Cutaneous Collagenous Vasculopathy: A Retrospective Clinical and Histopathologic Analysis of 34 Cases.

BACKGROUND: Cutaneous collagenous vasculopathy (CCV) is a rare acquired microangiopathy that commonly affects middle-aged, fair-skinned individuals. It presents with telangiectatic lesions involving the lower extremities. Histologic analysis is mandatory for diagnosis. OBJECTIVES: To describe and characterize the patients diagnosed with CCV at the Mayo Clinic. METHODS: A multicenter retrospective observational analysis was performed on patients with a clinical and histological diagnosis of CCV at the Mayo Clinic in Florida, Arizona, and Rochester from January 2000 to October 2023. RESULTS: The study included 34 patients, 22 (64.7%) females. The median age at diagnosis was 52 years (range, 12-80 years). CCV lesions were found to affect the lower extremities in 29 (85.3%) patients, followed by the trunk in 14 (41.2%). Nineteen (55.9%) patients presented 1 concomitant medical condition, 8 (23.5%) 2 conditions, and 5 (14.7%) 3 or more medical conditions, such as arterial hypertension 10 (29.4%), type 2 diabetes mellitus 3 (8.8%), hyperlipidemia 3 (8.8%), cardiac disease 3 (8.8%), and hematologic malignancy 3 (8.8%). Thirty-one patients (91.2%) were taking medications, with 19 (55.9%) taking 3 or more. Pathology staining revealed periodic acid-Schiff positivity in 23 of 34 cases (67.6%), and collagen IV in 26 of 34 cases (47.1%). Treatments included pulsed dye laser 3 (8.8%) and topical sirolimus 1 (2.9%). CONCLUSIONS: CCV is an uncommon microangiopathy that affects pediatric, middle-aged, and elderly patients. It involves the lower extremities, trunk, and upper extremities. Patients often present with associated metabolic and cardiovascular conditions and are usually taking at least 1 medication. Treatment options are limited.

Criteria for PAVM Reintervention.

Background/Objectives: To propose criteria for retreating previously embolized PAVMs and determining the effectiveness of the criteria to prevent paradoxical embolization. Methods: A retrospective review of patients with PAVMs treated at a single HHT center of excellence between 1 January 2013, and 10 September 2023, was performed. Patients with PAVM recurrence were either retreated or observed based on the following criteria for PAVM reintervention: 1. Embolic device(s) not creating a sufficiently dense matrix, such that a channel through them may be >/ 2 mm; 2. Accessory feeding artery or pulmonary collateral >/ 2 mm; 3. Hemoptysis in a patient with no other explanation. Results: A total of 438 PAVMs were treated in 151 patients, including 106 patients with definite, 14 possible, and 31 doubtful HHT. Post-embolization PAVM recurrence occurred in 36 patients (36/151, 23.8%), including 15 patients (15/151, 9.9%) with 22 PAVMs (22/438, 5.0%) meeting criteria for reintervention. A total of 21 patients (21/151, 13.9%) with recurrence did not meet reintervention criteria and were therefore observed. Pre-treatment paradoxical embolization occurred in 36 patients (36/151) for a lifetime prevalence rate of 23.7%. Post-treatment paradoxical embolization did not occur in any patients following PAVM embolization (0/151). There was one case of iatrogenic paradoxical embolization in a patient being treated for systemic collateral reperfusion and hemoptysis. However, this was not included given that it was not a spontaneous event. Conclusions: Utilizing modern embolization techniques and devices, the proposed reintervention criteria, and screening intervals, paradoxical embolizations can be effectively prevented in patients with PAVMs.

Bilateral Pulmonary Arteriovenous Malformations: Challenges in a Rare and Complex Case.

Pulmonary arteriovenous malformations (PAVMs) are abnormal vascular connections between the pulmonary arteries and pulmonary veins. Despite their relatively uncommon incidence, PAVMs should be considered in the differential diagnosis of children presenting with cyanosis due to the life-threatening complications posed by paradoxical emboli. The primary management approach involves eliminating the abnormal connections, either through surgical or endovascular methods. We present a case of a five-year-old boy who was seen in the Outpatient Department with cyanosis of the lips and nail beds persisting for eight months. On examination, grade 3 clubbing was noted. Imaging and subsequent angiography revealed multiple bilateral diffuse AVMs, which were treated using an endovascular approach.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Pazopanib in treatment of Hereditary Hemorrhagic Telangiectasia-related epistaxis and gastrointestinal bleeding.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a bleeding disorder characterized by arteriovenous malformations (AVMs), commonly presenting with epistaxis and gastrointestinal bleeding. Bleeding symptoms may be difficult to manage and may become life-threatening, with many patients developing dependence on parenteral iron and/or blood transfusion. There is a growing body of evidence that antiangiogenic therapies may be effective in management of bleeding symptoms, presumably targeting pathogenic HHT pathways such as vascular endothelial growth factor (VEGF) receptor. OBJECTIVES: To report single-center, retrospective real-world use of pazopanib, an orally administered tyrosine kinase inhibitor that blocks VEGF receptors, in six patients with HHT-associated epistaxis and/or gastrointestinal (GI) bleeding. PATIENT/METHODS: A retrospective observational analysis was performed to assess the safety/efficacy of pazopanib use in patients with confirmed HHT-associated epistaxis and/or GI bleeding between 01 January 2019 and 14 June 2023 The Indiana Hemophilia and Thrombosis (IHTC) institutional EMR was queried for HHT patients who were treated with pazopanib for >3 months. Patient data were obtained from patient documentation, physician/nursing notes, and on-call documentation Institutional IRB approval was obtained for data pull as an exempt study RESULTS AND CONCLUSIONS: Our observations on the real-world use of pazopanib in six HHT patients with moderate to severe bleeding showed improvement in hemoglobin levels, with reduction in iron infusions and red blood cell transfusion requirement. Pazopanib may be a reasonable option for patients with HHT with epistaxis or gastrointestinal bleeding that are refractory to standard treatment.

Validation of a Photonumeric Scale for Evaluation of Telangiectasia in Rosacea.

BACKGROUND: Telangiectasia is a prominent feature of rosacea leading to a high demand for effective treatment. To ensure consistent clinical and scientific evaluations and assess treatment response accurately, standardized assessment tools are necessary for grading the severity of telangiectasia. However, no validated grading scales for this condition are currently available. AIM: To develop and validate a photonumeric scale for assessing the severity of telangiectasia in rosacea patients. METHODS: The five-point photonumeric Telangiectasia in Rosacea Severity Assessment (TRoSA) scale was developed for the severity of telangiectasia in rosacea. Sixteen experts participated in the validation process, evaluating 50 images of rosacea patients in two rounds. Interrater and intrarater reliability were analyzed using the intraclass correlation coefficient (ICC) and weighted kappa, respectively. RESULTS: Interrater reliability was found to be "almost perfect" in both validation rounds (Round 1: ICC 0.847; Round 2: ICC 0.828). The mean weighted kappa indicated "substantial" intrarater reliability between the two rounds with a weighted kappa of 0.719. A bubble plot of the two rounds illustrated a diagonal order, confirming the consistency of the intrarater agreement. CONCLUSIONS: The TRoSA scale demonstrated high interrater and intrarater reliability indicating that it is a consistent and reproducible tool for grading the severity of telangiectasia in rosacea. This scale can standardize clinical assessments, assisting in diagnosis, treatment planning, and evaluation of therapeutic efficacy.

Pioglitazone as a Possible Treatment for Ataxia-Telangiectasia.

Ataxia-telangiectasia (AT) is a rare autosomal recessive disorder characterized by immunodeficiency, progressive cerebellar ataxia, and an increased malignancy risk. Cells derived from individuals with AT show multiple defects, including high oxidant and ionizing radiation sensitivities, poor DNA repair, low iron-sulfur cluster levels, and low reduced glutathione. The clinical course of AT is progressive and unrelenting, with most individuals having a survival time of approximately twenty-five years. Presently, AT has no effective treatments, and most patients receive supportive care only. Recently, pioglitazone, a thiazolidinedione class used to treat type 2 diabetes, has been demonstrated to exert beneficial effects on AT cells and on diabetic individuals with AT. Here, I will discuss the possible molecular mechanisms of pioglitazone's favorable effects on the AT phenotype and why it may have utility in treating some aspects of AT.

Hereditary haemorrhagic telangiectasias with recurrent ischemic stroke hinted by manganese deposition in the basal ganglia: a case report and literature review.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant inherited vascular disorder that can involve multiple organs, thus can be associated with so many clinical departments that proper screening and diagnosis of HHT are needed for providing better management of both patients and their family members. CASE PRESENTATION: We present a 58-year-old female patient with recurrent paradoxical brain embolism due to HHT. She received aspirin therapy and underwent pulmonary arteriovenous malformation embolization, recovering well and discharged 3 days postoperatively. Though ischemic stroke caused by HHT-induced vascular disorders has been reported, our patient presented with both recurrent paradoxical brain embolisms and radiologic findings of bilateral globus pallidus manganese deposition at the same time, a combination rarely reported. We also review the literature on the clinical features and management of HHT for prompt diagnosis of this genetic disease behind paradoxical embolism. CONCLUSIONS: When patients with ischemic stroke, especially recurrent ischemic stroke, have combined arteriovenous malformations (AVMs) in single or multiple organs, or clues for AVMs like manganese deposition in globus pallidus, genetic diseases such as HHT may be the reason for ischemic stroke and shouldn't be missed in the evaluation of embolic sources.

Graded Transthoracic Contrast Echocardiography After Pulmonary Arteriovenous Malformation Embolization: Can Chest CT Be Avoided in Patients With a Low-Grade Shunt?

BACKGROUND: Pulmonary arteriovenous malformations (PAVMs) are direct connections between the pulmonary artery and vein, creating a right-to-left shunt (RLS). Embolization is indicated to prevent complications. Guidelines recommend follow-up chest CT scans to confirm persistent occlusion and embolization of all treatable PAVMs. Graded transthoracic contrast echocardiography (TTCE) after PAVM embolization may offer a reliable alternative in a subgroup of patients while preventing radiation exposure. RESEARCH QUESTION: Can TTCE predict the need for additional embolotherapy in the postembolization population as accurately as it does in the treatment-naive population?. STUDY DESIGN AND METHODS: Since 2018, follow-up after PAVM embolization at our study institution includes both TTCE and chest CT scan after 6 to 12 months and every 3 to 5 years thereafter. Patients who underwent at least 1 follow-up TTCE and chest CT scan were included. The indication for additional embolotherapy was discussed in a multidisciplinary team meeting. The primary outcome was the indication for additional embolotherapy in each RLS grade. Additionally, the association between the RLS grade and indication for additional embolotherapy was investigated. RESULTS: A total of 339 patients with 412 embolization procedures were included; median time to follow-up TTCE was 7.5 months. An RLS was present in 399 postembolization TTCEs (97%): RLS grade 1 in 93 patients (23%), grade 2 in 149 patients (36%) and grade 3 in 157 patients (38%). In patients with RLS grades 0 and 1, no treatable PAVMs were found on CT scan. In patients with RLS grades 2 and 3, 22 (15%) and 72 (46%) underwent additional embolization. INTERPRETATION: This study shows chest CT scan might be forgone in patients with RLS grades 0 and 1 after PAVM embolization.

A Gene Expression Signature that Predicts Gastric Cancer Sensitivity to PARP Inhibitor Therapy.

BACKGROUND/AIM: Biomarkers indicating sensitivity to poly ADP-ribose polymerase (PARP) inhibitors have not yet been identified in gastric cancer. PARP inhibitors target homologous recombination deficiency (HRD); however, homologous recombination (HR) induces complex changes in gene expression, which makes it difficult to identify reliable biomarkers. In this study, we identified a multi-gene expression signature as a marker of PARP inhibitor sensitivity in gastric cancer. MATERIALS AND METHODS: Seven gastric cancer cell lines were evaluated for susceptibility to PARP inhibitors using a growth inhibition assay. Gene expression profiling (GEP) was used to identify differentially expressed genes between PARP inhibitor-sensitive and -resistant cell lines. The resulting gene set was subjected to cluster analysis using tumor samples from 250 patients who underwent gastrectomy for primary gastroesophageal junction and gastric adenocarcinoma. HRD was defined as a truncating mutation in one or more of 22 HR-related genes and HRD scores were calculated using whole-exome sequencing data. RESULTS: In the growth inhibition assays, the HGC27 and HSC39 cell lines were sensitive to the PARP inhibitors, olaparib, and rucaparib, and were significantly correlated with the GEP results. Seven (2.8%) patients harbored truncating mutations in HR-related genes. A gene expression signature based on the top 100 high and low differentially expressed genes between sensitive and resistant cell lines revealed a patient cluster with a high prevalence of HR-related gene mutations and high HRD scores. CONCLUSION: The 100-gene expression signature identified in this study may serve as a valuable predictive biomarker for PARP inhibitor sensitivity in gastric cancer.

53BP1 regulates the self-renewal ability of neural stem/progenitor cells through modulating mitochondrial homeostasis.

The regulation of intracellular reactive oxygen species (ROS) levels is important for maintaining the self-renewal ability of neural stem/progenitor cells (NSCs). In this study, we demonstrate that 53BP1, a DNA damage response factor known to facilitate the repair of DNA double-strand breaks, supports the maintenance of NSC stemness. ReNcell VM human NSCs with depleted 53BP1 exhibited reduced self-renewal ability compared with control NSCs, as revealed by a decrease in neurosphere size and an increase in differentiation into neural or glial cells within an NSC culture. Furthermore, 53BP1 depletion elevated cellular ROS levels, accompanied by mitochondrial abnormalities. The reduced self-renewal ability and elevated ROS levels in 53BP1-deficient NSCs were restored with the treatment of a radical scavenger, N-acetyl-l-cysteine. In addition, we investigated the functional relationship in the NSC self-renewal ability between 53BP1 and ataxia-telangiectasia mutated (ATM) or forkhead box O3a (FOXO3a), factors required for mitochondrial homeostasis, and the maintenance of NSC stemness. We found that ATM inhibition or FOXO3a deficiency, in addition to 53BP1 deficiency, did not induce further NSC stemness impairment. Collectively, our findings show that 53BP1, by cooperatively functioning with ATM and FOXO3a, supports the maintenance of NSC stemness by modulating mitochondrial homeostasis.

Repeated radon exposure induced ATM kinase-mediated DNA damage response and protective autophagy in mice and human bronchial epithelial cells.

OBJECTIVE: Radon ( 222 Rn) is a naturally occurring radioactive gas that has been closely linked with the development of lung cancer. In this study, we investigated the radon-induced DNA strand breaks, a critical event in lung carcinogenesis, and the corresponding DNA damage response (DDR) in mice and human bronchial epithelial (BEAS-2B) cells. METHODS: Biomarkers of DNA double-strand breaks (DSBs), DNA repair response to DSBs, ataxia-telangiectasia mutated (ATM) kinase, autophagy, and a cell apoptosis signaling pathway as well as cell-cycle arrest and the rate of apoptosis were determined in mouse lung and BEAS-2B cells after radon exposure. RESULTS: Repeated radon exposure induced DSBs indicated by the increasing expressions of γ-Histone 2AX (H2AX) protein and H2AX gene in a time and dose-dependent manner. Additionally, a panel of ATM-dependent repair cascades [i.e. non-homologous DNA end joining (NHEJ), cell-cycle arrest and the p38 mitogen activated protein kinase (p38MAPK)/Bax apoptosis signaling pathway] as well as the autophagy process were activated. Inhibition of autophagy by 3-methyladenine pre-treatment partially reversed the expression of NHEJ-related genes induced by radon exposure in BEAS-2B cells. CONCLUSIONS: The findings demonstrated that long-term exposure to radon gas induced DNA lesions in the form of DSBs and a series of ATM-dependent DDR pathways. Activation of the ATM-mediated autophagy may provide a protective and pro-survival effect on radon-induced DSBs.

An Unusual Case of Metronidazole-induced Encephalopathy in a Patient with Hereditary Hemorrhagic Telangiectasia.

Metronidazole-induced encephalopathy (MIE) is a rare toxic encephalopathy. We describe a reversible MIE case in a patient with hereditary hemorrhagic telangiectasia (HHT), treated with metronidazole for brain abscess, who developed dizziness, weakness, dysarthria, and severe dysmetria. His Magnetic Resonance Imaging (MRI) brain revealed bilateral, symmetric lesions in bilateral symmetrical regions of increased intensity in the medullary olives, cerebellar dentate nuclei, and the dorsal pons, all characteristic of MIE. Upon metronidazole discontinuation, the patient experienced significant symptom improvement, with subsequent MRI showing resolution of the lesions.

Osler-Weber-Rendu Syndrome as a Rare Cause of Liver Cirrhosis.

It is essential to comprehend the clinical manifestations of hereditary hemorrhagic telangiectasia (HHT), also known as Osler-Weber-Rendu syndrome. This autosomal dominant vascular disorder presents with distinct symptoms, including mucocutaneous telangiectasia, epistaxis, gastrointestinal bleeding, and iron deficiency anemia. Furthermore, arteriovenous malformations (AVMs) commonly occur in the pulmonary, hepatic, and cerebral circulations. Hepatic involvement may be uncommon, depending on the subtype of HHT. HHT is a rare cause of liver cirrhosis. We present the case of a 59-year-old female patient referred to a hepatology consultation for the etiological study of liver disease that progressed to liver cirrhosis. From the study carried out, the presence of hepatic arteriovenous shunt was detected, which raised the suspicion of HHT, with the genetic study confirming the diagnosis. In this case, we intend to demonstrate the diagnostic difficulty of this entity, which led to a long time between the initial manifestation and the diagnostic conclusion. We would also like to highlight the importance of imaging and genetic studies in determining the etiology of the disease.

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.

Macular telangiectasia type 2 in a patient with Down syndrome: A possible association.

Purpose: Down syndrome (DS) is one of the most prevalent genetic diseases associated with a variety of ophthalmic disorders, including reported retinal abnormalities. Macular telangiectasia type 2 (MacTel 2) is a late-onset neurodegenerative retinal disease with a substantial genetic component. We hereby describe a case of a female with DS who presented with MacTel 2, and we discuss the possible pathways associating both entities. Observation: We report the case of a 49-year-old female with a medical history of DS and hydroxychloroquine (HCQ) intake. She was referred for HCQ retinal toxicity screening. The multimodal imaging revealed a temporal perifoveal gray area with crystal deposits on multicolor fundoscopy with parafoveal outer retinal atrophy and ellipsoid zone loss with inner retinal cavitations in both eyes on the optical Coherence Tomography (OCT) B scan. The corresponding swept-source OCT angiography confirmed the presence of bilateral macular telangiectasia. Conclusion and importance: Metabolic pathways including serine/glycine and sphingolipids are incriminated in both entities' pathogenesis suggesting a possible association, hence, the importance of raising awareness of this association. More cases are likely to be found since DS patients currently have a nearly normal lifespan. Additional retinal examination of DS adults is then necessary to look for signs of MacTel 2.

Rapid Remission With Upadacitinib in a Child With Refractory Crohn's Disease and ATM Mutation: A Case Report.

Managing pediatric Crohn's disease (PCD) presents challenges due to severe complications and higher biologic therapy needs. Transitioning from anti-tumor necrosis factor agents to off-label therapies adds complexity. Although upadacitinib has demonstrated efficacy and tolerability in adult inflammatory bowel disease and pediatric atopic dermatitis, there are limited data for its application in PCD. This case report delineates successful remission with upadacitinib in a child with CD refractory to infliximab, ustekinumab, adalimumab, thalidomide, and prednisone. Notably, the patient carried an ataxia telangiectasia mutated (ATM) gene mutation. These findings provide valuable evidence for PCD management and highlight the potential benefits of upadacitinib in this population.

Innovations in the management of epistaxis secondary to hereditary hemorrhagic telangiectasia: our evolution to injection sclerotherapy as the treatment of choice.

Introduction: We compared the efficacy of intralesional sclerotherapy using 3% sodium tetradecyl sulfate with non-sclerotherapy-based treatments for Hereditary Hemorrhagic Telangiectasia-associated epistaxis management. Methodology: This is a retrospective study of patients who underwent surgical intervention for HHT-associated epistaxis management from 01/2010-02/2024. Patients undergoing sclerotherapy with intralesional 3% sodium tetradecyl sulfate were included in the sclerotherapy group and others undergoing conventional non-sclerotherapy-based procedures in the non-sclerotherapy group. Outcomes like breakthrough epistaxis, emergency visits, intra-op blood loss, blood transfusions, and procedure complications in the 3-month perioperative period were compared. Results: Twenty-three patients who underwent 74 intranasal procedures were identified. In the sclerotherapy group, 17 patients underwent 47 procedures. In the non-sclerotherapy group, 10 patients underwent 27 procedures. Till the 3rd post-treatment month, fewer breakthrough epistaxis episodes were observed after sclerotherapy procedures (13/47) vs. non-sclerotherapy procedures (14/27); (p = 0.037). Intraoperative blood loss was significantly lower during sclerotherapy (median: 10 ml) vs. non-sclerotherapy procedures (median: 50 ml); p < 0.001. The time interval between successive procedures was not significantly different in the sclerotherapy (median 6.5 months) vs. the non-sclerotherapy group (median 3.5 months); p = 0.13. Nasal crusting was the most common complication in the sclerotherapy group (36.9%). Two patients in each group had new onset septal perforation, none of the patients had vision loss or cerebrovascular accident. One emergency department visit was reported in the sclerotherapy group vs. 7 (in 3 patients) in the non-sclerotherapy group. Conclusions: Compared to non-sclerotherapy treatments, intralesional sclerotherapy for epistaxis in HHT is more effective in decreasing breakthrough epistaxis, and has lower intraoperative blood loss.

MicroRNA dysregulation in ataxia telangiectasia.

Introduction: Ataxia telangiectasia (AT) is a rare disorder characterized by neurodegeneration, combined immunodeficiency, a predisposition to malignancies, and high clinical variability. Profiling of microRNAs (miRNAs) may offer insights into the underlying mechanisms of complex rare human diseases, as miRNAs play a role in various biological functions including proliferation, differentiation, and DNA repair. In this study, we investigate the differential expression of miRNAs in samples from AT patients to identify miRNA patterns and analyze how these patterns are related to the disease. Methods: We enrolled 20 AT patients (mean age 17.7 ± 9.6 years old) and collected clinical and genetic data. We performed short non-coding RNA-seq analysis on peripheral blood mononuclear cells (PBMCs) and fibroblasts to compare the miRNA expression profile between AT patients and controls. Results: We observed 42 differentially expressed (DE)-miRNAs in blood samples and 26 in fibroblast samples. Among these, three DE-miRNAs, miR-342-3p, miR-30a-5p, and miR-195-5p, were further validated in additional AT samples, confirming their dysregulation. Discussion: We identified an AT-related miRNA signature in blood cells and fibroblast samples collected from a group of AT patients. We also predicted several dysregulated pathways, primarily related to cancer, immune system control, or inflammatory processes. The findings suggest that miRNAs may provide insights into the pathophysiology and tumorigenesis of AT and have the potential to serve as useful biomarkers in cancer research.

Generation of an Isogenic Hereditary Hemorrhagic Telangiectasia Model via Prime Editing in Human Induced Pluripotent Stem Cells.

Prime editing (PE) is a recently developed genome-editing technique that enables versatile editing. Despite its flexibility and potential, applying PE in human induced pluripotent stem cells (hiPSCs) has not been extensively addressed. Genetic disease models using patient-derived hiPSCs have been used to study mechanisms and drug efficacy. However, genetic differences between patient and control cells have been attributed to the inaccuracy of the disease model, highlighting the significance of isogenic hiPSC models. Hereditary hemorrhagic telangiectasia 1 (HHT1) is a genetic disorder caused by an autosomal dominant mutation in endoglin (ENG). Although previous HHT models using mice and HUVEC have been used, these models did not sufficiently elucidate the relationship between the genotype and disease phenotype in HHT, demanding more clinically relevant models that reflect human genetics. Therefore, in this study, we used PE to propose a method for establishing an isogenic hiPSC line. Clinically reported target mutation in ENG was selected, and a strategy for PE was designed. After cloning the ENGineered PE guide RNA, hiPSCs were nucleofected along with PEmax and hMLH1dn plasmids. As a result, hiPSC clones with the intended mutation were obtained, which showed no changes in pluripotency or genetic integrity. Furthermore, introducing the ENG mutation increased the expression of proangiogenic markers during endothelial organoid differentiation. Consequently, our results suggest the potential of PE as a toolkit for establishing isogenic lines, enabling disease modeling based on hiPSC-derived disease-related cells or organoids. This approach is expected to stimulate mechanistic and therapeutic studies on genetic diseases.a.