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184 citation(s) found for "Chen, Dong".

Acute Myeloid Leukemia Subtype‐Specific Prognostic Value of NGS in the Setting of Intensive Chemotherapy
Bolarinwa, Abiola , Al‐Kali, Aref , Mangaonkar, Abhishek A. , Saliba, Antoine N. , Hefazi, Mehrdad , Matin, A, Elliott, Michelle A. , Litzow, Mark R. , Hogan, William J. , Patnaik, Mrinal M. , Pardanani, Animesh , Foran, James M. , Punwani, Nathan , Palmer, Jeanne , Sproat, Lisa Z., Reichard, Kaaren K., He, Rong , Viswanatha, David S., Zepeda‐Mendoza, Cinthya , Gangat, Naseema , Begna, Kebede H. , Tefferi, Ayalew , Saliba, Antoine N. , Alkhateeb, Hassan B , Mangaonkar, Abhishek A. , Saliba, Antoine N , Hefazi, Mehrdad , Elliott, Michelle , Litzow, Mark R. , Hogan, William J , Shah, Mithun V , Patnaik, Mrinal , Pardanani, Animesh , Foran, James M , Badar, Talha , Murthy, Hemant S , Chen, Dong , He, Rong , Zepeda-Mendoza, Cinthya J , Gangat, Naseema , Tefferi, Ayalew , Saliba, Antoine N , Bolarinwa, Abiola B , Alkhateeb, Hassan B. , Shah, Meera , Badar, Talha , Murthy, Hemant S. , Chen, Dong , Reichard, Kaaren K.

Mayo Clinic

American Journal of Hematology | July 18, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1002/ajh.70443 | PMID 42470254 Get It

ABSTRACT We examined the prognostic value of routine NGS data in newly diagnosed acute myeloid leukemia (AML) treated with intensive (7 + 3 backbone) induction, specified by AML subtype. A contemporary (2015–2025) series of 545 Mayo Clinic patients (median age 56 years, females 44%) was considered. Median follow‐up was 49 months with 341 (63%) allogeneic hematopoietic stem cell transplantations (AHSCT) recorded. AML subtypes included core‐binding factor (CBF; N = 72; 13%), primary non‐CBF ( N = 403; 74%), post‐myelodysplastic syndromes (MDS) or post‐myelodysplastic/myeloproliferative neoplasms (post‐MDS‐MDS/MPN; N = 28; 5%), post‐MPN ( N = 15; 3%), and therapy‐related (t‐AML; N = 27; 5%). Corresponding complete remission rates, with/without count recovery (CR/CRi), were 89%, 76%, 64%, 27%, and 78% ( p < 0.01) and 5‐year transplant‐censored survival rates 68%, 57%, 21%, 0%, and 55% ( p < 0.01). In multivariable analyses, the prognostic value of specific mutations was mostly limited to primary non‐CBF AML where adverse karyotype (OR 1.9; p = 0.04) predicted inferior and FLT3 ‐ITD (OR 0.4; p < 0.01) or NPM1 MUT / FLT3 WT (OR 0.1; p < 0.01) superior CR/CRi while KRAS MUT (HR 8.8; p < 0.01), TP53 MUT (HR 5.4; p < 0.01), and TET2 MUT (HR 2.3; p = 0.01) predicted inferior and NPM1 MUT / FLT3 WT (HR 0.3; p = 0.01) superior survival. Prognostication in intensively‐treated AML should start with subtype specification and recognition of the limited value of NGS in non‐primary AML. Post‐MPN AML is particularly associated with dismal outcomes and should be prognostically distinguished from post‐MDS‐MDS/MPN AML. In primary non‐CBF AML, in addition to previously established risk factors, the favorable impact of FLT3 ‐ITD on achieving CR/CRi and the unfavorable impact of KRAS MUT and TET2 MUT on transplant‐censored survival were noted and require confirmation from additional studies.
Pathogenic PF4 /Polyanion ELISA ‐Negative Antibodies in HIT
Kanack, Adam J. , Splinter, Noah P., Mauch, Emily, Gil, Morayma Reyes, Jasra, Sakshi , Goodwin, Andrew, Smock, Kristi J. , Ahmad, Hadiyah, Ashrani, Aneel A. , Robinson, Nathaniel L. , Jones, Curtis G., Pechauer, Shannon M., yttre, erin , Aster, Richard H. , Kohlhagen, Mindy , Leger, Rachel, Johns, Gretchen, Murray, David , Zhou, Lu, Wang, Demin, Wen, Renren , Chen, Dong, Pruthi, Rajiv K. , Padmanabhan, Anand , Wang, Demin , Zhou, Lu , Mauch, Emily E, Smock, Kristi J , Kohlhagen, Mindy C, Leger, Rachel R, Chen, Dong , Padmanabhan, Anand , Wang, Demin , Tefera, Leben T. , Gil, Morayma Reyes , Casanegra, Ana I. , Johns, Gretchen S.

Mayo Clinic

American Journal of Hematology | May 2, 2026 | Volume: 101 | Issue: 8 | Pages: 1790-1798

10.1002/ajh.70333 | PMID 42068120 Get It

ABSTRACT Background Platelet factor 4‐polyanion enzyme‐linked immunosorbent assays (ELISAs) are considered highly sensitive for diagnosing heparin‐induced thrombocytopenia (HIT), such that current practice guidelines recommend use of ELISA‐negative results to exclude HIT. Once HIT is ruled out, alternative, non‐heparin‐based anticoagulant treatments are ceased, and heparin reintroduction frequently occurs. Methods Antigen‐based and PF4‐dependent functional testing were used to study PF4/polyvinylsulfonate ELISA‐negative platelet‐activating antibodies in HIT‐suspected patients. Results Three patients with clinical presentations consistent with HIT tested negative in an ELISA using PF4‐polyvinylsulfonate (PF4/PVS), an antigenic target very commonly used for HIT antibody screening. All three patients demonstrated PF4‐dependent platelet activation in functional testing that was sensitive to blockade of platelet FcγRIIa receptors and inhibited by high concentrations of heparin, consistent with pathogenic HIT antibodies. Functional testing‐based screening of 500 ELISA‐negative patients identified three additional patients whose sera activated platelets in a PF4‐ and FcγRIIa‐dependent manner and had clinical histories consistent with HIT. Five of the six ELISA‐negative HIT patients were re‐exposed to heparin, which precipitated a decrease in platelet counts in all re‐exposed patients, and one patient developed a new thrombus. Conclusions Recognition of ELISA‐negative HIT is critical to avoid harm due to the cessation of alternative anticoagulation therapy and re‐exposure of these patients to heparin.
A Retrieval-Based Approach for Automatic Interpretation of Multi-Analyte Laboratory Profiles
Khandelwal, Sarthak, Leger, Rachel, Navitskas, Serena, Pruthi, Rajiv, Chen, Dong , Tavolara, Thomas E, Chen, Dong , Tavolara, Thomas Erol , Leger, Rachel, Navitskas, Serena D., Pruthi, Rajiv K. , Seheult, Jansen N.

Mayo Clinic

The Journal of Applied Laboratory Medicine | April 17, 2026 | Volume: No volume available | Issue: No issue available | Pages: No page available

10.1093/jalm/jfag063 | PMID 42189159 Get It

Abstract Background Interpretation of multi-analyte laboratory profiles, such as lupus anticoagulant (LAC) testing, requires integration of numerous test results and clinical information. However, this process is time-consuming, requires domain knowledge, and has limited scalability. Given that rule-based systems are rigid and difficult to maintain and large language models pose risks of “hallucinations,” we developed and evaluated a novel retrieval-based approach to automate LAC profile interpretation to improve efficiency while maintaining fidelity and reliability for clinical use. Methods Our method processes laboratory values through ensemble random forest (RF) models to retrieve the most similar expert interpretation from a curated database of 347 previously interpreted LAC profiles. The system's performance was assessed through technical accuracy metrics, a work flow efficiency timing study, and expert review of interpretation accuracy for held-out cases. Results Technical validation demonstrated high accuracy in retrieving correct interpretative elements (median: 93% accuracy, interquartile range [IQR]: 67% to 100%). Retrieval accuracy was highly correlated with the prevalence of a given element (ρ = 0.8307). In a timing study of 93 consecutive LAC profiles, ensemble-assisted interpretation achieved a median time of 22 s per report (IQR: 16 s to 31 s), representing a 78.6% total reduction compared to manual interpretation (median: 118 s, IQR: 96 s to 172 s; t = 18.61, P &lt; 0.001). Furthermore, 92.5% of AI-assisted interpretations were completed within 60 s, exceeding the target of 85%. Expert review confirmed 100% concordance for LAC presence/absence. Conclusions The proposed approach significantly improves efficiency of complex laboratory interpretation for LAC profiles, while maintaining consistency and high fidelity. Future studies will explore the method’s inherent extensibility to the interpretation of other multi-analyte laboratory profiles.
Assessment of Novel Platform of Thrombin Generation to Predict Venous Thromboembolism Early After Traumatic Injury: A Prospective Cohort Study
Thompson, Riley J., Spears, Grant M. , Bailey, Kent R., Pruthi, Rajiv K. , Jenkins, Donald H., Dong, Jing-Fei, Kozar, Rosemary A. , Park, Myung S., Pruthi, Rajiv, Navarro, Sergio M. , MacArthur, Taleen A. , Bailey, Kent R. , Chen, Dong , Jenkins, Donald H. , Dong, Jing-Fei

Mayo Clinic

Shock | April 8, 2026 | Volume: 66 | Issue: 2 | Pages: 441-448

10.1097/shk.0000000000002725 | PMID 41949808 Get It

Introduction: Calibrated automated thrombogram assay parameters have been shown to assess hypercoagulation state and, therefore, may independently predict posttrauma, symptomatic venous thromboembolism (VTE). Yet, calibrated automated thrombogram lacks high throughput and standardization, limiting diagnostic potential. This study analyzed thrombin generation (TG) profiles in trauma patients using a high-throughput assay, processing up to 10 samples at once, providing batch testing capabilities. We hypothesized that trauma patients who developed VTE would show distinct TG profiles compared with those who did not. Methods: Trauma patients presenting to a Level I Trauma Center had samples collected within 12 hours postinjury prospectively. Follow-up was conducted to 90 days, time to symptomatic VTE diagnosis or death, confirmed via autopsy or imaging. TG profiles were measured from the ST Genesia assay. Data were presented as median (interquartile ranges) or n (%), with the Wilcoxon rank-sum or chi-squared test. Associations between TG parameters and clinical risk factors were assessed using Spearman correlation analysis or the Wilcoxon rank-sum test. Results: Two hundred and fifty-four trauma patients were analyzed [48.5 years (31.0, 62.0), 72.0% male]: 64 patients with VTE (25.2%) to 190 with non-VTE. VTE pts had a median time to VTE of 8 days, with 29 developing deep venous thrombosis, 24 with pulmonary embolism, and 11 with deep venous thrombosis/pulmonary embolism. No significant differences were found in age, sex, or body mass index; significantly more VTE patients underwent surgery and blood transfusions within 24 hours. TG profiles demonstrated accelerated TG in patients who developed VTE compared with non-VTE, with significant differences in peak height ( P = 0.001), time to peak ( P = 0.021), endogenous thrombin potential ( P < 0.001), and velocity index ( P = 0.001). Conclusion: TG profiles using ST Genesia can differentiate trauma patients at high risk of developing VTE. The platform suits clinical labs needing high throughput by providing batch testing capabilities. Study type: Prospective study with less than large effect and no negative criteria. Level of evidence: II.
When estrogen sparks clotting: the lactoferrin-FXI link
Chen, Dong

Mayo Clinic

Blood | April 2, 2026 | Volume: 147 | Issue: 14 | Pages: 1518-1519

10.1182/blood.2025032335 | PMID 41926142 Get It

Circulating Nucleosomes are Elevated in Trauma Patients with Venous Thromboembolism: A Prospective Case-Cohort Study
Thompson, Riley J., Spears, Grant M. , Bailey, Kent R., Kelly, Theresa K., Wheeler, Christina, Dong, Jing-Fei, Kozar, Rosemary A. , Park, Myung S., Navarro, Sergio M. , Bailey, Kent R. , Kelly, Theresa Kathleen , Chen, Dong

Mayo Clinic

Shock | March 26, 2026 | Volume: 66 | Issue: 3 | Pages: 666-675

10.1097/shk.0000000000002807 | PMID 41886536 Get It

Objective: The identification of reliable biomarkers in trauma patients (pts) remains a clinical challenge. Nucleosomes, which are DNA wrapped around histone protein cores, have been used as reliable markers for quantification in sepsis, acute respiratory distress syndrome, and lymphoma. We hypothesized that: 1) levels of circulating nucleosomes quantified after traumatic injury, specifically histone H3.1 and its citrullinated R8 posttranslation modification (H3R8 Cit), would be increased after trauma and 2) that levels of circulating nucleosomes would be further, increased in pts who went on to develop venous thromboembolism (VTE), as these nucleosomes may be clot-enhancing mediators. Methods: Trauma pts presenting to a Level I trauma center were evaluated for inclusion in a prospective case-cohort study, and citrated blood samples were collected within 12 hours of injury. Pts were followed for up to 90 days and VTE occurrence was confirmed via autopsy or imaging. Pts who developed incident, symptomatic VTE, and those who did not develop VTE were selected at a 1:3 ratio. The effect of trauma was assessed by comparison with healthy volunteer samples. Circulating nucleosomes were quantified using Nu.Q H3.1 and Nu.Q H3R8 Cit assays. Data are presented as median [interquartile range] or n (%), with Wilcoxon Rank-Sum or chi-squared test performed between trauma pts who developed symptomatic VTE versus those who did not, with a P value < 0.05 as statistically significant. Results: A total of 639 trauma pts were analyzed [51 years (33, 65), 71.0% male, 94.1% blunt, injury severity scores 17 (9, 27)]. Both H3.1 [359.7 (58.4, 1769.3) vs. 21.5 (15.3, 26.6) ng/mL, P < 0.001] and H3R8 Cit levels [209.4 (45.4, 665.5) vs. 22.3 (16.2, 28.9) ng/mL, P < 0.001] were greater in trauma pts than in 10 healthy volunteers. The 160 pts with VTE were then compared with 479 without VTE. VTE pts had a median time to VTE of 8.5 days, with 91 developing symptomatic deep venous thrombosis, 48 with pulmonary embolism, and 21 with both deep venous thrombosis and pulmonary embolism. No significant differences were found in age, sex, or mechanism between pts with or without VTE. However, VTE pts had higher injury severity scores [24 (14, 34), 14 (9, 24), P < 0.001] and body mass index [29.1 (24.3, 34.2), 27.6 (24.2, 32.0) kg/m 2 , P = 0.037]. A greater percentage of VTE pts underwent surgery requiring general anesthesia (53.1%, 34.0%, P < 0.001) and received blood transfusions within 24 hours of injury (51.9%, 24.0%, P < 0.001). H3.1 levels were significantly greater in trauma pts who developed VTE compared with those who did not [828.4 (112.0, 3186.5), vs. 276.7 (50.3, 1237.0) ng/mL, P < 0.001], as were H3R8 Cit levels [350.4 (77.4, 729.5), vs. 189.2 (40.8, 632.6) ng/mL, P = 0.005]. No differences in levels of H3.1 and H3R8 Cit were found between early (diagnosed day 0–7 after injury) and late (diagnosed > day 7) VTE. Conclusions: Levels of the H3.1 and H3R8 Cit nucleosomes are elevated early after traumatic injury, especially in those who developed VTE. These findings underscore the importance of understanding the pathophysiology of nucleosomes in inducing VTE and their role as biomarkers
MAPS-R: International consensus classification-guided revision of the mayo alliance prognostic system for systemic mastocytosis
Tefferi, Ayalew , Aperna, Fnu, Kumar, Mahesh, Abdelmagid, Maymona, Butterfield, Joseph H. , Pongdee, Thanai , Reichard, Kaaren K. , Gangat, Naseema , Pardanani, Animesh , Yi, Cecilia Arana , Arber, Daniel A. , Orazi, Attilio , Chen, Dong

Mayo Clinic

Blood | December 5, 2025 | Volume: 146 | Issue: Supplement 1 | Pages: 2017-2017

10.1182/blood-2025-2017 Get It

Abstract Background: The International Consensus Classification (ICC) for systemic mastocytosis (SM) recognizes mast cell leukemia (MCL) and SM with associated myeloid neoplasm (SM-AMN) as distinct categories of advanced SM (SM-Adv; Arber et al. Blood 2022;140:1200). Contemporary risk models in SM, including the Mayo Alliance Prognostic System (MAPS), do not account for the prognostic heterogeneity among ICC-defined SM-Adv subcategories. Methods: Mayo Clinic databases were utilized to access patient information. Diagnoses of SM and its morphological subcategories were confirmed through clinical evaluations and review of BM pathology. Diagnostic criteria were retrospectively fitted to be consistent with those of the ICC (Arber et al. Blood 2022;140:1200); diagnosis of MCL required the presence of immature cytomorphology of mast cells and only myeloid neoplasms were listed under the category of SM-AMN.Next-generation sequencing and cytogenetic studies was performed in a subset of the study patients according to previously described methodologies. Statistical analyses were conducted on clinical and laboratory data collected at the time of initial diagnosis while survival analysis was censored at the time of allogeneic stem cell transplant (ASCT). Results: A total of 910 Mayo Clinic patients with SM (median age 56 years, range 12-89; males 50%) were accessed in order to conduct a series of multivariable analyses (MVA) in search of independent risk factors for transplant-censored overall survival (OS). All patients were evaluable for assignment to specific ICC categories of SM: indolent (ISM; N=553), aggressive (ASM; N=114), SM-AMN (N=235), and MCL (N=8); the AMN components in SM-AMN included acute myeloid leukemia (N=18), chronic myelomonocytic leukemia (N=70), myelodysplastic syndromes (N=32), MDS/myeloproliferative overlap (N=81), myelofibrosis (N=7), polycythemia vera or essential thrombocythemia (PV/ET; N=19), and others (N=8). In addition, subsets of patients were evaluable for hemoglobin level (N= 865), white blood cell count (WBC; N=858), platelet count (N= 859), serum alkaline phosphatase (ALP; N=761), serum tryptase level (N=706), karyotype (N=574), and mutations (N=240). Median follow-up for living patients was 70 months (range, 0-520); during this time 346 (38%) deaths, 16 leukemic transformations, and 20 ASCTs were documented. ROC analysis-determined optimal cutoff levels for predicting OS included age at ≥60 years, platelet count &lt;150 x 109/L, tryptase level ≥100 ng/mL, WBC ≥10 x 109/L, hemoglobin below sex-adjusted lower limit of normal (anemia), and ALP &gt;210 U/L in women or &gt;170 U/L in men (increased). All except WBC ≥10 x 109/L retained significance during MVA that included ICC-specified SM categories: MCL (HR 74.8, 26.0-215.3; p&lt;0.01); SM-AMN (HR 3.9, 2.5-6.0; p&lt;0.01); ASM (HR 2.2, 1.4-3.5; p&lt;0.01); age ≥60 years (HR 3.3, 2.2-4.7; p&lt;0.01); platelets &lt;150 x 109/L (HR 2.8, 2.0-3.9; p&lt;0.01); tryptase ≥100 ng/mL (HR 2.1, 1.5-2.9; p&lt;0.01); anemia (HR 1.7, 1.1-2.4; p&lt;0.01); and increased ALP (HR1.5, 1.1-2.0; p=0.01). A subsequent HR-weighted risk model effectively delineated 5 risk levels ranging in median survivals from 11 months to 372 months (Figure 1). Figure 2 outlines complementary subtype-specific risk models; to that end, risk factors for ISM included age ≥60 years (HR 4.5, 2.5-7.9), tryptase ≥100 ng/mL (HR 3.5, 2.1-6.0); platelets &lt;150 x 109/L (HR 3.4, 1.5-7.9), and anemia (HR 2.4, 1.2-4.8); for ASM age ≥60 years (HR 2.3, 1.3-4.3), platelets &lt;150 x 109/L (HR 2.4, 1.4-4.0), and anemia (HR 2.0, 1.2-3.4); and for SM-AMN age ≥60 years (HR 2.9, 1.6-5.2), platelets &lt;150 x 109/L (HR 2.5, 1.6-3.9), and tryptase ≥100 ng/mL (HR 2.5, 1.6-3.9) [Figure 2]. In SM-AMN, additional prognostic relevance from subcategorization into PV/ET vs. all other types of AMN was appreciated (Figure 3; HR 4.0, 1.6-3.9) and incorporated into the risk model for SM-AMN (Figure 2). Abnormal karyotype (AK) and high risk mutations(HRM; ASXL1, SRSF2, RUNX1, NRAS)clustered withSM-AMN with AK and ASXL1MUT displaying independent prognostic relevance that was most apparent in SM-AMN. Conclusions : MAPS-R relies on the prognostic eminence of ICC-defined morphologic subcategories and allows for additional SM subtype-specific risk stratification. SM associated with ET or PV is a prognostically unique subcategory of SM-AMN and should be recognized as such in future classification schemes. SM-AMN must be thoroughly ruled out in the presence of AK or HRM.
Anti-platelet factor 4 antibodies in MGUS-related thrombosis
Kanack, Adam J. , Splinter, Noah P., Mauch, Emily, Leger, Rachel, Shah, Surbhi , Kumar, Shaji , Pruthi, Rajiv K. , Padmanabhan, Anand , Houghton, Damon E. , Dispenzieri, Angela , Chen, Dong

Mayo Clinic

Blood | December 5, 2025 | Volume: 146 | Issue: Supplement 1 | Pages: 1321-1321

10.1182/blood-2025-1321 Get It

Abstract Introduction: Monoclonal gammopathy of thrombotic significance (MGTS) is a recently recognized thrombophilia where monoclonal platelet factor 4 (PF4)-specific IgG antibodies initiate a chronic prothrombotic state characterized by recurrent and potentially life-threatening thrombosis. Studies from large data sets demonstrate that patients with monoclonal gammopathy of undetermined significance (MGUS) have a heightened risk of experiencing thromboembolic events without a precise explanatory mechanism. The prevalence of MGTS in MGUS-related thrombosis is unknown; however, the recent identification of MGTS antibodies as a cause of thrombosis suggests a potentially causative mechanism. Emerging evidence indicates that detecting pathogenic MGTS antibodies presents diagnostic challenges due to the insensitivity of FDA-approved diagnostic assays adopted from HIT (HIT ELISAs) and gold-standard functional tests that use heparin-treated platelets, such as the serotonin release assay (SRA). Only PF4-enhanced functional assays, including the PF4-dependent P-selectin expression assay (PEA) and PF4-SRA, have proven sensitive for detecting MGTS antibodies. In this study, the PEA was utilized to better define the incidence of pathogenic anti-PF4 antibodies among a cohort of MGUS patients with a history of thrombosis. Methods: A search of the Mayo Clinic Dysproteinemia Bank was conducted to identify two cohorts of IgG MGUS patients, one with venous thromboembolism-associated diagnosis code(s) and the other without. A diagnosis of multiple myeloma was exclusionary. Each serum sample was assessed using the PEA. Mayo Clinic's Institutional Review Board approved the research study. Results: Among the 134 patients studied in the thrombosis cohort, 17 (13%) stimulated platelet activation in the PEA (positive cut-off ≥19%), some weakly. Of these, four patients (Patients 1-4) were confirmed to have PF4-dependent platelet-activating antibodies inhibitable with high concentrations of heparin and sensitive to blockade of the IgG receptor on platelets, FcGRIIa. The thrombotic complications experienced included recurrent deep venous thrombosis (DVT) over several years (Patient 1), a single DVT (Patient 2), a thrombotic cerebrovascular accident (CVA) (Patient 3), and a series of thrombotic events, including DVTs, left atrial thrombosis, pulmonary embolism, and acute limb ischemia (Patient 4). Notably, longitudinal samples spanning twelve years (Patient 1), six years (Patient 2), three years (Patient 3), and on a single sample date (Patient 4) were confirmed positive by PEA. The prolonged persistence of platelet-activating anti-PF4 antibodies in Patients 1-3 supported a diagnosis of MGTS in these patients. Strikingly, all four patients tested negative in two FDA-approved HIT ELISAs (Immucor PF4 IgG and Zymutest HIA IgG). SRA was negative for Patients 1 and 2, weakly positive for Patient 3 (33%), and positive for Patient 4 (72%). Of the 166 patients in the MGUS minus thrombosis cohort, one patient demonstrated a non-heparin induced HIT-like antibody that was HIT ELISA (Optical Density &gt;1.0) and PEA-positive, and inhibitable using high concentrations of heparin and FcGRIIa blockade. No follow-up samples were available to assess antibody longevity. The patient had no history of thrombosis, and testing demonstrated that the anti-PF4 antibody was not synonymous with the MGUS antibody.Conclusions: Among a cohort of 134 MGUS patients with thrombosis, the prevalence of MGTS was found to be 2.2% (3 patients with persistent platelet-activating anti-PF4 antibodies). The identification of anti-PF4 antibodies among MGUS patients provides a mechanism contributing to the increased thrombotic risk associated with monoclonal gammopathies. Antibody negativity in HIT ELISA and variable positivity in the SRA highlight the nonclassical serology associated with anti-PF4 antibodies in MGTS and support performing PF4-enhanced functional testing. In addition, some patients appear to produce coincidental (non-monoclonal) platelet-activating anti-PF4 antibodies without evidence of thrombosis, although the longevity of such antibodies could not be examined in the one patient where it was identified. These findings highlight the need for larger, prospective MGUS studies to validate these observations, further define the interplay between monoclonal gammopathies and thrombotic risk, and to better understand the long-term outcomes of patients with MGTS.