and those with severe epistaxis suffered from chronic iron deficiency anemia, took iron preparations (148/261, 57 %) and received 9 blood transfusions on average (± standard deviation: 41, minimum - maximum: 0-400, number of patients: 218). 10 % of all patients tolerated anticoagulant or antiplatelet agents. 74 % of patients with HHT used nasal creams/sprays/oils (177/238) and reported fewer bleedings compared to patients without nasal care (ESS: T-Test: 3.193; p = 0.003; anemia: Chi-square: 5.173; p = 0.023).

CONCLUSIONS

The diagnostic latency of HHT was almost two decades. Patients with HHT particularly suffered from recurrent epistaxis, which was mostly treated with nasal care and coagulative therapies. Antiplatelet or anticoagulant agents can be used in patients with HHT with caution if indicated.

Long-term efficacy assessment of current treatment options for epistaxis in HHT

Purpose

Hereditary hemorrhagic telangiectasia (HHT) is a vascular disorder that presents with recurrent, intractable epistaxis. The aim of this study was to retrospectively analyze the efficacy of various treatment options for epistaxis in patients with HHT, over a period of 18 years, and to correlate these findings with available evidence in the literature.

Methods

Records of patients with HHT, treated for epistaxis between 2000 and 2018 were analyzed. Treatment procedures carried out and their efficacy were extracted and analyzed.

Results

Forty-three records were evaluated. All patients were given nasal humidifying ointments, 93% required acute treatment with bipolar electrocautery, and 60% underwent atraumatic nasal packing. Recurrent cases were treated medically with tranexamic acid (26%), oestrogen (19%), and bevacizumab (2%). Laser photocoagulation was done in selected cases (40%) and if unsuccessful, septal dermoplasty was performed (2.3%). Endovascular embolization was reserved for life-threatening emergencies (7%).

Conclusion

Epistaxis in HHT is not curable, but can be managed by employing a comprehensive stepwise approach. An algorithm for effective and comprehensive management has been presented.