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.

Safety of direct oral anticoagulants in patients with hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a rare vascular dysplasia resulting in visceral arteriovenous malformations and smaller mucocutaneous telangiectasia. Most patients experience recurrent nosebleeds and become anemic without iron supplementation. However, thousands may require anticoagulation for conditions such as venous thromboembolism and/or atrial fibrillation. Over decades, tolerance data has been published for almost 200 HHT-affected users of warfarin and heparins, but there are no published data for the newer direct oral anticoagulants (DOACs) in HHT. METHODS: To provide such data, a retrospective audit was conducted across the eight HHT centres of the European Reference Network for Rare Multisystemic Vascular Diseases (VASCERN), in Denmark, France, Germany, Italy, the Netherlands and the UK. RESULTS: Although HHT Centres had not specifically recommended the use of DOACs, 32 treatment episodes had been initiated by other clinicians in 28 patients reviewed at the Centres, at median age 65 years (range 30-84). Indications were for atrial fibrillation (16 treatment episodes) and venous thromboembolism (16 episodes). The 32 treatment episodes used Apixaban (n = 15), Rivaroxaban (n = 14), and Dabigatran (n = 3). HHT nosebleeds increased in severity in 24/32 treatment episodes (75%), leading to treatment discontinuation in 11 (34.4%). Treatment discontinuation was required for 4/15 (26.7%) Apixaban episodes and 7/14 (50%) Rivaroxaban episodes. By a 4 point scale of increasing severity, there was a trend for Rivaroxaban to be associated with a greater bleeding risk both including and excluding patients who had used more than one agent (age-adjusted coefficients 0.61 (95% confidence intervals 0.11, 1.20) and 0.74 (95% confidence intervals 0.12, 1.36) respectively. Associations were maintained after adjustment for gender and treatment indication. Extreme hemorrhagic responses, worse than anything experienced previously, with individual nosebleeds lasting hours requiring hospital admissions, blood transfusions and in all cases treatment discontinuation, occurred in 5/14 (35.7%) Rivaroxaban episodes compared to 3/15 (20%) Apixaban episodes and published rates of ~ 5% for warfarin and heparin. CONCLUSIONS: Currently, conventional heparin and warfarin remain first choice anticoagulants in HHT. If newer anticoagulants are considered, although study numbers are small, at this stage Apixaban appears to be associated with lesser bleeding risk than Rivaroxaban.

Population data for 17 Y-chromosome STRs in a sample from Apulia (Southern Italy).

The 17 Y-STR loci included in the AmpFLSTR Yfiler PCR Amplification Kit were analyzed in 98 unrelated healthy males from Apulia (Southern Italy). A total of 97 different haplotypes were identified, of which 96 haplotypes were unique and 1 occurred twice. Allele frequencies for each Y-STR locus in pooled sample and estimated value of gene diversity (GD) were evaluated. The lowest value of GD was observed for DYS392 (0.126) and the highest one (0.936) for DYS385. The HD (haplotype diversity) for the studied Y-STR set showed a value of 0.9994, with an HMP (haplotype match probability) value of 0.0006, while the overall DC was 98.98%. Microvariant alleles were found for the DYS458 and DYS385 markers and sequenced. Furthermore, Φ(st)-based genetic distance computation and pair-wise analysis of molecular variance (AMOVA) test were carried out. When comparing our population with the Apulia sample previously investigated, the AMOVA analysis detected no evidence for significant differentiation. The comparison with all Italian populations submitted to the YHRD website showed no relevant differences with all Southern Italian populations (San Giorgio La Molara, Belvedere, Trapani and Catania) and significant genetic deviation with all Northern Italian populations (Udine, Biella, La Spezia, Modena, Ravenna, Marche and North Sardinia). Moreover, the other populations and meta-populations belonging to the whole Mediterranean area (Croatia, Macedonia, Albania, Greece, Turkey, Israel, Libya, Tunisia, Algeria, Morocco and Spain) were different from our Apulia sample. The data were submitted to YHRD.

Hereditary hemorrhagic telangiectasia: clinical features in ENG and ALK1 mutation carriers.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a genetic disorder characterized by epistaxis, mucocutaneous telangiectases and visceral arteriovenous malformations (AVMs), particularly in the brain (CAVMs), lungs (PAVMs), liver (HAVMs) and gastrointestinal tract (GI). The identification of a mutated ENG (HHT1) or ALK-1 (HHT2) gene now enables a genotype-phenotype correlation. OBJECTIVE: To determine the incidence of visceral localizations and evaluate phenotypic differences between ENG and ALK1 mutation carriers. METHODS: A total of 135 consecutive adult patients were subjected to mutational screening in ENG and ALK1 genes and instrumental tests to detect AVMs, such as chest-abdomen multislice computed tomography (MDCT), brain magnetic resonance imaging and magnetic resonance angiography (MRI/MRA), upper endoscopy, were offered to all patients, independent of presence of clinical symptoms. The 122 patients with identified mutations were enrolled in the study and genotype-phenotype correlations were established. RESULTS: PAVMs and CAVMs were significantly more frequent in HHT1 (75% vs. 44%, P < 0.0005; 20% vs. 0%, P < 0.002, respectively) and HAVMs in HHT2 (60% vs. 84%, P < 0.01). No age difference was found for PAVMs whereas HAVMs were significantly higher in older patients in both HHT1 and HHT2. Neurological manifestations secondary to CAVMs/PAVMs were found only in HHT1 patients, whereas severe liver involvement was detected only in HHT2. Respiratory symptoms were mainly detected in HHT1. CONCLUSIONS: Our study evidences a higher visceral involvement in HHT1 and HHT2 compared with previous reports. HHT1 is more frequently associated with congenital AVM malformations, such as CAVMs and PAVMs whereas HHT2 predominantly involves the liver. The ENG gene should be first targeted for mutational screening in the presence of large PAVM in patients < 45 years.

Hereditary haemorrhagic telangiectasia: a rare disease as a model for the study of human atherosclerosis.

Hereditary Haemorrhagic Telangiectasia (HHT) or Rendu-Osler-Weber syndrome is an autosomal dominant disease characterized by local angiodysplasia affecting different organism districts. From a clinical viewpoint, HHT patients suffer from epistaxis, mucocutaneous telangiectases and arteriovenous malformations in various organs. Mutations in two known genes (ENG and ALK1) account for the majority of HHT patients. Additional loci are predicted, but the underlying genes are still to be identified. Moreover, SMAD4 mutations have been reported to cause JP-HHT combined syndrome. Both endoglin and ALK-1 bind to various growth factors in the context of the Transforming Growth Factors (TGF)-beta superfamily and their expression is restricted to vascular endothelial cells and very few other cell types, such as activated monocytes. Endoglin and ALK1 mutations are thought to affect endothelial cell metabolism, angiogenesis and vascular remodelling, even if the precise mechanism leading to the HHT lesions is still obscure. Endoglin is also overexpressed in smooth muscle cells of atherosclerotic plaques, suggesting a role for this protein in atherogenesis and plaque progression, as well as in other cardiovascular diseases. Recently, we demonstrated that HHT adult patients display several deficits of both innate and adaptive immune system. Here, we investigated the function of immune cells in HHT pediatric patients. Our results clearly show that HHT children have a normal functionally immune system, and suggest that HHT patients become immunocompromised host during their lifetime, likely due to a precocious immunosenescence. Moreover, the relationship between immune responsiveness in HHT and atherosclerosis are discussed.

Screening for children from families with Rendu-Osler-Weber disease: from geneticist to clinician.

BACKGROUND: Rendu-Osler-Weber syndrome, or hereditary hemorrhagic telangiectasia (HHT), is an autosomal dominant vascular disorder. The syndrome is characterized by telangiectases and arteriovenous malformations (AVMs) affecting skin, mucosae and internal organs. AVMs often remain clinically silent until provoking sudden serious complications, responsible for important morbidity and mortality which can occur both in adulthood and in children. The incidence of AVMs in HHT pediatric populations is unknown. OBJECTIVE: To describe the screening protocol performed in the first genotypically confirmed HHT pediatric population and to estimate the incidence of occult brain, lung and liver AVMs and the different disease phenotypes. MATERIALS AND METHODS: Molecular analysis was performed on 35 children, both symptomatic and asymptomatic, who were family members of probands with a previously identified mutation. Clinical-instrumental examination was performed on the mutation positive cases. Nasal telangiectases were investigated by anterior rhinoscopy. Contrast echocardiography and high resolution thoracic multislice computed tomography (CT) were performed to detect pulmonary arteriovenous malformations (PAVMs), and echo-color Doppler, and abdominal CT to detect hepatic arteriovenous malformations (HAVMs). Brain magnetic resonance imaging was utilized to detect cerebral angiopathic involvement. RESULTS: Molecular analysis demonstrated the mutation-carrier status in 22/35 children. Nineteen children, 12 of whom had epistaxis, positive to molecular testing underwent clinical evaluation. Nasal teleangiectases were found in 68%, mucocutaneous telangiectases (fingers, lips and oral cavity) in 79%, PAVMs in 53%, HAVMs in 47% and cerebral anteriovenous malformations and/or cerebral ischemic changes secondary to PAVMs in 12%. CONCLUSIONS: We evidenced a high incidence of HHT children with occult visceral lesions suggesting that a diagnostic screening may be indicated to appropriately treat brain and lung malformations.

Hereditary Haemorrhagic Telangiectasia (HHT): genetic and molecular aspects.

Hereditary Haemorrhagic Telangiectasia, or Rendu-Osler-Weber syndrome, is a rare autosomal dominant disorder involving the vascular system and is characterised by a highly variable expressivity and age-dependent penetrance. Diagnosis is based on the presence of at least three of four of the following symptoms: spontaneous epistaxis, cutaneous telangiectases, arteriovenous malformations in internal organs and familiarity. Recurrent complications are severe anaemia, stroke, portal and pulmonary hypertension. The peculiar characteristic of this disease is the diffusion of arteriovenous malformations, that is, localised abnormal arteriovenous connections affecting both microvasculature and large vessels. HHT is actually a heterogenous genetic disorder, divided into two clinically indistinguishable forms: HHT1 caused by mutations in endoglin gene mapping on chromosome 9q, and HHT2 caused by mutations in ALK1 located on chromosome 12q. Haploinsufficiency is the underlying mechanism for endoglin and most ALK1 mutations. Such mutations lead to a deficiency in angiogenesis, i.e. the sprouting of new vessels from pre-existing ones. To date, little is still known about the mechanism(s) responsible for lesion formation, development and slow growth. Current models focus on the role that TGF-beta superfamily members, a vast group of multifunctional cytokines, play in endothelial responses to angiogenic stimuli. As both genes seem to act in TGF-beta signal transduction pathways, SMAD proteins are also thought to be involved. There is no clear explanation accounting for the strong variability shown even among members of the same family despite the sharing of the same disease-causing mutation, and why lesions are spatially discrete.

Capillaroscopy of the dorsal skin of the hands in hereditary hemorrhagic telangiectasia.

BACKGROUND: Cutaneous telangiectases are manifestations of hereditary hemorrhagic telangiectasia (HHT), a dominantly inherited disorder. Telangiectases have been studied by skin biopsy, and recently by nailfold capillaroscopy. AIM: To confirm the diagnostic role of nailfold capillaroscopy, and assess the value of skin capillaroscopy of the dorsum of the hands in HHT. DESIGN: Prospective clinical investigation. METHODS: Using a Wild Heerbrugg-M650 microscope, we studied the nailfolds and dorsum of the hands of 88 patients (37 females, 51 males, mean age 39.7 +/- 18.4 years), including 85 with positive genetic testing and three with clinical diagnosis (at least three clinical criteria but a negative genetic test) and 27 controls (13 females, 14 males, mean age 38.6 +/- 19.6 years). RESULTS: Microscopic telangiectases were observed on the dorsum of the hands in 80/88 patients (91%): 77 with positive and three with negative genetic tests. No control showed vascular abnormalities. In six patients (7%), nailfold capillaroscopy showed pseudo-megacapillaries and megacapillaries; the remaining 82 (93%) and all controls, had normal capillaroscopic patterns. DISCUSSION: HHT can induce morphological changes in microcirculation that are more easily detectable on the dorsum of the hands than in the nailfold. Microscopic lesions without macroscopic telangiectases were also noted, suggesting the need for further research. Capillaroscopy may provide an additional non-invasive diagnostic criterion for HHT.

Endoglin gene mutations and polymorphisms in Italian patients with hereditary haemorrhagic telangiectasia.

Autosomal-dominant hereditary haemorrhagic telangiectasia (HHT) is a genetically heterogeneous disease caused by mutations in at least two different loci. We screened for mutations in four Italian families where segregation studies showed clear evidence of linkage to the endoglin (ENG) locus. In addition, one sporadic case and three patients with pulmonary arteriovenous malformations, belonging to small nuclear families unsuitable for linkage analysis, were included in the screening. The proband from each family was investigated using single-strand conformation polymorphism and heteroduplex analysis; potential variants were sequenced. Four novel and one previously reported mutation were detected, as well as three new polymorphisms. The novel mutations included deletions in exon 1 (patient 581/02), exon 5 (patient 780/01) and exon 7 (patient 700/01), and a C-->T229 substitution in exon 3 (patient 462/02). When analysing patient 700/01 and his affected daughter, we encountered a mutant ENG allele with two mutations--a deletion in exon 7 and a substitution in exon 12--which converts isoleucine 575 into threonine, in a non-conserved region. Both mutations were absent in the two healthy sons of the patient, while the polymorphic variant in exon 12 was present in his healthy father. These results and haplotype-segregation studies suggest that a de novo deletion had occurred in the gamete of paternal origin. For the first time the parental germline in which a de novo HHT mutation occurred has been identified.