Essential Thrombocythemia Research Articles

Current myeloproliferative neoplasm scoring systems for clinical practice.

BCR::ABL1-negative myeloproliferative neoplasms (MPN) are clonal hematological malignancies resulting from the proliferation of myeloid cells harboring a JAK-STAT pathway activating driver mutation. MPN management recommendations are based on the evaluation of different risks to prevent disease evolution associated events while preserving patients' quality of life. Such risks can be common across all MPN or specific to each subtype (polycythemia vera (PV), essential thrombocythemia (ET), prefibrotic myelofibrosis (pre-MF), primary myelofibrosis (PMF)). MF-patients harbor the worse prognosis and hematopoietic stem cell transplantation (HSCT) is the only curative treatment, at the expense of a high morbi-mortality. Therefore, accurate scoring systems to estimate overall survival are crucial for MF patients' management and selection for HSCT. In PV and ET, vascular events prediction is prioritized given their higher incidence and related morbi-mortality. Finally, quality of life evaluation is important for all subtypes. To predict these risks and adapt MPN therapeutic strategies, clinical risk scores have been developed over the past decades, more recently including molecular risk factors for more accurate risk stratification. The large number of scoring systems available in combination with disease heterogeneity and the necessity to predict diverse outcomes, make it difficult for clinicians to choose the most appropriate score to evaluate their patients' risk in 2024. Here, we provide an overview of MPN disease evolution associated events incidence and conduct an exhaustive comparative review of the scoring systems currently available for each risk. Finally, we propose an algorithm for the use of these scores in clinical practice in each MPN subtype.

Myeloproliferative Neoplasm-like Mutations of Calreticulin Induce Phenotypes Associated with Calreticulin Dysfunction in C. elegans

In previous research, we created a C. elegans model with homozygous mutations in calreticulin similar to those found in patients with essential thrombocythemia (ET) and primary myelofibrosis (PMF), two myeloproliferative neoplasms (MPNs). This model, lacking JAK orthologs, enabled us to examine the transcriptomic effects caused by mutant calreticulin without the influence of JAK/STAT activation, the primary pathogenic mechanism associated with calreticulin mutations known to date. Most of the gene expression changes observed seemed to be due to a partial loss of protein function, with the alteration of the extracellular matrix being particularly notable. In this study, our aim was to determine whether this model exhibited any phenotype related to these transcriptomic alterations. The results demonstrate that these strains exhibit multiple phenotypes related to the alteration of the extracellular matrix, fat levels, and fertility, which could be a possible consequence of a partial loss of calreticulin function. These phenotypes resemble some of the clinical and molecular characteristics described in patients with MPNs, but they had never before been linked to a loss of protein function in humans. Thus, these results collectively suggest that CALR mutations could have significant effects on MPNs due to loss of protein function. Delving deeper into these effects to develop innovative therapies for these patients offers considerable potential and interest, given that targeted therapies for these patients have not yielded very promising results so far.

Single-cell mass cytometry analysis unveils prothrombotic expression and heterogeneity in essential thrombocythemia

Abstract Background/Introduction Essential thrombocythemia (ET) is recognized for its hallmark elevated platelet count and a consequent increased risk of thromboembolic events including coronary events. Despite its clinical significance, the pathophysiological mechanisms predisposing ET patients to thrombosis remain largely undefined. Purpose The aim of this pioneering study was to shed light on the increased thrombotic risk in ET by conducting a detailed phenotypical characterization of platelet expression using single-cell mass cytometry, comparing ET patients to age- and sex-matched healthy controls. Methods Platelet samples from six patients diagnosed with ET and six healthy individuals were analyzed. This analysis utilized an extensive panel of 18 transmembrane regulators pivotal for platelet function and activation. Measurements were taken both at baseline and after ex-vivo stimulation with thrombin receptor-activating peptide (TRAP). Advanced clustering analysis via the FlowSOM algorithm helped identify specific subclusters of platelets with a prothrombotic expression profile. Results Our investigation revealed a significant overexpression of the activation marker CD62P (P-Selectin, p=0.049) and of the collagen receptor GPVI (p=0.044) in non-stimulated ET platelets (Figure 1A-C). Conversely, a notable decrease in expression was observed for the fibrinogen receptor GPIIb/IIIa units CD41 (p=0.036) and CD61 (p=0.044), as well as for the von Willebrand factor receptor CD42b (p=0.044). The FlowSOM analysis distinguished two prothrombotic subclusters of ET platelets, particularly highlighting one cluster, which was significantly overrepresented in ET (22.13% of total ET platelets versus 2.94% in controls, p=0.035, Figure 1D-E). Conclusion This study presents compelling evidence of a distinct prothrombotic phenotype in ET, marked by significant alterations in platelet expression profiles. The overexpression of CD62P and GPVI, alongside the underexpression of CD41, CD61, and CD42b, underscores the complex pathophysiological landscape of ET. Importantly, we identified a specific subcluster, particularly overrepresented in ET, with a specific prothrombic signature. Our findings, while only hypothesis generating, propose GPVI as a potential therapeutic target to mitigate thrombosis in ET patients, paving the way for targeted interventions in this high-risk population.

Clinical characteristics in adolescents and young adults with polycythemia vera and essential thrombocythemia in Japan

Clinical characteristics in adolescents and young adults with polycythemia vera and essential thrombocythemia in Japan

New approaches to standard of care in early-phase myeloproliferative neoplasms: can interferon-α alter the natural history of the disease?

The classical BCR::ABL-negative myeloproliferative neoplasms (MPN) include Polycythemia Vera (PV), Essential Thrombocytemia (ET), and Primary Myelofibrosis (PMF). They are acquired clonal disorders of the hematopoietic stem cells (HSC) leading to hyperplasia of one or several myeloid lineages. MPN are caused by three main recurrent mutations, JAK2V617F and mutations in the calreticulin (CALR) and the thrombopoietin receptor (MPL) genes. Here, we review the general diagnosis, the complications, and the management of MPN. Second, we explain the physiopathology of the natural disease development and its regulation, which contributes to MPN heterogeneity. Thirdly, we describe the new paradigm of the MPN development highlighting the early origin of driver mutations decades before the onset of symptoms and the consequence on early detection of MPN cases in the general population for early diagnosis and better medical management. Finally, we present the interferon alpha (IFNα) therapy as a potential early disease-modifying drug after reporting its good hematological and molecular efficacies in ET, PV and early MF in clinical trials as well as its mechanism of action in pre-clinical studies. As a result, we may expect that, in the future, MPN patients will be diagnosed very early during the course of disease and that new selective therapies under development, such as IFNα, JAK2V617F inhibitors and CALRmut monoclonal antibodies, would be able to intercept the mutated clones.

Essential thrombocythemia complicated by multivessel intracranial dolichoectasia with subarachnoid hemorrhage and recurrent cerebral infarction

BackgroundPatients with essential thrombocythemia (ET) can develop systemic thrombotic and hemorrhagic vascular complications due to increased and dysfunctional platelets.Case presentationWe encountered a 49-year-old Japanese woman with a history of essential ET, cerebral infarction, hypertension, and hyperlipidemia. She had been taking anagrelide (2.5 mg/day) and aspirin (100 mg/day) and had vomited at home. At the time of admission to our hospital, she was in a deep stupor. We thought these symptoms were caused by intracranial hypertension. Head computed tomography showed severe subarachnoid hemorrhage (SAH) at the interhemispheric fissure, hematoma at the corpus callosum, and intraventricular hemorrhages. Digital subtraction angiography demonstrated multiple dilated, stenotic, tortuous intracranial arteries, and a dissecting aneurysm at the right anterior cerebral artery (ACA). The dissecting aneurysm measured 7.7 × 15.5 mm, and a bleb was observed. Our diagnosis was ruptured ACA dissecting aneurysm and diffuse intracranial arterial dolichoectasia (DIADE). We performed stent-assisted coil embolization of the aneurysm. She remained apathetic and manifested unilateral apraxia and alien limb syndrome due to a partial callosal disconnection. Two months thereafter her symptoms gradually improved, her consciousness level and limb function improved, and her modified Rankin scale (mRS) score was 2. However, when we tapered her antiplatelet therapy, she again developed an acute cerebral infarct.ConclusionsThis is the first presentation of a patient with ET complicated by DIADE, both of which can result in ischemic and hemorrhagic vascular complications including SAH. As antithrombotic therapy in patients with DIADE and ET may be associated with higher hemorrhage rates, its effects must be monitored carefully.

Newly diagnosed essential thrombocythemia leading to cardiogenic shock: a case report

BackgroundEssential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by uninhibited platelet production. It can present with vasomotor symptoms, and less commonly, severe thrombotic events such as myocardial infarction. ST-segment elevation myocardial infarction (STEMI) secondary to the hypercoagulable state in ET is a diagnostic challenge as the complication is rare, especially outside the typical demographics affected by ET such as the female and elderly populations.Case presentationHere we report a case of a 32-year-old male found to have STEMI and a markedly elevated platelet count. Angiography revealed occlusion of the left anterior descending and left circumflex arteries, requiring percutaneous intervention and Impella support. The patient was later diagnosed with essential thrombocythemia, treated with hydroxyurea and antiplatelet therapy, and discharged with a wearable cardioverter defibrillator.ConclusionsThis case illustrates the potential for severe thrombotic complications such as STEMI due to ET. Severe thrombotic complications are less common manifestations of ET in general, particularly in young males. Recognition and diagnosis of ET are critical for the institution of appropriate therapy and prevention of STEMI and cardiogenic shock among other complications.

Report of 3 Cases Diagnosed with Basal Cell Carcinoma and Systemic Mastocytosis with Favorable Prognosis

Abstract Introduction/Objective The co-existence of basal cell carcinoma (BCC) and systemic mastocytosis is an exceptionally rare clinical occurrence, and the prognosis is not well-documented. Understanding the clinical and histopathological features of this uncommon association is relevant for accurate diagnosis, management, and prognostication. Methods/Case Report We conducted a retrospective analysis of three cases of BCC with concurrent systemic mastocytosis that were identified in the pathology database of the University of Pennsylvania from 2010 to 2023. Patient demographics, clinical and histopathologic characteristics, and treatment outcomes were reviewed. Histopathologic assessment, immunohistochemistry, and C-KIT D816V mutation analysis (with an allele-specific PCR assay) were performed on biopsy material. Next-Generation Sequencing (NGS) was used to identify other hematologic neoplasm-associated mutations. Results (if a Case Study enter NA) All three cases were female with a median age of 55.3 years (50, 69, 47). In all three cases, atypical CD117+ tryptase+ CD25+ mast cells with mild to moderate pleomorphism were found in the dermis adjacent to the BCC cells. All three cases had bone marrow involvement. Serum tryptase levels were mildly elevated in all 3 patients (maximum 65.5 μg/L). All three cases harbor a C-KIT D816V mutation and a history of systemic glucocorticosteroids before the diagnosis of BCC. One of the cases was treated with phototherapy. NGS detected the following somatic mutations: Case #2 DNMT3A p.R882H c.2645G>A; Case #3 JAK2 V617F. Case #1 had multiple relapses of BCC, but a subsequent marrow biopsy did not identify any involvement by mastocytosis. Case #2 had mast cell leukemia, which typically has a poor prognosis; however, this patient has survived for several years. Case #3 had essential thrombocythemia and systemic mastocytosis with an associated hematological neoplasm, and her symptoms were stable. Treatment modalities for the three patients ranged from surgical excision to anti-mastocytosis therapy, with favorable outcomes (Table 1). Conclusion The coexistence of BCC with mastocytosis poses diagnostic challenges due to its infrequency and varied clinical presentations. Previous literature reports on treatments of mastocytosis such as phototherapy and steroids, which have been identified as risk factors for the development of basal cell carcinoma. However, recognizing this unique combination in clinical practice may aid in providing appropriate treatment strategies, ultimately leading to favorable patient outcomes.

Possibilities for diagnosing essential thrombocythemia at the stage of primary health care

This clinical case presents a 39-year-old woman diagnosed with essential thrombocythemia, accompanied by a review of the epidemiology, clinical and diagnostic criteria, and patient management strategies. The case also includes a discussion of potential complications and prognosis associated with the condition. The importance of thorough outpatient monitoring is emphasized, which should include regular assessments of clinical symptoms, changes in blood count parameters, bone marrow trephine biopsy, and molecular genetic testing for MPL and CALR gene mutations. The report highlights gaps in the current medical examination process, suggesting that addressing these deficiencies could improve early detection of essential thrombocythemia and enable timely pathogenetic therapy with antiplatelet agents to prevent complications.

Childhood and adolescent essential thrombocythemia and prefibrotic primary myelofibrosis: insights into diagnosis, outcomes, and treatment from a large Chinese cohort.

The paucity of essential thrombocythemia (ET) and prefibrotic primary myelofibrosis (pre-PMF) in individuals younger than 18 years highlights several unresolved issues in diagnosis, clinical outcomes, and treatment strategies. To address these knowledge gaps, we analyzed a large bidirectional cohort consisting of childhood and adolescent ET (CAA-ET, n = 156) and pre-PMF (CAA-preMF, n = 13), as well as adult ET (n = 349). We introduced immunophenotypic abnormalities as novel clonal markers in CAA-ET and CAA-preMF, establishing a comprehensive method for clonal marker detection that integrated driver and non-driver mutations, positive endogenous erythroid colony formation, immunophenotypic abnormalities, and chromosomal aberrations. Next-generation sequencing revealed distinct mutational profiles between CAA-ET and adult ET, along with different age-related trends in the distribution of driver mutations. Venous thrombosis was more prevalent in CAA-ET, with JAK2 V617F emerging as a potential risk factor (P = 0.018). Immunophenotypic abnormalities were identified as risk factors for disease progression (P = 0.027). Significant differences between expected and actual treatment practices were identified. Compared to CAA-ET, CAA-preMF demonstrated poorer progression-free survival (P < 0.001) and faster disease progression (P = 0.019). This study provides a critical foundation for refining diagnostic, prognostic, and therapeutic approaches for CAA-ET and CAA-preMF.

"Y appearance" infarction: caused by essential thrombocythemia.

Essential thrombocythemia (ET) is a myeloproliferative malignancy caused by the excessive proliferation of megakaryocytes in the bone marrow, resulting in the overproduction of peripheral platelets. ET can lead to thrombotic events, such as ischemic stroke (IS), though it is a rare cause of IS. Bilateral medial medullary infarction (BMMI), also known as "Y appearance" infarction due to its distinctive imaging morphology, is a rare clinical subtype of IS which typically has a poor prognosis and a high mortality rate. Herein, we report the case of a 43-year-old male with a history of ET. The patient's platelet count was poorly controlled, and he did not receive regular treatment. After developing symptoms such as dizziness, dysphagia, choking on water, slurred speech, blurred vision, and bilateral limb numbness. Head magnetic resonance imaging revealed a "Y appearance" infarction in the bilateral medial medulla. After admission, the patient was administered intravenous antiplatelet therapy with tirofiban. However, when he was switched to oral aspirin after three days, he experienced decreased muscle strength and worsening symptoms. Therefore, tirofiban was continued for 14 days. Upon discharge, the patient experienced residual limb numbness. His National Institutes of Health Stroke Scale score was 1, Modified Rankin Scale score was 0, and platelet count had decreased to the normal range. During the 9-month follow-up period after discharge, the patient still had only mild limb numbness. Our report presents a special case of "Y appearance" infarction due to ET. Owing to fluctuations in the patient's condition, he received long-term high-dose tirofiban, which ultimately led to a significant improvement in his symptoms.

Early intervention prevented intrauterine fetus death due to placental abruption in woman with JAK2V617F mutation-positive essential thrombocythemia.

Early intervention prevented intrauterine fetus death due to placental abruption in woman with JAK2V617F mutation-positive essential thrombocythemia.

Relation of JAK2 V617F allele burden and coronary calcium score in patients with essential thrombocythemia.

JAK2 V617F (JAK2) mutation is associated with clonal hemopoiesis in myeloproliferative neoplasms as well as with faster progression of cardiovascular diseases. Little is known about the relationship between allele burden and the degree of atherosclerotic alteration of coronary vasculature. We previously reported that carotid artery stiffness progressed faster in patients with JAK2 positive essential thromocythemia (ET) patients. After a four-year follow-up we investigated whether mutation burden of a JAK2 allele correlates with a higher coronary calcium score. Thirty-six patients with JAK2 positive ET and 38 healthy matched control subjects were examined twice within four years. At each visit clinical baseline characteristics and laboratory testing were performed, JAK2 mutation burden was determined, and coronary calcium was measured. JAK2 allele burden decreased in 19 patients, did not change in 5 patients, and increased in 4 patients. The coronary calcium Agatston score increased slightly in both groups. Overall, there was no correlation between JAK2 allele burden and calcium burden of coronary arteries. However, in patients with the JAK2 mutation burden increase, the coronary calcium score increased as well. The average JAK2 allele burden decreased in our patients with high-risk ET during the four-year period. However, in the small subgroup whose JAK2 mutation burden increased the Agatston coronary calcium score increased as well. This finding, which should be interpreted with caution and validated in a larger group, is in line with emerging evidence that JAK2 mutation accelerates atherosclerosis and can be regarded as a non-classical risk factor for cardiovascular disease.

Essential thrombocythemia (ET) presenting as a combined cilioretinal artery occlusion (Cil.RAO) and central retinal vein occlusion (CRVO)

A 35-year-old male presented with sudden vision loss in his left eye for 1 day and was diagnosed with combined cilioretinal artery occlusion (Cil.RAO) and central retinal vein occlusion (CRVO). A multidisciplinary clinical work up was conducted to determine the underlying cause. A full blood count revealed a very high platelet count (1,147,000/mm3), prompting further hematologic investigation. Peripheral blood smear showed abundant platelet clumps, and bone marrow trephine biopsy indicated megakaryocytic hyperplasia and reticulin fibrosis (grade 1). The patient tested heterozygous for the JAK2 V617F mutation, a genetic marker for myeloproliferative disorders, and was diagnosed with essential thrombocythemia (ET). After a month of treatment with hydroxyurea 500 mg daily, his platelet count returned to normal. Thrombocythemia is associated with systemic and ocular thrombotic and embolic complications. A full blood count was pivotal in diagnosing and managing ET in this patient with combined retinal vascular disease.

S3786 Challenges in the Management of Upper GI Bleeding in a Patient With Essential Thrombocythemia and Gastroesophageal Varices

S3786 Challenges in the Management of Upper GI Bleeding in a Patient With Essential Thrombocythemia and Gastroesophageal Varices

Analysis of Incidence Rate, Risk Factors and Prognosis of Pulmonary Hypertension in Ph-MPNs Patients

To explore and analyze the incidence rate, influencing factors and impact on prognosis of pulmonary hypertension (PH) in patients with Philadelphia chromosome negative myeloproliferative neoplasms (Ph- MPNs). The clinical data of 271 patients with Ph- MPNs were retrospectively analyzed, and different disease subtypes were classified. Patients with different disease types were further divided into PH+ and PH- groups according to whether HP occurred. Statistical methods were used to analyze the incidence rate, risk factors, and impact on prognosis of PH in Ph- MPNs patients. The overall incidence rate of PH among 271 patients was 26.9%, and according to the classification of disease subtypes, it was found that the incidence rate of PH in patients with primary myelofibrosis (PMF) was significantly higher than those of patients with polycythemia vera and essential thrombocythemia (both P <0.05). Multivariate regression analysis showed that advanced age, long disease course, JAK2 positive and increased hematocrit, lactate dehydrogenase, monocyte count, and uric acid level were independent risk factors for PH in Ph- MPNs patients (OR >1, P <0.05), and there were some differences in the independent risk factors between different disease subtypes. Survival analysis results showed that the overall survival (OS) rate of PH+ patients was significantly lower than that of PH- patients in other types except for PMF (all P <0.05). The incidence rate of PH in Ph- MPNs patients is high, and its risk factors are diverse. The OS rate of Ph- MPNs patients with PH is low. Therefore, we should be highly alert to the occurrence of PH in Ph- MPNs patients clinically.

Budd Chiari syndrome (BCS) and Myeloproliferative Neoplasms (MPN): A Moroccan Experience Center

Background and Objectives: Budd–Chiari syndrome is a vascular disorder of the liver which can cause fulminant liver injury and lethal portal hypertension-related complications. It is a rare disease and can be primary or secondary. The objective of our work is to detail evolution, treatment of patients with BCS and MPN according to the experience of a Moroccan center. Patients and Methods: This is a retrospective and descriptive study in the university hepato-gastroenterology department including all patients with BCS and MPN with portal hypertension (PH) over a period of 29 years. All our patients benefited from an etiological work-up and morphological explorations. Results: Out of a total 29 patients had BCS, 4 had MPN with a prevalence of 10%. Clinically, the signs of decompensated PH were predominant. Imaging confirmed BCS. The etiological work-up showed that all our patients had essential thrombocytemia. We had also association of other prothrombotic factors in 50 % of cases and a portal thrombosis in 25% of cases. Our patients had received treatment for the causative disease and treatment of thrombosis associated with the treatment of PH complications. The evolution was marked by the death of 2 patients (50%). Conclusion: The strong association between MPN and BCS is well established. The knowledge of the molecular mutations underlying MPN has dramatically improved in the last decade, allowing early diagnosis of MPN in a significant portion of BCS patient.

Characterization of myeloproliferative neoplasms based on genetics only and prognostication of transformation to blast phase.

Myeloproliferative neoplasms (MPN) are a heterogeneous group of clonal disorders characterized by aberrant hematopoietic proliferation and an intrinsic risk of progression to blast phase. The WHO classification 2022 identifies chronic myeloid leukemia and the BCR::ABL1 negative MPNs polycythemia vera, primary myelofibrosis and essential thrombocythemia as individual entities. However, overlaps, borderline findings or transitions between MPN subtypes occur and incomplete clinical data often complicates diagnosis. By conducting a thorough genetic analysis, we've developed a model that relies on 12 genetic markers to accurately stratify MPN patients. The model can be simplified into a decision tree for routine use. Comparing samples at chronic and blast phase revealed, that one third of patients lost their MPN driver-gene mutation, while mutations in splicing and chromatin modifying genes were stable, indicating a shared founder clone of chronic and blast phase with different driver mutations and therefore different progressing capacities. This was further supported by gain of typical de novo AML gene mutations, accompanied by gain of complex karyotypes and RAS pathway gene mutations. Our data suggest to perform a broader genetic screening at diagnosis and also at clinical progression, as driver mutations may change and the MPN-driver mutations present at diagnosis may disappear.

Prognostic value of response to first-line hydroxyurea according to IPSET stratification in essential thrombocythemia.

Hydroxyurea (HU) constitutes the first-line treatment in most patients with essential thrombocythemia (ET), but criteria for changing therapy are not clearly established. The prognostic value of complete hematological response (CHR) and resistance/intolerance to HU was assessed in 1080 patients from the Spanish Registry of ET, classified according to revised IPSET-Thrombosis stratification (Very low- n = 61, Low- n = 83, Intermediate- n = 261, and High-risk n = 675). With a median therapy duration of 5 years, CHR was registered in 720 (67%) patients (1-year probability 51%) and resistance/intolerance in 219 (20%) patients (5-years probability 13%). After correction by other risk factors, High-risk patients achieving CHR showed a reduced risk of arterial thrombosis (HR: 0.35, 95%CI: 0.2-0.6, p = 0.001) and a trend towards lower risk of venous thrombosis (HR: 0.45, 95%CI: 0.2-1.02, p = 0.06) whereas no association was observed for intermediate- or low-risk patients. In comparison with non-responders, intermediate- and high-risk patients achieving CHR had longer survival and lower myelofibrosis incidence. Development of resistance/intolerance to HU, mainly cytopenia, was associated with higher probability of myelofibrosis but no effect on survival or thrombotic risk was demonstrated. In conclusion, CHR with HU is associated with better outcomes and might be an early indicator for selecting candidates to second-line clinical trials.

Reduced platelet activation in triple-negative essential thrombocythemia compared with JAK2V617F-mutated essential thrombocythemia.

Triple-negative (TN) essential thrombocytopenia (ET) is characterized by the absence of driver mutations while retaining histological and phenotypic characteristics sufficient for an ET diagnosis. Our understanding of TN-ET and its platelet activation remains incomplete. We carried out a large-scale multi-center clinical analysis to analyze the clinical and molecular characteristics, thrombotic complications of TN-ET. We also related the above characteristics to platelet activation to further explore the thrombosis mechanism of TN-ET. A retrospective multicenter study was conducted on 138 TN-ET and 759 ET patients with driver mutations from 1 March 2012 to 1 December 2021. The clinical and molecular characteristics of the TN-ET were summarized. Additionally, platelet activation, apoptosis, and reactive oxygen species (ROS) levels were analyzed in 73 TN-ET patients from this cohort and compared to 41 age- and sex-matched healthy donors. Compared to patients with the JAK2V617F mutation, those with triple-negative mutation were younger (P < 0.001) and exhibited fewer thrombotic events before diagnosis (P < 0.001) and during follow-up (P = 0.039). Patients with triple-negative mutation also presented with significantly reduced CD62P expression in platelets (P = 0.031), slightly reduced calcium concentration in platelets (P = 0.063), increased mitochondrial membrane potential (P = 0.011), reduced phosphatidylserine exposure (P = 0.015), reduced levels of ROS (P = 0.043) and MitoSOX in platelets (P = 0.047). In comparison to JAK2V617F-mutated ET, TN-ET is associated with lower platelet ROS levels, which leads to reduced platelet activation and consequently a lower risk of thrombosis.