Hereditary Hemorrhagic Telangiectasia Research Articles

Spontaneous Ischemic Cholecystitis in a Patient with Hereditary Hemorrhagic Telangiectasia (HHT)

Background/Objectives: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by abnormal blood vessel formation, leading to recurrent epistaxis, cutaneous and mucosal telangiectases, and visceral arteriovenous malformations (AVMs). Hepatic involvement may result in complications such as high-output heart failure, portal hypertension, and biliary ischemia. We report an uncommon case of ischemic cholecystitis in a patient with HHT. Methods: A 57-year-old male with HHT type 1, including gastric telangiectases and hepatic AVMs, presented with anemia, melena, epigastric pain, and a history of recurrent epistaxis. Imaging revealed gastric telangiectases and liver AVMs, consistent with HHT. Following an episode of severe epistaxis and aspiration pneumonia, the patient developed right upper quadrant pain. Results: Abdominal CT and ultrasound identified thickening of the gallbladder wall, segmental enhancement defects, and a perivesicular fluid effusion, suggestive of acalculous cholecystitis. A laparoscopic cholecystectomy was performed, revealing ischemic cholecystitis with necrotic gallbladder walls. Conclusions: This case underscores the potential for ischemic cholecystitis in patients with HHT and liver involvement, particularly under conditions of acute hemodynamic instability. Clinicians should be vigilant in recognizing this rare complication, especially in patients with established HHT and associated hepatic vascular anomalies.

Middle meningeal artery embolization and tranexamic acid therapy for subdural hematoma in a patient with hereditary hemorrhagic telangiectasia: illustrative case.

Subdural hematoma is a rare manifestation of hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu disease. Here, the authors present a patient with HHT and a large chronic subdural hematoma, for whom nonsurgical management was pursued. A 49-year-old right-handed male with a history of hypertension and familial HHT presented with complaints of mild confusion and left hemiparesis over several days. Noncontrast head computed tomography images demonstrated a large chronic right hemisphere subdural hematoma compressing the right cerebral hemisphere and causing a 1.3-cm midline shift. Due to concerns about surgical complications arising from hemorrhages of cryptic telangiectasias, the patient was treated conservatively with middle meningeal artery embolization and adjuvant tranexamic acid. There was clinical and radiological resolution several months later. This case highlights the rarity of a subdural hematoma as a manifestation of HHT and the nonsurgical treatment strategy as a mechanism to avoid hemorrhagic complications of surgical evacuation. https://thejns.org/doi/10.3171/CASE24483.

CDK6-mediated endothelial cell cycle acceleration drives arteriovenous malformations in hereditary hemorrhagic telangiectasia.

Increased endothelial cell proliferation is a hallmark of arteriovenous malformations (AVMs) in hereditary hemorrhagic telangiectasia (HHT). Here, we report a cyclin-dependent kinase 6 (CDK6)-driven mechanism of cell cycle deregulation involved in endothelial cell proliferation and HHT pathology. Specifically, endothelial cells from the livers of HHT mice bypassed the G1/S checkpoint and progressed through the cell cycle at an accelerated pace. Phosphorylated retinoblastoma (pRB1)-a marker of G1/S transition through the restriction point-accumulated in endothelial cells from retinal AVMs of HHT mice and endothelial cells from skin telangiectasia samples from HHT patients. Mechanistically, inhibition of activin receptor-like kinase 1 signaling increased key restriction point mediators, and treatment with the CDK4/6 inhibitors palbociclib or ribociclib blocked increases in pRB1 and retinal AVMs in HHT mice. Palbociclib also improved vascular pathology in the brain and liver, and slowed cell cycle progression in endothelial cells and endothelial cell proliferation. Endothelial cell-specific deletion of CDK6 was sufficient to protect HHT mice from AVM pathology. Thus, clinically approved CDK4/6 inhibitors might have the potential to be repurposed for HHT.

Pulmonary arteriovenous malformation in children.

Pulmonary arteriovenous malformations (PAVMs) are rare abnormalities observed mainly in children with hereditary haemorrhagic telangiectasia (HHT). A majority of patients are asymptomatic at the time of detection. However, complications such as hypoxemia, stroke, cerebral abscess and massive hemoptysis can arise if larger PAVMs remain untreated. Larger PAVMs are usually managed successfully with embolization, although reperfusion of PAVMs have been reported post procedure. Early screening for PAVMs is recommended in asymptomatic children with HHT or those at risk for HHT. Longer term surveillance is also essential, to enable timely identification and management of PAVMs.

Is there still a role for nasal closure in hereditary haemorrhagic telangiectasia?

Is there still a role for nasal closure in hereditary haemorrhagic telangiectasia?

Arterial-Lymphatic-Like Endothelial Cells Appear in Hereditary Hemorrhagic Telangiectasia 2 and Contribute to Vascular Leakage and Arteriovenous Malformations.

Arteriovenous malformations (AVMs) are characteristic of hereditary hemorrhagic telangiectasia. Loss-of-function mutations in the activin receptor-like kinase 1 (Alk1) are linked to hemorrhagic telangiectasia type 2. Endothelial-specific deletion of Alk1, endothelial lineage tracing, transcriptomics of single-cell analysis, and electron microscopy were performed to examine the vascular phenotype and characteristics of ALK1-deficient endothelial cells (ECs) after EC-specific Alk1 deletion. Ischemia assays were used to examine the cell capacity for vascular malformation. Connectivity Map with transcriptomic analysis was applied to identify chemical compounds. Specific methods for arteriovenous malformations, such as micro-computed tomography, with other molecular and cell biological tools were also performed. We performed endothelial-specific deletion of Alk1 in mice and found severe arteriovenous malformations and vascular leakage. The transcriptomics of single-cell analysis revealed a new distinctive cell cluster formed after Alk1 deletion where the cells coexpressed arterial and lymphatic endothelial markers. The analysis projected that these cells potentially originated from arterial ECs after Alk1 deletion. This new population was referred to as arterial-lymphatic-like ECs according to its cellular markers, and its appearance was validated in the pulmonary small arteries after Alk1 deletion. Transplantation of these cells caused vascular malformations. Endothelial lineage tracing confirmed that these new arterial-lymphatic-like ECs were derived from ALK1 depleted ECs, potentially arterial ECs. We discovered that SOX17 (SRY-box transcription factor 17) induction was responsible for the derivation of these arterial-lymphatic-like ECs. We showed that direct binding of MDM2 (mouse double minute 2) was required for Sox17 to execute this activity. Inhibition of MDM2 reduced the arteriovenous malformations in the mouse model. Together, our studies revealed the mechanistic underpinnings of ALK1 signaling in regulating the endothelial phenotype and provided possibilities for new therapeutic strategies in hemorrhagic telangiectasia type 2.

Red blood cell alloimmunization in transfused patients with hereditary hemorrhagic telangiectasia: A single centre retrospective study

BackgroundHereditary hemorrhagic telangiectasia (HHT) is a genetic blood vessel disorder which may lead to chronic bleeding and red blood cell (RBC) transfusions. Data on transfusion requirements and complications in HHT patients are sparse. Study Design and MethodsRetrospective chart review was conducted at St. Michael’s Hospital (SMH) in Toronto, Canada. All adults with a definite clinical diagnosis of HHT AND inpatient hospital visits between January 1, 2011 and December 31, 2020 AND had undergone transfusion compatibility testing at SMH, were identified. Data were abstracted from electronic medical records. Simple descriptive statistics were used to analyze data. Institutional Research Ethics Board approval was obtained. Results63 HHT patients underwent compatibility testing and were subsequently transfused at SMH. Median patient age at data abstraction was 70 years (Interquartile Range [IQR]: 18) and 35 (56 %) were female. RBC alloantibodies were found in 23 transfused patients (36.5 %) and were predominantly directed against Rh and Kell antigens: Anti-E (65 %), Anti-K (39 %) and Anti-c (22 %) were most common. Excluding an outlier who received 611 RBC units during the study period, the mean number of RBC units transfused per HHT patient at SMH was 22.1 units (Standard Deviation: 40.9, IQR: 17). Six (9.5 %) transfused patients experienced at least one transfusion reaction. ConclusionRBC alloimmunization rate was 36.5 % in our cohort of transfused HHT patients; this is much higher than described in the general population and another transfused HHT cohort. The most commonly observed alloantibodies were Rh and Kell, supporting our policy of prophylactic phenotypic matching for these antigens for all transfused patients with HHT.

Molecular basis of interchain disulfide-bond formation in BMP-9 and BMP-10.

BMP-9 and BMP-10 are TGF-β family signaling ligands naturally secreted into blood. They act on endothelial cells and are required for proper development and maintenance of the vasculature. In hereditary hemorrhagic telangiectasia, regulation is disrupted due to mutations in the BMP-9/10 pathway, namely in the type I receptor ALK1 or the co-receptor endoglin. It has been demonstrated that BMP-9/10 heterodimers are the most abundant signaling species in the blood, but it is unclear how they form. Unlike other ligands of the TGF-β family, BMP-9 and -10 are secreted as a mixture of monomers and disulfide-linked dimers. Here, we show that the monomers are secreted in a cysteinylated form that crystallizes as a noncovalent dimer. Despite this, monomers do not self-associate at micromolar or lower concentrations and have reduced signaling potency compared to dimers. We further show using protein crystallography that the interchain disulfide of the BMP-9 homodimer adopts a highly strained syn-periplanar conformation. Hence, geometric strain across the interchain disulfide is responsible for the reduced propensity to dimerize, not the cysteinylation. Additionally, we show that the dimerization propensity of BMP-9 is lower than BMP-10 and these propensities can be reversed by swapping residues near the interchain disulfide that form attractive interactions with the opposing monomer. Finally, we discuss the implications of these observations on BMP-9/10 heterodimer formation.

A case report of acute myocardial infarction with hereditary hemorrhagic telangiectasia

Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by epistaxis, gastrointestinal bleeding, iron deficiency anemia, and arteriovenous malformations (AVMs) affecting the lungs, liver, and brain. Owing to its rarity and diagnostic challenges, early identification is often elusive. Underdiagnosis and prolonged diagnostic delays are prevalent. Here, we present the case of a 63-year-old male who presented with chest pain and was diagnosed with an ST-elevation myocardial infarction (STEMI). Subsequently, he underwent placement of a drug-eluting stent in the right coronary artery (RCA). However, recurrent postoperative epistaxis resulted in severe anemia, prompting further investigation leading to the diagnosis of hereditary hemorrhagic telangiectasia through comprehensive medical history and genetic testing. Future studies are warranted to evaluate reperfusion strategies in HHT patients presenting with myocardial infarction.

Hereditary Hemorrhagic Telangiectasia: Pregnancy and Delivery-Specific Considerations and Outcomes.

Prior studies have evaluated maternal outcomes in patients with hereditary hemorrhagic telangiectasia (HHT), yet pregnancy- and delivery-specific data remain limited. This study aims to evaluate pregnancy and delivery outcomes in patients with HHT. This retrospective cohort study used the Nationwide Readmissions Database to identify patients with HHT diagnosis on delivery between 2010 and 2021. The primary outcome was severe maternal morbidity (SMM). Secondary outcomes included nontransfusion SMM, preterm birth, stillbirth, prelabor rupture of membranes or preterm prelabor rupture of membranes, cesarean delivery, respiratory bleeding, cerebrovascular complications, patient disposition, and length of stay. Trends in the prevalence of HHT at delivery were assessed with logistic regression. Logistic regression analyses, adjusting for age, payer, zip code income, hospital size, and teaching status, were also used to produce adjusted relationships between HHT status and outcomes. The cohort of 21,698,861 delivered pregnancies corresponded to a national estimate of 44,325,599. Of those, 612 (national estimate: 1,265; 2.8 per 100,000) had a diagnosis of HHT. A steady rise in the HHT diagnosis rate during pregnancy from 2010 to 2021 (1.7 per 100,000 in 2010, 3.8 per 100,000 in 2021, p < 0.001 for trend) was seen. Patients with HHT were significantly more likely to experience SMM compared with patients without HHT (7.8 vs. 1.7%, adjusted relative risk [aRR]: 4.49 [95% confidence interval, CI: 3.06, 6.58]). Rates of preterm birth (14.2 vs. 8.5%, aRR: 1.57 [95% CI: 1.22, 2.03]), cesarean delivery (41.0 vs. 32.9%, aRR: 1.23 [95% CI: 1.07, 1.41]), respiratory bleeding (2.1 vs. <0.1%, aRR: 94.44 [56.64, 157.46]), and cerebrovascular complications (0.9 vs. <0.1%, aRR: 22.89 [9.89, 52.96]) were higher in patients with HHT than non-HHT patients. There was no difference in stillbirth rates between groups. Patients with HHT have higher rates of SMM and adverse delivery outcomes when compared with the baseline population. · There was a steady rise in the rates of HHT during pregnancy from 2010 to 2021.. · Patients with HHT are more likely to experience SMM.. · Patients with HHT are more likely to have a preterm delivery and cesarean delivery..

7819 Hypoglycemia with Hereditary Hemorrhagic Telangiextsia in a Boy After Liver Transplantation

Abstract Disclosure: H. Miyagi: None. M. Igarashi: None. E. Tanimoto: None. R. Horikawa: None. Introduction: Hereditary hemorrhagic telangiectasia (HHT) causes arteriovenous malformation (AVM) in liver, lung, and brain. It is not clear whether it also causes hypoglycemia. We show a case of HHT combined with hypoglycemia after liver transplantation, improved by nutrition management and growth hormone treatment. Case: 11 months old boy born from a mother with HHT was diagnosed as having with AVM prenatally. He was once operated for the liver AVM but developed a new collateral circulation which caused severe heart failure and lead to liver transplantation. He showed severe growth retardation and malnutrition. His body weight was 4.6 kg and height were 60 cm (-5.8 SD) when he was 1 year old, and blood test showed low albumin for 3 g/dL (3.4 - 4.7 g/dL), and total protein for 4 g/dL (5.7 - 7.5 g/dL). Hypoglycemia was found while switching his nutrition from parenteral to enteral nutrition after operation. His insulin was under 0.3 µU/mL when his blood glucose was 49 mg/dL IGF1 was 17 ng/mL (ref.11 - 149 ng/mL), suggested growth hormone (GH) deficiency. GH stimulation test showed blunted response. GH treatment was started. Other pituitary hormones were within normal range. Nutritional support was added using high-calory milk. After GH treatment, IGF1 level increased to 87 ng/mL. GH and nutritional management improved not only his weight and height gain but also his glycemic control. Discussion: Hypoglycemia may be caused by both GHD and malnutrition. GHD and low IGF1 might be caused by malnutrition. Retesting GH secretion after improvement of nutrition is planned to clarify his pituitary function. Presentation: 6/2/2024

Atypical venous drainage system and distinct vascular characteristics in pediatric intracerebral hemorrhage caused by multiple micro arteriovenous malformations.

Hemorrhagic brain micro-arteriovenous malformations (micro-AVMs) are considered to constitute a relatively significant portion of pediatric AVMs, though they are often associated with a low bleeding rate, as seen in hereditary hemorrhagic telangiectasia, which frequently involves multiple micro-AVMs. We present a rare case of a 10-year-old girl with multiple hemorrhagic micro-AVMs. Intraoperative findings during the emergency operation for hematoma evacuation and post-operative superselective angiography highlighted the unique angioarchitecture of three micro-AVMs (two lesions in the superficial areas and one lesion in the deep-seated area) and the atypical bleeding source due to the complex congestive venous drainage system. One micro-AVM was successfully occluded by a transarterial emboliozation, and remaining two micro-AVMs underwent gamma knife irradiation as a salvage therapy. Superselective angiography is crucial for detecting micro-AVMs, offering detailed insights into small, localized abnormal vascular drainage systems, and guiding therapeutic strategy. Additionally, micro-AVM-associated unique vascular hypersensitivity, such as vasospasm, requires careful consideration, as invasive procedures may significantly alter the visibility of the entire micro-AVM network.

Reduction of bleeding by cabozantinib in metastatic renal cell carcinoma with hereditary hemorrhagic telangiectasia

Reduction of bleeding by cabozantinib in metastatic renal cell carcinoma with hereditary hemorrhagic telangiectasia

Natural history and management outcomes of patients with ruptured Spetzler-Martin grade IV and V brain arteriovenous malformations.

The natural history of ruptured high Spetzler-Martin grade IV and V brain arteriovenous malformations (bAVMs) is underreported given the scarcity of this pathology, and decision-making for patients with bAVMs remains unclarified. In this study, the authors sought to shed light on this topic. Patients harboring ruptured high-grade bAVMs were identified from an institutional database spanning from 1990 to 2020. The authors examined outcomes of annual hemorrhagic risk in natural history and after treatment, follow-up hemorrhage rate, bAVM obliteration, follow-up modified Rankin Scale (mRS) score > 2, worsened mRS score, and mortality. After reviewing the charts of 1066 patients without hereditary hemorrhagic telangiectasia, 84 patients with ruptured high-grade bAVMs were included in the study for analysis. For cortical bAVMs, the annual risk of hemorrhage during natural history was 2.68%. Surgery decreased the risk to 0.74%, while radiosurgery increased the risk to 5.35%, and embolization only increased the risk to 16.96%. For deep-seated high-grade bAVMs, the annual risk of hemorrhage during natural history was 8.37%. Radiosurgery decreased the risk to 3.11%, surgery decreased the risk to 5.25%, and embolization only increased the risk to 22.33%. Poisson regression analysis demonstrated that embolization only increased the risk of hemorrhage in cortical bAVMs (rate ratio 4.745, 95% CI 1.365-12.819; p = 0.005) and deep-seated bAVMs (rate ratio 6.290, 95% CI 0.997-21.932; p = 0.013). Logistic regression analysis showed that surgery (OR 52.000, 95% CI 8.083-1046.127; p = 0.004) and radiosurgery (OR 11.142, 95% CI 1.804-217.650; p = 0.029) were predictors of obliteration in cortical and deep-seated bAVMs, respectively. The proportions of patients experiencing a worsened mRS score, a follow-up mRS score > 2, and mortality were similar between conservative and treatment groups. The natural history of cortical ruptured high-grade bAVMs bears a risk similar to that of incidental bAVMs, whereas deep-seated ruptured high-grade bAVMs have an increased risk of hemorrhage. With extremely prudent patient selection, surgery might be a viable option for cortical bAVMs to obliterate the bAVM and reduce hemorrhagic risk, while preserving functional status. Radiosurgery might be beneficial to lower hemorrhagic risk in deep-seated bAVMs. Embolization as a single modality should be avoided as it provides no benefit to reduce hemorrhagic risk.

Somatic mutations in arteriovenous malformations in hereditary hemorrhagic telangiectasia support a bi-allelic two-hit mutation mechanism of pathogenesis

Hereditary hemorrhagic telangiectasia (HHT) is an inherited disorder of vascular malformations characterized by mucocutaneous telangiectases and arteriovenous malformations (AVMs) in internal organs. HHT is caused by inheritance of a loss of function mutation in one of three genes. Although individuals with HHT are haploinsufficient for one of these genes throughout their entire body, rather than exhibiting a systemic vascular phenotype, vascular malformations occur as focal lesions in discrete anatomic locations. The inconsistency between genotype and phenotype has provoked debate over whether haploinsufficiency or a different mechanism gives rise to the vascular malformations. We previously showed that HHT-associated skin telangiectases develop by a two-hit mutation mechanism in an HHT gene. However, somatic mutations were identified in only half of the telangiectases, raising the question whether a second-hit somatic mutation is a necessary (required) event in HHT pathogenesis. Here, we show that another mechanism for the second hit is loss of heterozygosity across the chromosome bearing the germline mutation. Secondly, we investigate the two-hit mutation mechanism for internal organ AVMs, the source of much of the morbidity of HHT. Here, we identified somatic molecular genetic events in eight liver telangiectases, including point mutations and a loss of heterozygosity event. We also identified somatic mutations in one pulmonary AVM and two brain AVMs, confirming that mucocutaneous and internal organ vascular malformations undergo the same molecular mechanisms. Together, these data argue that bi-allelic loss of function in an HHT gene is a required event in the pathogenesis of HHT-associated vascular malformations.

Molecular and Functional Cargo of Plasma-Derived Exosomes in Patients with Hereditary Hemorrhagic Telangiectasia.

Background: Hereditary Hemorrhagic Telangiectasia (HHT) is a genetic disorder leading to frequent bleeding in several organs. As HHT diagnosis is demanding and depends on clinical criteria, liquid biopsy would be beneficial. Exosomes from biofluids are nano-sized vesicles for intercellular communication. Their cargo and characteristics represent biomarkers for many diseases. Here, exosomes of HHT patients were examined regarding their biosignature. Methods: Exosomes were isolated from the plasma of 20 HHT patients and 17 healthy donors (HDs). The total exosomal protein was quantified, and specific proteins were analyzed using Western blot and antibody arrays. Human umbilical vein endothelial cells (HUVECs) co-incubated with exosomes were functionally examined via immunofluorescence, proliferation, and scratch assay. Results: The levels of the angiogenesis-regulating protein Thrombospondin-1 were significantly higher in HHT compared to HD exosomes. Among HHT, but not HD exosomes, a negative correlation between total exosomal protein and soluble Endoglin (sENG) levels was found. Other exosomal proteins (ALK1, ALK5) and the particle concentration significantly correlated with disease severity parameters (total consultations/interventions, epistaxis severity score) in HHT patients. Functionally, HUVECs were able to internalize both HD and HHT exosomes, inducing a similar change in the F-Actin structure and a reduction in migration and proliferation. Conclusions: This study provided first insights into the protein cargo and function of HHT-derived exosomes. The data indicate changes in sENG secretion via exosomes and reveal exosomal Thrombospondin-1 as a potential biomarker for HHT. Several exosomal characteristics were pointed out as potential liquid biomarkers for disease severity, revealing a possible new way of diagnosis and prognosis of HHT.

The Role of Thalidomide and Its Analogs in the Treatment of Hereditary Hemorrhagic Telangiectasia: A Systematic Review.

Background: Hereditary hemorrhagic telangiectasia (HHT) is a disease characterized by arteriovenous malformations and telangiectases, in which the endothelium and immune system play a role in the pathophysiology. Therefore, treatments with antiangiogenic properties which are also regarded as immunomodulators were demonstrated to play an important role in treatment. This systematic review aimed to gather the accumulated information of the use of thalidomide and its analogs in the treatment of HHT. Methods: In this systematic review, publications that were published up to March 2024 and met the inclusion criteria were compiled using the keywords 'thalidomide', 'lenalidomide', 'pomalidomide', 'immunomodulatory drugs' and 'HHT' in Medline and Scholars databases. Results: A total of 53 articles were evaluated and 15 were included in the study. Thalidomide was the predominant used agent and was observed to be used in patients with ages ranging from 37 to 77 years, with doses ranging from 50 to 200 mg daily, and the mean follow-up period was observed to be 6-60 months. Assessments regarding efficacy were based on the epistaxis severity score (ESS), hemoglobin level, and transfusion independence. While thalidomide showed significant efficacy, it also had an adverse event rate of any severity of up to 85% of patients. Use of lenalidomide to control bleeding in HHT was reported in a single case report, while the use of pomalidomide was observed to be investigated in Phase 1 and Phase 2 studies in patients aged 48 to 70 years, with doses ranging from 1 to 5 mg daily for 6-24 months. This treatment was reported to provide significant improvement in hemoglobin levels and ESS. Adverse events of any severity were observed at a frequency of 60-66%. Conclusions: Antiangiogenic agents such as thalidomide, lenalidomide, and pomalidomide may be effective in managing HHT. However, further studies are needed to optimize the timing, dose, and sequence.

STUDY OF SOMATIC AND GERMINAL MUTATIONS IN ARTERIOVENOUS MALFORMATIONS OF THE BRAIN USING WHOLE EXOME SEQUENCING

Rare vascular lesions known as brain arteriovenous malformations (bAVMs) are caused by shunts between cerebral arteries and veins that do not involve the capillary bed. The majority of bAVMs do not cause any symptoms, however some can be controlled by seizures and result in potentially fatal brain hemorrhages. Over the past ten years, significant advancements in our understanding of bAVM pathogenesis have been accomplished, primarily through the use of genome sequencing and biomolecular analysis. An autosomal dominant vascular disorder called Hereditary Hemorrhagic Telangiectasia (HHT, also known as Rendu-Osler-Weber Syndrome) affects about 1 in 5000 people globally and is associated with about 5% of brain AVMs, while the remaining 95% are due to sporadic mutations. The major aim of the project is to investigate genetic causes of sporadic forms of AVMs in the brain by means of whole-exome sequencing of tissues with AVM lesions and blood samples. Analysis of somatic mutations will broaden the understanding of AVM pathogenesis. This study was carried out in accordance with the Declaration of Helsinki's tenets and approved by the National Center of Biotechnology 's ethics committee (№9, 7 November 2023, ) Astana). Based on clinical data, the age range of the patients at the onset of the disease also encompassed 25 to 40 years. To confirm the diagnosis, MRI and CAG data were used to validate the diagnosis. Each patient completed a specially designed questionnaire with medical information (such as age of debut and type of course) and demographic data (such as age, gender, and nationality). Three patients were classified as having a Spetzler-Martin grade II, while one patient was categorized as grade III. The sizes of arteriovenous malformations (AVMs) varied from 0 to 3 mm in one patient (grade II) to 3 to 6 mm in three patients (grades II-III). AVM tissue specimens were obtained during clinically necessary procedures. Brain AVM tissues were collected during surgery, which involved trepanation and excision of the AVM. Blood samples were also collected from these patients. Both DNA and RNA were isolated from these tissue and blood samples for subsequent exome sequencing an. Qubit 2.0 fluorometer was employed for more precise determination of DNA concentration, given that the nucleic acids will be utilized in future whole exome sequencing analysis. Whole exome sequencing was performed on six samples (blood and tissue) by Novaseq 6000 (Illumina). The annotated results were analyzed for the presence of single-nucleotide polymorphisms (SNP) and insertion-deletion mutations (Indels) between DNAs from the AVM tissue sample and blood. The GATK workflow was used for the analysis and annotation of the raw data, and vcf files were generated. Then, the variants were filtered for a quality ≥ 30 in Excel 1st blood 117554, 1st tissue 114715; 2nd blood 112972, 2nd tissue 116022; 3rd blood 112859, 3rd tissue 117168 and genotype differences between tissue and blood DNA samples 1st blood 114512, 1st tissue 111682; 2nd blood 110614, 2nd tissue 111982; 3rd blood 110564, 3rd tissue 112805. After selecting only non-synonymous, frameshift insertions and deletions variants with different genotypes in the blood and tissue samples, 1st blood 279, 1st tissue 277; 2nd blood 279, 2nd tissue 271; 3rd blood 275, 3rd tissue 268 variations were observed. Analysis of whole-exome data continues.

Hereditary hemorrhagic telangiectasia - pediatric review.

Hereditary hemorrhagic telangiectasia (HHT) diagnostic and management approach for pediatrics underwent significant advances over the last couple of years. In 2020, new guidelines for HHT were published that included a pediatric section thus attracting special focus into the childhood presentation. Curacao criteria are specific, but not sensitive enough in children. Genetic testing is encouraged for all family members even if asymptomatic. Standardized scoring for epistaxis is strongly encouraged, as it allows monitoring and can stratify therapeutic approaches. Early screening for pulmonary and brain visceral arteriovenous malformations (AVMs) in pediatric patients with confirmed genetic alterations of HHT should be instituted. Graded trans-esophageal echocardiogram with agitated saline contrast can be used as screening method for pulmonary AVMs. As pulmonary AVMs can develop throughout lifetime, guidelines recommend repeated screening even in asymptomatic patients at least every 5 years. Signs of stroke in childhood are more subtle than in adults. Cerebral imaging in early childhood can identify brain AVMs that may benefit from early intervention. Embolization of high-risk pulmonary and cerebral AVMs should be performed at specialized centers even at pediatric age. One or two classic HHT telangiectasia can be considered diagnostic in children. Antibiotic prophylaxis with dental procedures continues to be recommended.

Hereditary Hemorrhagic Telangiectasia (Osler's Disease): Systemic, Interdisciplinary, Relatively Common–and Often Missed.

Hereditary hemorrhagic telangiectasia (HHT, Rendu-Osler-Weber disease, or Osler's disease for short) is a systemic disease that can severely impair the quality of life and that requires interdisciplinary treatment. Among rare diseases, it is relatively common, with a prevalence of approximately 1/5000. This review is based on publications retrieved by a selective literature search, including the two international guidelines on clinically relevant aspects of HHT. On average, about two decades elapse between the initial symptoms and the diagnosis of HHT. 95% of patients have nosebleeds; these usually begin before age 20 but can occur at any time, from infancy to old age. The diagnosis is usually made on clinical grounds on the basis of the characteristic telangiectases, a positive family history, and possible involvement of the gastrointestinal tract, lungs, liver, and brain. Nosebleeds can sometimes be reduced by outpatient measures including counseling on keeping the nose moist (expert consensus), self-application of a nasal packing (which improves the quality of life, according to an online survey), and the prescription of tranexamic acid (reduction of nosebleeds from 17.3% [5.5; 27.6] to 54%). In particular, screening (expert consensus) for pulmonary vascular malformations (frequency 10-50%) can prevent many adverse outcomes. If pulmonary vascular malformations cannot be ruled out, antibiotic prophylaxis is recommended before medical procedures that can cause bacteremia (expert consensus). Broad awareness of the condition, early diagnosis, and interdisciplinary treatment improve the quality of life and ultimate outcome of persons with HHT. Nevertheless, there are few options supported by good evidence for the appropriate treatment of this rare, often serious disease.