Further characterization of clinical and laboratory features occurring in VEXAS syndrome in a large-scale analysis of multicenter case-series of 116 French patients

Clonal Hematopoiesis, Inflammation, and Hematologic Malignancy

Somatic or acquired mutations are postzygotic genetic variations that can occur within any tissue. These mutations accumulate during aging and have classically been linked to malignant processes. Tremendous advancements over the past years have led to a deeper understanding of the role of somatic mutations in benign and malignant age-related diseases. Here, we review the somatic mutations that accumulate in the blood and their connection to disease states, with a particular focus on inflammatory diseases and myelodysplastic syndrome. We include a definition of clonal hematopoiesis (CH) and an overview of the origins and implications of these mutations. In addition, we emphasize somatic disorders with overlapping inflammation and hematologic disease beyond CH, including paroxysmal nocturnal hemoglobinuria and aplastic anemia, focusing on VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Finally, we provide a practical view of the implications of somatic mutations in clinical hematology, pathology, and beyond.

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome presenting as recurrent aseptic peritonitis in a patient receiving peritoneal dialysis: a case report

BACKGROUND

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is caused by mutations in the ubiquitin-activating enzyme1 (UBA1) gene and characterised by an overlap between autoinflammatory and haematologic disorders.

CASE PRESENTATION

We reported a case of a 67-year-Japanese man receiving peritoneal dialysis (PD) who had recurrent aseptic peritonitis caused by the VEXAS syndrome. He presented with unexplained fevers, headache, abdominal pain, conjunctival hyperaemia, ocular pain, auricular pain, arthralgia, and inflammatory skin lesions. Laboratory investigations showed high serum C-reactive protein concentration and increased cell count in PD effluent. He was treated with antibiotics for PD-related peritonitis, but this was unsuccessful. Fluorine-18-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography images demonstrated intense FDG uptake in his left superficial temporal artery, nasal septum, and bilateral auricles. The working diagnosis was giant cell arteritis, and he was treated with oral prednisolone (PSL) 15 mg daily with good response. However, he was unable to taper the dose to less than 10 mg daily because his symptoms flared up. Since Tocilizumab was initiated, he could taper PSL dose to 2 mg daily. Sanger sequencing of his peripheral blood sample showed a mutation of the UBA1 gene (c.122 T > C; p.Met41Thr). We made a final diagnosis of VEXAS syndrome. He suffered from flare of VEXAS syndrome at PSL of 1 mg daily with his cloudy PD effluent. PSL dose of 11 mg daily relieved the symptom within a few days.

CONCLUSIONS

It is crucial to recognise aseptic peritonitis as one of the symptoms of VEXAS syndrome and pay attention to the systemic findings in the patients.

Knowledge and Current Practices in Monogenic Uveitis: An International Survey by IUSG and AIDA Network

INTRODUCTION

This study aims to explore awareness, knowledge, and diagnostic/therapeutic practices in monogenic uveitis (mU) among uveitis experts.

METHODS

This is an explorative, cross-sectional survey study. An anonymous, semi-structured, electronic survey was delivered to uveitis experts from the Autoinflammatory Diseases Alliance (AIDA) Network and International Uveitis Study Group (IUSG). We included respondents answering ≥ 50% of the survey.

RESULTS

Seventy-seven participants rated their knowledge of mU as proficient (3.9%), adequate (15.6%), sufficient (16.9%), or poor (63.6%). When asked about the first mU gene they thought of, 60.4% mentioned NOD2, 3.9% mentioned NLRP3 or MEFV, and 49.4% provided incorrect or no answers. Success rates in clinical scenarios varied from 15.6% to 55.8% and were higher for ophthalmologists working in multidisciplinary teams (p < 0.01). Genetic testing was ordered for suspected mU by 41.6% of physicians. The availability of molecular techniques did not significantly differ based on geography (p > 0.05). The public healthcare system ensured a higher percentage of tests prescribed were obtained by patients compared to private insurances (p < 0.00). In terms of disease-modifying anti-rheumatic drugs (DMARDs), tumor necrosis factor-α inhibitors were the most familiar to uveitis experts. The difficulties with off-label therapy procedures were the primary barrier to DMARDs prescription for patients with mU and correlated inversely with the obtained/prescribed drug ratio for interleukin-1 (p < 0.01) and interleukin-6 (p < 0.01) inhibitors.

CONCLUSIONS

This survey identifies proficiency areas, gaps, and opportunities for targeted improvements in patients care. The comprehensive outputs may inform evidence-based guidelines, empowering clinicians with standardized approaches, and drive an AIDA Network-IUSG unified effort to advance scientific knowledge and clinical practice.

VEXAS Syndrome-Diagnostic Clues for the Dermatologist and Gaps in Our Current Understanding: A Narrative Review

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome is a newly recognized, acquired autoinflammatory disorder with broad systemic implications and a poor global prognosis. Because cutaneous lesions are present in the majority of those affected, it is necessary that dermatologists are equipped to recognize this important disease. Through identification, there is a greater opportunity for disease stratification, surveillance for systemic involvement, and selection of the best available therapies. As our understanding of this disease develops, dermatologists should also play a role in addressing the knowledge gaps that exist.

VEXAS syndrome: Clinical manifestations, diagnosis, and treatment

VEXAS (Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic) syndrome is an adult-onset autoinflammatory syndrome characterized by somatic mutations in the UBA1 gene and is considered the prototype of hematoinflammatory diseases. Patients with VEXAS syndrome exhibit inflammatory and hematological manifestations that can lead to clinical diagnoses such as relapsing polychondritis, polyarteritis nodosa, Sweet syndrome, and myelodysplastic syndrome. Diagnosis requires bone marrow evaluation to identify cytoplasmic vacuoles in myeloid and erythroid precursors. However, genetic confirmation of mutations in UBA1 is necessary. Treatment is challenging and often involves glucocorticoids and immunosuppressants with variable responses. Hypomethylating agents and allogenic haemopoietic stem cell transplant are considered promising therapies. Prognosis is influenced by genetic and clinical factors. The aim of this review is to provide an overview of the pathogenesis, clinical presentation, treatment, and prognosis of VEXAS syndrome for the Latin American medical community.

[Lung involvement in autoinflammatory diseases]

Genetic autoinflammatory diseases are now a recognized and rapidly expanding group. The lung involvement historically associated with autoinflammatory diseases is inflammatory seritis, primarily seen in familial Mediterranean fever and other interleukin-1 mediated diseases. Over the last ten years, pulmonary involvement has been the core presentation of two autoinflammatory diseases associated with constitutive type I interferon activation, i.e. SAVI and COPA syndrome. Most patients with these diseases usually develop early progression to pulmonary fibrosis, which is responsible for high rates of morbidity and mortality. Other rare autoinflammatory diseases are associated with alveolar proteinosis, particularly when related to MARS mutations. Additionally, in adults, VEXAS is frequently associated with pulmonary involvement, albeit without prognosis effect. A molecular approach to autoinflammatory diseases enables not only the definition of biomarkers for diagnosis, but also the identification of targeted treatments. Examples include JAK inhibitors in SAVI and COPA syndrome, even though this therapy does not prevent progression to pulmonary fibrosis. Another illustrative example is the efficacy of methionine supplementation in alveolar proteinosis linked to MARS mutations. Overall, in autoinflammatory diseases the lung is now emerging as a possible affected organ. Continuing discovery of new autoinflammatory diseases is likely to uncover further pathologies involving the lung. Such advances are expected to lead to the development of novel therapeutic perspectives.

Clinical Manifestations in Vacuoles, E1 Enzyme, X-Linked, Autoinflammatory, Somatic (VEXAS) Syndrome: A Narrative Review

The newly identified refractory adult-onset autoinflammatory syndrome known as VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is brought on by somatic mutations in the ubiquitin-like modifier-activating enzyme 1 (UBA1) gene in hematopoietic stem and progenitor cells that change the expression of the UBA1 isoform. As a result, patients have a variety of hematologic and systemic inflammatory symptoms. All types of medical professionals should treat VEXAS syndrome seriously due to the high fatality rate. To better comprehend the condition and enhance the prognosis for VEXAS syndrome, this review article describes the essential traits and clinical signs of the condition. The discussion of future directions in the study of systemic inflammatory disorders brought on by somatic mutations concludes.

Sensitivity to targeted UBA1 inhibition in a myeloid cell line model of VEXAS syndrome

Somatic UBA1 mutations in hematopoietic cells are a hallmark of Vacuoles, E1 enzyme, X-linked, Autoinflammatory, Somatic (VEXAS) syndrome, which is a late-onset inflammatory disease associated with bone marrow failure and high mortality. The majority of UBA1 mutations in VEXAS syndrome comprise hemizygous mutations affecting methionine-41 (M41), leading to the expression of UBA1M41T, UBA1M41V, or UBA1M41L and globally reduced protein polyubiquitination. Here, we used CRISPR-Cas9 to engineer isogenic 32D mouse myeloid cell lines expressing hemizygous Uba1WT or Uba1M41L from the endogenous locus. Consistent with prior analyses of patients with VEXAS syndrome samples, hemizygous Uba1M41L expression was associated with loss of the UBA1b protein isoform, gain of the UBA1c protein isoform, reduced polyubiquitination, abnormal cytoplasmic vacuoles, and increased production of interleukin-1β and inflammatory chemokines. Vacuoles in Uba1M41L cells contained a variety of endolysosomal membranes, including small vesicles, multivesicular bodies, and multilamellar lysosomes. Uba1M41L cells were more sensitive to the UBA1 inhibitor TAK243. TAK243 treatment promoted apoptosis in Uba1M41L cells and led to preferential loss of Uba1M41L cells in competition assays with Uba1WT cells. Knock-in of a TAK243-binding mutation, Uba1A580S, conferred TAK243 resistance. In addition, overexpression of catalytically active UBA1b in Uba1M41L cells restored polyubiquitination and increased TAK243 resistance. Altogether, these data indicate that loss of UBA1b underlies a key biochemical phenotype associated with VEXAS syndrome and renders cells with reduced UBA1 activity vulnerable to targeted UBA1 inhibition. Our Uba1M41L knock-in cell line is a useful model of VEXAS syndrome that will aid in the study of disease pathogenesis and the development of effective therapies.

VEXAS-Syndrome, a newly described autoinflammatory systemic disease with dermatologic manifestations

VEXAS syndrome is a recently identified autoinflammatory systemic disease caused by an acquired somatic mutation of the X-linked UBA1 gene, the key enzyme of the first step of ubiquitylation. The acronym VEXAS stands for the characteristics Vacuoles, E1 enzyme, X-linked, autoinflammatory and somatic. The disease occurs in advanced adulthood preferentially in men and is characterized by hematological, rheumatological and dermatological symptoms. The latter include neutrophil-rich lesions reminiscent of Sweet's syndrome, erythema nodosum- and panniculitis-like skin manifestations and recurrent polychondritis of the nose and auricles. The presence of cytoplasmic vacuoles in myeloid and erythroid precursors in the bone marrow is characteristic. In up to half of the cases, VEXAS syndrome is associated with myelodysplastic syndrome. Dermatologists should be familiar with the clinical picture, as skin symptoms are often the first indicator of the disease. Molecular diagnostics are essential for confirming the diagnosis and risk stratification of affected patients. In this minireview we provide an overview of the pathophysiology, diagnosis and therapy of VEXAS syndrome and illustrate its clinical picture with two own cases.

Targeted testing of bone marrow specimens with cytoplasmic vacuolization to identify previously undiagnosed cases of VEXAS syndrome

OBJECTIVE

To retrospectively identify patients with VEXAS syndrome (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic syndrome) among male patients with bone marrow vacuolization using a clinically applicable, targeted-screening approach.

METHODS

Bone marrow reports from 1 May 2014 through 18 February 2022 were reviewed for documentation of cytoplasmic vacuolization. Patients with acute leukaemia, lymphoma, metastatic solid tumour, amyloidosis or POEMS (polyneuropathy, organomegaly, endocrinopathy, monoclonal protein, skin changes) syndrome were excluded, as were those without clinical records available for direct chart review. Cases were rated for suspicion of VEXAS syndrome using a 5-point scale based on the presence of laboratory findings, clinical features and treatment response. Patients with available DNA material and moderate (three patients) or high (four to five patients) suspicion were tested for somatic UBA1 variants associated with VEXAS syndrome.

RESULTS

A total of 315 reports from 292 unique patients included documentation of vacuolization. Following exclusion criteria, 64 patients underwent direct medical chart review to assess likelihood of VEXAS syndrome, for which 21 patients met moderate to high suspicion. Available DNA was present in eight patients, seven (87.5%) of whom had a pathogenic somatic UBA1 variant consistent with VEXAS syndrome. The distribution of cytoplasmic vacuolization in the bone marrow biopsy reports among patients with VEXAS syndrome were erythroid and myeloid precursors (6/7), erythroid precursors only (1/7) and myeloid precursors only (0/7).

CONCLUSION

In this study, the utilization of a clinically applicable targeted-screening approach to test bone marrow specimens (with vacuolization) for the presence of previously undiagnosed VEXAS syndrome resulted in a positive detection rate of 87.5%.

VEXAS-Syndrom, eine neu beschriebene autoinflammatorische Systemerkrankung mit dermatologischen Manifestationen

Das VEXAS‐Syndrom ist eine kürzlich erstbeschriebene autoinflammatorische Systemerkrankung, die auf einer erworbenen, somatischen Mutation des X‐chromosomal lokalisierten UBA1‐Gens, dem Schlüsselenzym des ersten Schritts der Ubiquitinierung, beruht. Das Akronym VEXAS steht für die Charakteristika Vacuoles, E1 enzyme, X‐linked, autoinflammatory und somatic. Die Erkrankung tritt im fortgeschrittenen Erwachsenenalter vorzugsweise bei Männern auf und ist insbesondere durch hämatologische, rheumatologische und dermatologische Symptome gekennzeichnet. Letztere umfassen unter anderem neutrophilenreiche, an das Sweet‐Syndrom erinnernde Läsionen, Erythema nodosum‐ und Pannikulitis‐artige Hauterscheinungen sowie rezidivierende Polychondritiden an Nase und Ohrmuscheln. Das Vorliegen zytoplasmatischer Vakuolen in myeloiden und erythroiden Vorläuferzellen des Knochenmarks ist charakteristisch. In bis zur Hälfte der Fälle ist das VEXAS‐Syndrom mit einem myelodysplastischen Syndrom vergesellschaftet. Dermatologen sollten das Krankheitsbild kennen, da Hauterscheinungen oft der erste Indikator für die Erkrankung sind. Eine molekulare Diagnostik ist essenziell für die Diagnosesicherung und die Risikostratifizierung betroffener Patienten. In dieser Arbeit geben wir einen Überblick über die Pathophysiologie, Diagnostik und Therapie des VEXAS‐Syndroms und illustrieren das klinische Spektrum anhand zweier eigener Fälle.

Spanish cohort of VEXAS syndrome: clinical manifestations, outcome of treatments and novel evidences about UBA1 mosaicism

BACKGROUND

The vacuoles, E1-enzyme, X linked, autoinflammatory and somatic (VEXAS) syndrome is an adult-onset autoinflammatory disease (AID) due to postzygotic UBA1 variants.

OBJECTIVES

To investigate the presence of VEXAS syndrome among patients with adult-onset undiagnosed AID. Additional studies evaluated the mosaicism distribution and the circulating cytokines.

METHODS

Gene analyses were performed by both Sanger and amplicon-based deep sequencing. Patients' data were collected from their medical charts. Cytokines were quantified by Luminex.

RESULTS

Genetic analyses of enrolled patients (n=42) identified 30 patients carrying UBA1 pathogenic variants, with frequencies compatible for postzygotic variants. All patients were male individuals who presented with a late-onset disease (mean 67.5 years; median 67.0 years) characterised by cutaneous lesions (90%), fever (66.7%), pulmonary manifestations (66.7%) and arthritis (53.3%). Macrocytic anaemia and increased erythrocyte sedimentation rate and ferritin were the most relevant analytical abnormalities. Glucocorticoids ameliorated the inflammatory manifestations, but most patients became glucocorticoid-dependent. Positive responses were obtained when targeting the haematopoietic component of the disease with either decitabine or allogeneic haematopoietic stem cell transplantation. Additional analyses detected the UBA1 variants in both haematopoietic and non-haematopoietic tissues. Finally, analysis of circulating cytokines did not identify inflammatory mediators of the disease.

CONCLUSION

Thirty patients with adult-onset AID were definitively diagnosed with VEXAS syndrome through genetic analyses. Despite minor interindividual differences, their main characteristics were in concordance with previous reports. We detected for the first time the UBA1 mosaicism in non-haematopoietic tissue, which questions the previous concept of myeloid-restricted mosaicism and may have conceptual consequences for the disease mechanisms.

[Scleritis and episcleritis]

Scleritis and episcleritis are rare ocular inflammatory diseases but deserve to be known by internists because of their frequent association with systemic autoimmune diseases. It is important to distinguish them between because their prognosis, therapeutic management and potential complications are very different. Episcleritis represents a superficial ocular inflammation with usually benign visual prognosis, no complication with local treatment, and is associated with a systemic autoimmune disease in rare cases. In contrast, scleritis is a potentially serious ophthalmological condition that can threaten the visual prognosis in the absence of appropriate systemic treatment. It is associated with an underlying disease in 40-50% of cases, in particular a systemic autoimmune disease (25-35% of cases) or an infectious cause (5-10% of cases). Rheumatoid arthritis and systemic vasculitides, particularly antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides, are the main autoimmune causes of scleritis and episcleritis. Scleritis can reveal the underlying autoimmune disease and requires systematic etiological investigations. Aggressive, complicated, refractory forms or those associated with a systemic autoimmune disease require glucocorticoids or even immunosuppressants, and close collaboration between ophthalmologists and internists is required. The development of biologic agents offers new effective therapeutic tools in the management of these difficult cases.

Premalignant Clonal Hematopoiesis (Clonal Hematopoiesis of Indeterminate Potential and Clonal Cytopenia of Undetermined Significance)

Premalignant clonal hematopoiesis is the presence of somatic alterations in the blood of otherwise healthy individuals. Although the condition is not considered as a cancer, it carries an increased risk of developing a hematologic malignancy, particularly in those with large neoplastic clones, multiple pathogenic mutations, and high-risk mutations. In addition to the increased risk of malignancy, clonal hematopoiesis carries a markedly increased risk of cardiovascular events and death. Appropriate identification of this entity is critical to mitigate cardiovascular risk factors and ensure appropriate monitoring for the emergence of blood cancer.

Polyarteritis Nodosa: Old Disease, New Etiologies

Polyarteritis nodosa (PAN), also known as panarteritis nodosa, represents a form of necrotizing vasculitis that predominantly affects medium-sized vessels, although it is not restricted to them and can also involve smaller vessels. The clinical presentation is heterogeneous and characterized by a significant number of patients exhibiting general symptoms, including asthenia, fever, and unintended weight loss. Although PAN can involve virtually any organ, it preferentially affects the skin, nervous system, and the gastrointestinal tract. Orchitis is a rare but specific manifestation of PAN. The absence of granulomas, glomerulonephritis, and anti-neutrophil cytoplasmic antibodies serves to distinguish PAN from other types of vasculitis. Major complications consist of hemorrhagic and thrombotic events occurring in mesenteric, cardiac, cerebral, and renal systems. Historically, PAN was frequently linked to hepatitis B virus (HBV) infection, but this association has dramatically changed in recent years due to declining HBV prevalence. Current epidemiological research often identifies a connection between PAN and genetic syndromes as well as neoplasia. This article provides a comprehensive review of PAN, specifically focusing on the progression of its clinical manifestations over time.

How to treat VEXAS syndrome: a systematic review on effectiveness and safety of current treatment strategies

OBJECTIVES

To evaluate the effectiveness and safety of current treatment strategies for the vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome.

METHODS

A protocolized systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines was performed. Three databases were searched for reports on treatment strategies for VEXAS. Data from the included publications was extracted and a narrative synthesis was performed. Treatment response was recorded as complete (CR), partial (PR) or none (NR) depending on changes in clinical symptoms and laboratory parameters. Patient characteristics, safety data and previous treatments were analysed.

RESULTS

We identified 36 publications with a total of 116 patients; 113 (98.3%) were male. The identified reports included azacytidine (CR 9/36, 25%; PR 14/36, 38.9%), Janus kinase inhibitors (JAKi) (CR 11/33, 33%; PR 9/33, 27.3%), tocilizumab (CR 3/15, 20%; PR 6/15, 40%), allogeneic stem cell transplantation (CR 6/7, 85.7%; one patient died), anakinra (CR 4/5, 80%; NR 1/5, 20%), canakinumab (CR 1/2, 50%; PR 1/2, 50%) and glucocorticoid monotherapy (CR 1/6, 16.7%; PR 4/6, 66.7%). Individual reports were available for TNF inhibitors, rituximab and MTX. Data on adverse events were available for 67 patients (67/116, 57.8%) and included: pneumonia (12/67, 17.9%), other infections (9/67, 13.4%), venous thromboembolisms (6/67, 8.9%), cytopenias (4/67, 5.9%), and acute (4/67, 5.9%) and chronic graft-vs-host-disease (2/67, 2.9%).

CONCLUSION

Current data on VEXAS treatment are limited and inhomogeneous. Treatment decisions should be individualized. For the devolvement of treatment algorithms clinical trials are needed. Adverse events remain a challenge, especially an elevated risk for venous thromboembolism associated to JAKi treatment should be carefully considered.

[Dysimmune manifestations associated with myelodysplastic neoplasms and chronic myelomonocytic leukaemias]

Systemic inflammatory or autoimmune diseases (SIAD) are observed in up to a quarter of patients with myelodysplastic syndromes (MDS) or chronic myelomonocytic leukemia (CMML), with a broad clinical spectrum including asymptomatic biological abnormalities, isolated inflammatory clinical manifestations (recurrent fever, arthralgia, neutrophilic dermatoses…) or identified systemic diseases (giant cell arteritis, recurrent polychondritis…). Recent advances in molecular biology have shed new light on the pathophysiological mechanisms that link inflammatory manifestations and myeloid hemopathies, particularly in VEXAS syndrome following the identification of somatic mutations in the UBA1 gene, or in neutrophilic dermatoses with the concept of myelodysplasia cutis. Although the presence of SIAD does not seem to affect overall survival or the risk of transformation into acute myeloid leukemia, their treatment remains a challenge given the frequent high level of corticosteroid dependence as well as the poor efficacy and tolerance (cytopenias, infections) of conventional immunosuppressive agents. Recent prospective data supports the interest of a therapeutic strategy using demethylating agents and notably azacitidine to target the pathological clone.

Predictive Clinical and Biological Criteria for Gene Panel Positivity in Suspected Inherited Autoinflammatory Diseases: Insights from a Case-Control Study

In order to assess the clinical and biological criteria that predict gene panel positivity in patients with a suspected inherited genetic autoinflammatory disease, we conducted a case-control study. These new selection criteria could replace the national multidisciplinary staff approval before performing genetic testing that has been required since 2019. The study involved 119 positive gene panels matched by panel sizes to 119 randomly selected negative gene panels. The patients were referred to our laboratory for genetic testing between June 2012, and March 2023. The clinical and biological criteria were extracted from a prospectively filled database. We focused our evaluation on accuracy and the positive predictive value. Neonatal symptom onset and deafness had the highest accuracies among all criteria associated with the positivity panel, with 92.9% (88.6; 96.0) and 92.6% (88.5; 95.6), respectively. However, it is important to note that the associated Positive Predictive Values (PPVs) cannot exceed 50%. Despite finding a statistical association between clinical and biological criteria and panel positivity, the predictive values of these criteria were not sufficient to recommend Next-Generation Sequencing (NGS) gene panel testing without the national multidisciplinary staff evaluation.

Shared and Distinct Mechanisms of UBA1 Inactivation Across Different Diseases

Most cellular ubiquitin signaling is initiated by UBA1, which activates and transfers ubiquitin to tens of E2 enzymes. Clonally acquired UBA1 missense mutations cause an inflammatory-hematologic overlap disease called VEXAS (vacuoles, E1, X-linked, autoinflammatory, somatic) syndrome. Despite extensive clinical investigation into this lethal disease, little is known about the underlying molecular mechanisms. Here, by dissecting VEXAS-causing UBA1 mutations, we discovered that p.Met41 mutations alter cytoplasmic isoform expression, whereas other mutations reduce catalytic activity of nuclear and cytoplasmic isoforms by diverse mechanisms, including aberrant oxyester formation. Strikingly, non-p.Met41 mutations most prominently affect transthioesterification, revealing ubiquitin transfer to cytoplasmic E2 enzymes as a shared property of pathogenesis amongst different VEXAS syndrome genotypes. A similar E2 charging bottleneck exists in some lung cancer-associated UBA1 mutations, but not in spinal muscular atrophy-causing UBA1 mutations, which instead, render UBA1 thermolabile. Collectively, our results highlight the precision of conformational changes required for faithful ubiquitin transfer, define distinct and shared mechanisms of UBA1 inactivation in diverse diseases, and suggest that specific E1-E2 modules control different aspects of tissue differentiation and maintenance.

Clinical and genetic features of Japanese cases of MDS associated with VEXAS syndrome

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a new disease entity with autoinflammatory disorders (AID) driven by somatic variants in UBA1 that frequently co-exists with myelodysplastic syndromes (MDS). Clinicopathological and molecular features of Japanese cases with VEXAS-associated MDS remain elusive. We previously reported high prevalence of UBA1 variants in Japanese patients with relapsing polychondritis, in which 5 cases co-occurred with MDS. Here, we report clinicopathological and variant profiles of these 5 cases and 2 additional cases of MDS associated with VEXAS syndrome. Clinical characteristics of these cases included high prevalence of macrocytic anemia with marked cytoplasmic vacuoles in myeloid/erythroid precursors and low bone marrow (BM) blast percentages. All cases were classified as low or very low risk by the revised international prognostic scoring system (IPSS-R). Notably, 4 out of 7 cases showed significant improvement of anemia by treatment with prednisolone (PSL) or cyclosporin A (CsA), suggesting that an underlying inflammatory milieu induced by VEXAS syndrome may aggravate macrocytic anemia in VEXAS-associated MDS. Targeted deep sequencing of blood samples suggested that MDS associated with VEXAS syndrome tends to involve a smaller number of genes and lower risk genetic lesions than classical MDS.

[Autoinflammatory syndromes]

The concept of autoinflammation includes a heterogeneous group of monogenic and polygenic diseases. These are characterized by excessive activation of the innate immune system without antigen-specific T cells or autoantibodies. The diseases are characterized by periodic episodes of fever and increased inflammation parameters. Monogenic diseases include familial Mediterranean fever (FMF) and the newly described VEXAS (vacuoles, E1 enzyme, X‑linked, autoinflammatory, somatic) syndrome. Heterogeneous diseases include adult-onset Still's disease and Schnitzler syndrome. Treatment is aimed at preventing the excessive inflammatory reaction in order to avoid long-term damage, such as amyloid A (AA) amyloidosis.

Episcleritis and periorbital edema secondary to VEXAS syndrome

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a newly described autoinflammatory entity caused by a UBA-1 gene mutation. Among the most frequent symptoms it produces fever, cytopenias, polychondritis, pulmonary infiltrates and up to 40% ocular involvement such as periorbital edema, uveitis, episcleritis, scleritis and retinal vasculitis. Patients respond to high doses of corticosteroids, however, many end up being refractory to them and to the classic immunosuppressants. We described the case of a 77-year-old male patient with ocular involvement in the form of episcleritis and periorbital edema who was later diagnosed with VEXAS Syndrome. The patient, after failing treatment with immunosuppressants, is currently receiving treatment with oral steroids and tocilizumab. Ophthalmologist must be aware of the ophthalmological affectation of autoinflammatory diseases and especially of this new entity described as the VEXAS Syndrome.

C-Reactive Protein: Pathophysiology, Diagnosis, False Test Results and a Novel Diagnostic Algorithm for Clinicians

The current literature provides a body of evidence on C-Reactive Protein (CRP) and its potential role in inflammation. However, most pieces of evidence are sparse and controversial. This critical state-of-the-art monography provides all the crucial data on the potential biochemical properties of the protein, along with further evidence on its potential pathobiology, both for its pentameric and monomeric forms, including information for its ligands as well as the possible function of autoantibodies against the protein. Furthermore, the current evidence on its potential utility as a biomarker of various diseases is presented, of all cardiovascular, respiratory, hepatobiliary, gastrointestinal, pancreatic, renal, gynecological, andrological, dental, oral, otorhinolaryngological, ophthalmological, dermatological, musculoskeletal, neurological, mental, splenic, thyroid conditions, as well as infections, autoimmune-supposed conditions and neoplasms, including other possible factors that have been linked with elevated concentrations of that protein. Moreover, data on molecular diagnostics on CRP are discussed, and possible etiologies of false test results are highlighted. Additionally, this review evaluates all current pieces of evidence on CRP and systemic inflammation, and highlights future goals. Finally, a novel diagnostic algorithm to carefully assess the CRP level for a precise diagnosis of a medical condition is illustrated.

Recurrent superior orbital fissure syndrome associated with VEXAS syndrome

PURPOSE

To describe a case of recurrent orbital inflammation and superior orbital fissure syndrome associated with VEXAS (vacuoles, E1 enzyme, X-linked, auto-inflammatory, somatic) syndrome.

CASE PRESENTATION

VEXAS syndrome is a recently identified multi-system inflammatory disease of late adult onset. The authors describe the case of a 76-year-old man who presented with recurrent episodes of orbital inflammation, with superior orbital fissure syndrome, dacryoadenitis and orbital myositis. He had a constellation of systemic disorders including recurrent chest infections, congestive cardiac failure, pulmonary emboli and skin rashes. The underlying diagnosis of VEXAS syndrome was confirmed by genetic testing, which revealed the UBA1 mutation.

CONCLUSION

VEXAS syndrome should be considered in the differential diagnosis of orbital inflammatory disease associated with multi-system inflammatory disorders.

VEXAS Syndrome-Review

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a newly defined refractory adult-onset autoinflammatory syndrome caused by somatic mutations in the ubiquitin-like modifier-activating enzyme 1 (UBA1) gene in hematopoietic stem and progenitor cells, resulting in a shift in UBA1 isoform expression. Thus, patients develop a spectrum of systemic inflammatory manifestations and hematologic symptoms. To date, patients respond poorly to immune suppressive drugs, except high-dose glucocorticoids, and no treatment guidelines have been established. Given the high mortality rate, VEXAS syndrome needs to be taken seriously by physicians in all specialties. This article aims to describe the key features, pathogenesis, and clinical manifestations of VEXAS syndrome to better understand the targeted treatment and improve the prognosis of VEXAS syndrome.

VEXAS Syndrome-A Review of Pathophysiology, Presentation, and Prognosis

ABSTRACT

VEXAS ( V acuoles, E 1 enzyme, X -linked, A utoinflammatory, S omatic) syndrome is a newly identified disease caused by somatic mutations in the UBA1 gene resulting in refractory autoinflammatory features, frequently accompanied by cytopenias. Although the prevalence of this syndrome is yet unknown, understanding the clinical phenotype can assist clinicians in prompt recognition of cases among patients with glucocorticoid-responsive but immunosuppressive-resistant inflammatory symptoms. The pathophysiology, clinical presentation, diagnostic methods, treatment, and prognosis of VEXAS are herein reviewed.

Early activation of inflammatory pathways in UBA1-mutated hematopoietic stem and progenitor cells in VEXAS

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is a pleiotropic, severe autoinflammatory disease caused by somatic mutations in the ubiquitin-like modifier activating enzyme 1 (UBA1) gene. To elucidate VEXAS pathophysiology, we performed transcriptome sequencing of single bone marrow mononuclear cells and hematopoietic stem and progenitor cells (HSPCs) from VEXAS patients. HSPCs are biased toward myeloid (granulocytic) differentiation, and against lymphoid differentiation in VEXAS. Activation of multiple inflammatory pathways (interferons and tumor necrosis factor alpha) occurs ontogenically early in primitive hematopoietic cells and particularly in the myeloid lineage in VEXAS, and inflammation is prominent in UBA1-mutated cells. Dysregulation in protein degradation likely leads to higher stress response in VEXAS HSPCs, which positively correlates with inflammation. TCR usage is restricted and there are increased cytotoxicity and IFN-γ signaling in T cells. In VEXAS syndrome, both aberrant inflammation and myeloid predominance appear intrinsic to hematopoietic stem cells mutated in UBA1.

VEXAS syndrome: a diagnostic puzzle

The VEXAS syndrome (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) is an adult-onset systemic autoinflammatory condition that is caused by an acquired deficiency of the UBA1 gene in hematopoietic progenitor cells. The clinical spectrum of the VEXAS syndrome currently comprises a broad range of phenotypes such as vasculitis, relapsing polychondritis and Sweet's syndrome. In the past, VEXAS patients have left clinicians puzzled and the true nature of this disease has not been captured until late 2020. This viewpoint describes the relevant clinical features of the VEXAS syndrome and reviews different approaches to establish the diagnosis. Finally, future directions within the field of systemic inflammatory diseases caused by somatic mutations are being discussed.

VEXAS syndrome: Current clinical, diagnostic and treatment approaches

VEXAS syndrome, is a hemato-inflammatory chronic disease characterized with predominantly rheumatic and hematologic systemic involvement. It was first described in 2020 by a group of researchers in the United States. VEXAS syndrome is a rare condition that primarily affects adult males and is caused by a mutation in the UBA1 gene located on the X chromosome. Its pathogenesis is related to the somatic mutation affecting methionine-41 (p.Met41) in UBA1, the major E1 enzyme that initiates ubiquitylation. Mutant gene lead to decreased ubiquitination and activated innate immune pathways and systemic inflammation occur. The specific mechanism by which the UBA1 mutation leads to the clinical features of VEXAS syndrome is not yet fully understood. VEXAS is a newly define adult-onset inflammatory syndrome manifested with treatment-refractory fevers, arthritis, chondritis, vasculitis, cytopenias, typical vacuoles in hematopetic precursor cells, neutrophilic cutaneous and pulmonary inflammation. Diagnosing VEXAS syndrome can be challenging due to its rarity and the overlap of symptoms with other inflammatory conditions. Genetic testing to identify the UBA1 gene mutation is essential for definitive diagnosis. Currently, there is no known cure for VEXAS syndrome, and treatment mainly focuses on managing the symptoms. This may involve the use of anti-inflammatory medications, immunosuppressive drugs, and supportive therapies tailored to the individual patient's needs. Due to the recent discovery of VEXAS syndrome, ongoing research is being conducted to better understand its pathogenesis, clinical features, and potential treatment options. In this review article, the clinical, diagnostic and treatment approaches of VEXAS syndrome were evaluated in the light of the latest literature data.

Correlation analysis between auto-immunological and mutational profiles in myelodysplastic syndromes

OBJECTIVE AND DESIGN

Systemic-Inflammatory-Autoimmune-Diseases (SIAD) is increasingly considered in Myelodysplastic-Syndromes (MDS). In this line, we evaluated the MDS auto-immunological profile, correlating it to the mutational landscape, trying to identify a molecular-genetic trigger agent related to SIAD.

METHODS AND MATERIALS

Eighty-one MDS were enrolled and t-NGS was performed. Anti-Nuclear-Antibodies (ANA) were tested, and ANA-antigenic-specificity was characterized by ANA-profile, ENA-screen, anti-dsDNA. Non-Hematological-Patients (NHP) and Healthy-Donors (HD) were used as controls.

RESULTS

At clinically relevant cut-off (≥ 1:160), ANA was significantly more frequent in MDS, while ANA-antigenic-specificity showed a low association rate. ANA ≥ 1:160-positive MDS showed a mutational landscape similar to ANA-negative/ANA < 1:160 MDS. No significant correlations between mutational and immunological profiles were found and UBA1 mutations, related to VEXAS, were absent.

CONCLUSIONS

Although ANA-positivity was found to be increased in MDS, the low ANA-antigenic-specificity suggests that autoantibodies didn't recognize autoimmune-pathognomonic antigens. The lack of relationship between genetic profile and ANA-positivity, suggests that MDS genetic variants may not be the direct cause of SIAD.

Vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome in the intensive care unit: a case report

BACKGROUND

Vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome is a newly discovered inflammatory disease affecting male subjects, for which few data exist in the literature. Here, we describe the case of a patient with known Sweet's syndrome admitted to the intensive care unit and for whom a vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome was diagnosed, allowing for appropriate treatment and the patient's discharge and recovery.

CASE PRESENTATION

A 70-year-old male White patient was hospitalized in the intensive care unit following an intrahospital cardiac arrest. History started a year before with repeated deep vein thrombosis and episodes of skin eruption compatible with Sweet's syndrome. After a course of oral steroids, fever and inflammatory syndrome relapsed with onset of polychondritis, episcleritis along with neurological symptoms and pulmonary infiltrates. Intrahospital hypoxic cardiac arrest happened during patient's new investigations, and he was admitted in a critical state. During the intensive care unit stay, he presented with livedoid skin lesions on both feet. Vasculitis was not proven; however, cryoglobulinemia screening came back positive. Onset of pancytopenia was explored with a myelogram aspirate. It showed signs of dysmyelopoiesis and vacuoles in erythroid and myeloid precursors. Of note, new deep vein thrombosis developed, despite being treated with heparin leading to the diagnosis of heparin-induced thrombocytopenia. The course of symptoms were overlapping multiple entities, and so a multidisciplinary team discussion was implemented. Screening for UBA1-mutation in the blood came back positive, confirming the vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome. Corticosteroids and anti-IL1 infusion were started with satisfactory results supporting patient's discharge from intensive care unit to the internal medicine ward.

CONCLUSIONS

Vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome should be suspected in male patients presenting with inflammatory symptoms, such as fever, skin eruption, chondritis, venous thromboembolism, and vacuoles in bone marrow precursors. Patients with undiagnosed vacuoles, E1 enzyme, X-linked, autoinflammatory, and somatic syndrome may present with organ failure requiring hospitalization in intensive care unit, where screening for UBA1 mutation should be performed when medical history is evocative. Multidisciplinary team involvement is highly recommended for patient management, notably to start appropriate immunosuppressive treatments.

Novel Somatic UBA1 Variant in a Patient With VEXAS Syndrome

OBJECTIVE

Somatic mutations in UBA1 have recently been causally linked to a severe adult-onset inflammatory condition referred to as VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome. Ubiquitin-activating enzyme E1 (UBA-1) is of fundamental importance to the modulation of ubiquitin homeostasis and to the majority of downstream ubiquitylation-dependent cellular processes. Direct sequencing analysis of exon 3 containing the prevalent variants p.Met41Leu, p.Met41Val, and/or p.Met41Thr is usually used to confirm the disease-associated mutations.

METHODS

We studied the clinical, biochemical, and molecular genetic characteristics of a 59-year-old man with a 2-year history of arthritis, fever, night sweats, nonspecific skin rash, lymphadenopathy, and myelodysplastic syndrome with multilineage dysplasia.

RESULTS

The mutational analysis revealed a previously undescribed sequence variant c.1430G>C in exon 14 (p.Gly477Ala) in the gene UBA1. In vitro enzymatic analyses showed that p.Gly477Ala led to both decreased E1 ubiquitin thioester formation and E2 enzyme charging.

CONCLUSION

We report a case of a patient of European ancestry with clinical manifestations of VEXAS syndrome associated with a newly identified dysfunctional UBA-1 enzyme variant. Due to the patient's insufficient response to various immunosuppressive treatments, allogeneic hematopoietic stem cell transplantation was performed, which resulted in significant improvement of clinical and laboratory manifestations of the disease.

Accurate stratification between VEXAS syndrome and differential diagnoses by deep learning analysis of peripheral blood smears

OBJECTIVES

VEXAS syndrome is a newly described autoinflammatory disease associated with UBA1 somatic mutations and vacuolization of myeloid precursors. This disease possesses an increasingly broad spectrum, leading to an increase in the number of suspected cases. Its diagnosis via bone-marrow aspiration and UBA1-gene sequencing is time-consuming and expensive. This study aimed at analyzing peripheral leukocytes using deep learning approaches to predict VEXAS syndrome in comparison to differential diagnoses.

METHODS

We compared leukocyte images from blood smears of three groups: participants with VEXAS syndrome (identified UBA1 mutation) (VEXAS); participants with features strongly suggestive of VEXAS syndrome but without UBA1 mutation (UBA1-WT); participants with a myelodysplastic syndrome and without clinical suspicion of VEXAS syndrome (MDS). To compare images of circulating leukocytes, we applied a two-step procedure. First, we used self-supervised contrastive learning to train convolutional neural networks to translate leukocyte images into lower-dimensional encodings. Then, we employed support vector machine to predict patients' condition based on those leukocyte encodings.

RESULTS

The VEXAS, UBA1-WT, and MDS groups included 3, 3, and 6 patients respectively. Analysis of 33,757 images of neutrophils and monocytes enabled us to distinguish VEXAS patients from both UBA1-WT and MDS patients, with mean ROC-AUCs ranging from 0.87 to 0.95.

CONCLUSIONS

Image analysis of blood smears via deep learning accurately distinguished neutrophils and monocytes drawn from patients with VEXAS syndrome from those of patients with similar clinical and/or biological features but without UBA1 mutation. Our findings offer a promising pathway to better screening for this disease.

Pulmonary manifestations in VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome: a systematic review

BACKGROUND

VEXAS (vacuoles, E1 enzyme, X-linked, auto-inflammatory, somatic) syndrome is a newly described auto-inflammatory disease. Many cases feature pulmonary infiltrates or respiratory failure. This systematic review aimed to summarize respiratory manifestations in VEXAS syndrome described to date.

METHODS

Databases were searched for articles discussing VEXAS syndrome until May 2022. The research question was: What are the pulmonary manifestations in patients with VEXAS syndrome? The search was restricted to English language and those discussing clinical presentation of disease. Information on basic demographics, type and prevalence of pulmonary manifestations, co-existing disease associations and author conclusions on pulmonary involvement were extracted. The protocol was registered on the PROSPERO register of systematic reviews.

RESULTS

Initially, 219 articles were retrieved with 36 ultimately included (all case reports or series). A total of 269 patients with VEXAS were included, 98.6% male, mean age 66.8 years at disease onset. The most frequently described pulmonary manifestation was infiltrates (43.1%; n = 116), followed by pleural effusion (7.4%; n = 20) and idiopathic interstitial pneumonia (3.3%; n = 9). Other pulmonary manifestations were: nonspecific interstitial pneumonia (n = 1), bronchiolitis obliterans (n = 3), pulmonary vasculitis (n = 6), bronchiectasis (n = 1), alveolar haemorrhage (n = 1), pulmonary embolism (n = 4), bronchial stenosis (n = 1), and alveolitis (n = 1). Several patients had one or more co-existing autoimmune/inflammatory condition. It was not reported which patients had particular pulmonary manifestations.

CONCLUSION

This is the first systematic review undertaken in VEXAS patients. Our results demonstrate that pulmonary involvement is common in this patient group. It is unclear if respiratory manifestations are part of the primary disease or a co-existing condition. Larger epidemiological analyses will aid further characterisation of pulmonary involvement and disease management.

Successful azacitidine therapy for myelodysplastic syndrome associated with VEXAS syndrome

VEXAS (vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic) syndrome is caused by UBA1 somatic mutations and is characterized by late-onset systemic autoimmune inflammation and blood abnormalities such as cytopenia, vacuolation of myeloid/erythroblastic cells, and myelodysplastic syndrome (MDS). It is often resistant to immunosuppressive therapy, and no treatment strategy has been established. A 65-year-old man presented with palpable erythema, fever, macrocytic anemia, and arthralgia. He was subsequently diagnosed with MDS complicated by Sweet's disease. Treatment with azacitidine was initiated due to suspected skin invasion by MDS cells and resistance of the skin rash to steroid therapy. Next-generation sequencing of bone marrow samples prior to treatment initiation revealed the presence of UBA1 p.M41L (VAF 0.38) and DNMT3A p.L605fs mutations (VAF 0.184). Based on the findings of systemic inflammation, a diagnosis of VEXAS syndrome was made. The fever and skin rash improved with azacitidine therapy. In conclusion, somatic mutations in UBA1 should be explored in patients with MDS exhibiting systemic autoimmune inflammation. Furthermore, azacitidine may be a good treatment option for systemic autoinflammation in MDS associated with VEXAS syndrome.

VEXAS syndrome: a newly discovered systemic rheumatic disorder

VEXAS syndrome is an adult-onset autoinflammatory disease associated with hematologic symptoms. The disease affects primarily males, and leads to death of a significant proportion of the patients. VEXAS syndrome is caused by a somatic mutation of the UBA1 gene in hematopoietic progenitor cells. The clinical picture of the syndrome consists of a number of organ manifestations including those akin to rheumatic diseases, arthritis, myalgia, vasculitis and chondritis.

A 79-Year-Old Man With Recurrent Respiratory and Constitutional Symptoms, Elevated Acute Phase Reactants, and Pancytopenia

CASE PRESENTATION

A 79-year-old man was examined because of recurrent dyspnea and constitutional symptoms that included malaise, fatigue, fevers, and arthralgias over the past 7 years. He was a nonsmoker who was a retired farmer. Elevated levels of acute phase reactants and C-reactive protein and a high erythrocyte sedimentation rate were noted often in his health records. However, an extensive rheumatologic evaluation, which included serologic studies (antinuclear antibodies, cyclic citrullinated peptide antibodies, antineutrophil cytoplasmic antibodies) and temporal artery biopsy, had not shown an identifiable autoimmune disease. The patient had been treated intermittently with prednisone, with partial symptomatic improvement. Various cytopenias had been present over the preceding years; however, three bone marrow biopsy specimens showed moderately hypercellular bone marrow with no diagnostic findings.

JAK inhibitors for the treatment of VEXAS syndrome

Vacuoles, E1 enzyme, X-linked, autoinflammatory, somatic (VEXAS) syndrome is a novel described autoinflammatory entity for which the diagnosis is defined by somatic mutations of the UBA1 X-linked gene in hematopoietic progenitor cells. The clinical manifestations are heterogeneous since they range from autoinflammatory symptoms to the presence of underlying hematologic disorders such as myelodysplastic syndromes. Response to treatment in VEXAS is very poor and to date, the therapeutic strategies adopted are only partially effective. However, recently described cohorts of subjects with VEXAS treated with Janus kinase inhibitors (JAK-I) proved that these drugs can be effective in the treatment of several manifestations related to the disease. Herein, we carried out a brief literature review that includes cohorts and single cases in which JAK-I were adopted as a promising strategy to manage VEXAS patients. Subsequently, we described our experience with JAK-I in VEXAS, illustrating the first case, to our knowledge, of a 65-year-old man who was successfully treated with the selective JAK-1 inhibitor filgotinib.

[Autoinflammatory syndromes]

The concept of autoinflammation includes a heterogeneous group of monogenic and polygenic diseases. These are characterized by excessive activation of the innate immune system without antigen-specific T cells or autoantibodies. The diseases are characterized by periodic episodes of fever and increased inflammation parameters. Monogenic diseases include familial Mediterranean fever (FMF) and the newly described VEXAS (vacuoles, E1 enzyme, X‑linked, autoinflammatory, somatic) syndrome. Heterogeneous diseases include adult-onset Still's disease and Schnitzler syndrome. Treatment is aimed at preventing the excessive inflammatory reaction in order to avoid long-term damage, such as amyloid A (AA) amyloidosis.

VEXAS Syndrome: A Call for Diagnostic Awareness Based on a Case Series of Seven Patients

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Clonal Hematopoiesis: Origins and determinants of evolution

The accrual of somatic mutations is a byproduct of aging. When a clone bearing a somatic genetic alteration, conferring comparative competitive advantage, displays sufficient outgrowth to become detectable amongst an otherwise polyclonal background in the hematopoietic system, this is called clonal hematopoiesis (CH). Somatic genetic alterations observed in CH include point mutations in cancer related genes, mosaic chromosomal alterations or a combination of these. Interestingly, clonal hematopoiesis (CH) can also occur with somatic variants in genes without a known role in cancer and in the absence of a somatic genetic alteration through a process that has been described as 'genetic drift'. Clonal hematopoiesis of indeterminate significance (CHIP), is age-related and defined by the presence of somatic point mutations in cancer related genes, in the absence of cytopenias or a diagnosis of hematologic neoplasm, with a variant allele fraction ≥ 2 %. Remarkably, the increased mortality associated with CHIP is largely due to cardiovascular disease. Subsequently, CHIP has been associated with a myriad of age-related conditions such as Alzheimer's Disease, osteoporosis, CVA and COPD. CHIP is associated with an increased risk of hematologic malignancies, particularly myeloid neoplasms, with the risk rising with increasing clone size and clonal complexity. Mechanisms regulating clonal evolution and progression to hematologic malignancies remain to be defined. However, observations on context specific CH arising in the setting of bone marrow failure states, or on exposure to chemotherapy and radiation therapy, suggest that CH reflects context specific selection pressures and constraint-escape mechanisms.