Somatic RAP1B gain-of-function variant underlies isolated thrombocytopenia and immunodeficiency.

The ubiquitously expressed small GTPase Ras-related protein 1B (RAP1B) acts as a molecular switch that regulates cell signaling, cytoskeletal remodeling, and cell trafficking and activates integrins in platelets and lymphocytes. The residue G12 in the P-loop is required for the RAP1B-GTPase conformational switch. Heterozygous germline RAP1B variants have been described in patients with syndromic thrombocytopenia. However, the causality and pathophysiological impact remained unexplored. We report a boy with neonatal thrombocytopenia, combined immunodeficiency, neutropenia, and monocytopenia caused by a heterozygous de novo single nucleotide substitution, c.35G>A (p.G12E) in RAP1B. We demonstrate that G12E and the previously described G12V and G60R were gain-of-function variants that increased RAP1B activation, talin recruitment, and integrin activation, thereby modifying late responses such as platelet activation, T cell proliferation, and migration. We show that in our patient, G12E was a somatic variant whose allele frequency decreased over time in the peripheral immune compartment, but remained stable in bone marrow cells, suggesting a differential effect in distinct cell populations. Allogeneic hematopoietic stem cell transplantation fully restored the patient's hemato-immunological phenotype. Our findings define monoallelic RAP1B gain-of-function variants as a cause for constitutive immunodeficiency and thrombocytopenia. The phenotypic spectrum ranged from isolated hematological manifestations in our patient with somatic mosaicism to complex syndromic features in patients with reported germline RAP1B variants.

Risk Factors of Sepsis-Associated Thrombocytopenia among Patients with Sepsis Induced Coagulopathy.

The study aims to evaluate the prognosis and risk factors of sepsis-associated thrombocytopenia (SAT) among patients with coagulopathy, and to provide evidence of the relationship between adverse outcomes and potential risks. Patients with sepsis-associated coagulopathy were included in the study from January 2014 to December 2022. The primary outcome was sepsis-associated thrombocytopenia (platelet count less than 100 *109/L), which was evaluated by logistic regression models adjusted for demographic characteristics and comorbidities. Among patients in the SAT group, 54% developed severe SAT, while 16% of these patients recovered from thrombocytopenia. The in-hospital mortality rate was significantly higher in the SAT group compared to the non-SAT group (31% in SAT group vs 23.9% in non-SAT group, p = 0.029). Even after adjusting for age, gender, Charlson comorbidity, white blood cell, and Sequential Organ Failure Assessment score, the differences in mortality rate persisted (Odds Ratio 0.72, [95% Confidence Interval 0.52-0.92]). Correlation analyses revealed that prothrombin time (r = 0.08, p = 0.50), international normalized ratio (r = 0.08, p = 0.42), prothrombin activity (r = -0.06, p > 0.999), D-dimer (r = -0.02, p > 0.999), and inflammatory parameters such as C-reactive protein (r = -0.11, p = 0.37) were not significantly correlated with platelet counts. According to subgroup analyses, patients with lung infection complicated by SAT had slightly higher mortality (OR 0.66, [95% CI, 0.46 to 0.94]). Sepsis-associated coagulopathy indicates a subset of critical ill patients, with those experiencing thrombocytopenia at greater risk for in-hospital death compared to those without it.

Risk factors for linezolid - induced haematological toxicity in patients: a retrospective study.

INTRODUCTION: This single-center, observational cohort study aimed to investigate the risk factors associated with linezolid-induced hematological toxicity by analyzing the linezolid trough concentration (Cmin) obtained from patients undergoing treatment between January 2020 and December 2021. METHODOLOGY: A total of 111 eligible individuals were included in the study, of which 47 were diagnosed with linezolid-induced thrombocytopenia and 18 were diagnosed with linezolid-induced hemoglobin decrease. RESULTS: Binary logistic regression analysis revealed that creatinine clearance level (Ccr) < 50 mL/min/1.73 m2 (OR, 5.463; 95% CI, 1.249-23.888, p = 0.024) and Cmin > 7 mg/L (OR, 62.660; 95% CI, 14.293-274.708, p = 0.001) were risk factors associated with linezolid-induced thrombocytopenia. Area under the ROC curve for Cmin was 0.955, with a maximum Youden index of 0.837. The corresponding critical value was 6.94 mg/L (sensitivity 91.5%; specificity 92.2%). Ccr < 50 mL/min/1.73 m2 (OR, 7.282; 95% CI, 1.765-30.048, p = 0.006) and Cmin > 7mg/L (OR, 6.364; 95% CI, 1.937-20.910, p = 0.020) were found to be associated with linezolid-induced hemoglobin reduction. The area under the ROC curve for Cmin was 0.755, Youden index was 0.477 at the maximum, and the corresponding critical value was 7.53 mg/L (sensitivity 77.8%; specificity 69.9%). CONCLUSIONS: Renal insufficiency is a related risk factor for linezolid-induced hematological toxicity. Patients receiving linezolid treatment should be closely monitored with blood routine and plasma concentration, particularly in patients with moderate or severe renal insufficiency. The plasma trough concentration of linezolid could be a suitable predictor for linezolid-induced thrombocytopenia and anemia.

Procalcitonin levels in severe fever with thrombocytopenia syndrome patients: a retrospective investigation in Anhui, China.

INTRODUCTION: This work aim to evaluate the association of procalcitonin (PCT) levels with disease severity and prognosis in severe fever with thrombocytopenia syndrome (SFTS) patients. METHODOLOGY: The medical records of 158 confirmed SFTS patients at two hospitals were reviewed. The patients were divided into survival group and nonsurvival group according to outcomes. Additionally, to assess mortality rates at different PCT levels, patients were divided into two groups, PCT < 0.25 ng/mL and PCT ≥ 0.25 ng/mL. RESULTS: Among the 158 confirmed SFTS patients, 26 died; the case fatality rate was 16.46%. PCT data were available for 132 of these patients; 66 were in the PCT < 0.25 ng/mL group, and 66 were in the PCT ≥ 0.25 ng/mL group. The SFTS patients had abnormal results on routine blood tests, indicating varying degrees of thrombocytopenia and leukopenia, and most patients presented with multiple organ dysfunction. The PCT level of the nonsurvival group was significantly higher than that of the survival group (p < 0.01). Additionally, the mortality of the PCT ≥ 0.25 ng/mL group was significantly higher than that of the PCT < 0.25 ng/mL group (p < 0.01); mortality increased sharply ( ≥ 25%) when the PCT level exceeded 0.1 ng/mL. CONCLUSIONS: PCT levels in SFTS patients are closely related to the severity and prognosis of their illness. The serum PCT level is a promising predictor of mortality and severity in SFTS patients when considered in combination with clinical data and other laboratory tests.

Determinants of mortality in relationship between clinical and laboratory characteristics with the outcomes of children with diphtheria: A cross-sectional study at a national hospital of Sumatra region in 2020- 2023.

In 2017, diphtheria outbreaks occurred in several provinces in Indonesia; however, the epidemiological data in the country is limited. The aim of this study was to determine the association between clinical findings and laboratory parameters associated with mortality of children with diphtheria. A retrospective cohort study was conducted at Haji Adam Malik General Hospital, Medan, Indonesia, covering diphtheria patients from January 2020 to December 2023. All patients aged 1-18 years clinically diagnosed with diphtheria were considered eligible. The associations between demographic characteristics, clinical features, immunization status, complications, and laboratory profiles with mortality were determined using Fisher's exact test, and the odds ratio (OR) with a 95% confidence interval (95%CI) was calculated. Our data indicated that the clinical characteristics of myocarditis (p=0.005) and airway obstruction (p=0.003) were associated with mortality. There was also a significant association between thrombocytopenia (p=0.020) and mortality in diphtheria patients. Patients with airway obstruction were 13 times more likely to have an increase in mortality compared to patients without airway obstruction. This study highlights that clinical and laboratory characteristics could be associated with in-hospital mortality of diphtheria cases, and therefore, pediatricians should be aware of the presence of those characteristics to prevent the mortality of the patients.

Analysis of influencing factors and construction of risk prediction model for postoperative thrombocytopenia in critically ill patients with heart disease.

OBJECTIVE: To analyze the influencing factors of postoperative thrombocytopenia in critically ill patients with heart disease and construct a nomogram prediction model. METHODS: From October 2022 to October 2023, 319 critically ill patients with heart disease who visited our hospital were collected and separated into postoperative thrombocytopenia group (n = 142) and no postoperative thrombocytopenia group (n = 177) based on their postoperative thrombocytopenia, Logistic regression analysis was applied to screen risk factors for postoperative thrombocytopenia in critically ill patients with heart disease; R software was applied to construct a nomogram for predicting postoperative thrombocytopenia in critically ill patients with heart disease, and ROC curves, calibration curves, and Hosmer-Lemeshow goodness of fit tests were applied to evaluate nomogram. RESULTS: A total of 142 out of 319 critically ill patients had postoperative thrombocytopenia, accounting for 44.51%. Logistic regression analysis showed that gender (95% CI 1.607-4.402, P = 0.000), age ≥ 60 years (95% CI 1.380-3.697, P = 0.001), preoperative antiplatelet therapy (95% CI 1.254-3.420, P = 0.004), and extracorporeal circulation time > 120 min (95% CI 1.681-4.652, P = 0.000) were independent risk factors for postoperative thrombocytopenia in critically ill patients with heart disease. The area under the ROC curve was 0.719 (95% CI: 0.663-0.774). The slope of the calibration curve was close to 1, and the Hosmer-Lemeshow goodness of fit test was χ2 = 6.422, P = 0.491. CONCLUSION: Postoperative thrombocytopenia in critically ill patients with heart disease is influenced by gender, age ≥ 60 years, preoperative antiplatelet therapy, and extracorporeal circulation time > 120 min. A nomogram established based on above multiple independent risk factors provides a method for clinical prediction of the risk of postoperative thrombocytopenia in critically ill patients with heart disease.

[Developments of high-throughput sequencing-based diagnosis of congenital thrombocytopenia/platelet disorders in a registry study].

Congenital thrombocytopenia/platelet disorders are heterogeneous disorders of platelet number and/or function. Pathogenic variants in the genes implicated in megakaryocyte differentiation and platelet formation cause thrombocytopenia in these patients. Recent advances have elucidated several causative genes for these disorders, but identifying the underlying causative genes remains challenging. Patients with these disorders often receive inappropriate treatments, including glucocorticoids and splenectomy, for chronic immune thrombocytopenia (ITP). In Japan, we have developed a diagnostic system using high-throughput DNA sequencing with a multigene panel and established a registry. Between 2018 and 2023, 245 patients were enrolled and analyzed. Pathogenic variants in 17 genes (42 MYH9, 19 ANKRD26, 17 ITGA2B/ITGB3, 8 ACTN1, 8 WAS, 6 ETV6, 6 VWF, 5 CYCS, and 14 others) were identified in 125 patients (51.0%). An additional 29 patients (11.8%) had suspected pathogenic variants under investigation. We also found that immature platelet fraction (IPF%) is useful in the differential diagnosis because the median IPF% in MYH9 disorders, 48.7%, was significantly higher than in all other groups (chronic ITP, 13.4%; controls, 2.6%). The results of this study provide new insight into congenital thrombocytopenia/platelet disorders.

Safety of Antiplatelet Therapy in Noncardioembolic Ischemic Stroke With Thrombocytopenia: The CASE II Study.

BACKGROUND: There is scant evidence regarding the safety of antiplatelet therapy in acute ischemic stroke (AIS) patients with thrombocytopenia. Our study aims to address this concern by examining AIS patients with thrombocytopenia from a large database in real-world settings. METHODS AND RESULTS: We included patients with AIS with a platelet count <100×109/L who had complete records of antiplatelet drug use. Those requiring anticoagulation or having contraindications to antiplatelet therapy were excluded. Short-term safety outcomes were in-hospital bleeding events, while the long-term safety outcome was 1-year all-cause mortality. A good clinical outcome was defined as functional independence, indicated by a modified Rankin Scale score of 0 to 2 at discharge. Propensity score matched analyses were used. We screened 169 423 patients with AIS from 90 stroke centers in the CASE II register, ultimately enrolling 2808 noncardioembolic patients with thrombocytopenia. In the propensity score matched analyses, no significant difference was observed between the antiplatelet and nonantiplatelet groups in terms of intracranial hemorrhage (odds ratio=0.855 [95% CI, 0.284-5.478]; P=0.160) or gastrointestinal bleeding (odds ratio=2.034 [95% CI, 0.755-5.478]; P=0.160). Antiplatelet therapy was associated with improved functional outcomes at discharge (odds ratio=1.405 [95% CI, 1.028-1.920]; P=0.033), and showed a trend towards reducing 1-year mortality (odds ratio=0.395 [95% CI, 0.152-1.031]; P=0.058). CONCLUSIONS: The use of antiplatelet therapy lessened as platelet count decreased in patients with AIS with thrombocytopenia. However, our findings suggest that antiplatelet medications remain safe and effective for this population.

Effective and safe use of intramuscular clozapine in a patient presenting with catatonia and thrombocytopenia.

Clozapine is the most effective medication for the management of treatment-resistant schizophrenia and schizoaffective disorder, and its discontinuation can pose significant challenges in treatment. We present a patient with a diagnosis of schizoaffective disorder who was stable on clozapine for a decade until discontinuation due to thrombocytopenia. She experienced a relapse of her illness, presenting with psychotic and catatonic features with poor oral intake and physical health complications requiring a lengthy admission to the hospital. There was a poor response to alternative antipsychotics and a full course of electroconvulsive therapy. Intramuscular (IM) clozapine was initiated due to catatonia and refusal to accept oral medications. After receiving 10 doses of IM clozapine, she started accepting oral clozapine and made a full recovery within a few weeks. The low platelet count was persistent, and a bone marrow biopsy showed results consistent with immune thrombocytopenia being the cause of that low platelet count.

Romiplostim in chemotherapy-induced thrombocytopenia: A review of the literature.

Chemotherapy-induced thrombocytopenia (CIT) is a common challenge of cancer therapy and can lead to chemotherapy dose reduction, delay, and/or discontinuation, affecting relative dose intensity, and possibly adversely impacting cancer care. Besides changing anticancer regimens, standard management of CIT has been limited to platelet transfusions and supportive care. Use of the thrombopoietin receptor agonist romiplostim, already approved for use in immune thrombocytopenia, has shown promising signs of efficacy in CIT. In a phase 2 prospective randomized study of solid tumor patients with platelet counts <100 × 109/L for ≥4 weeks due to CIT, weekly romiplostim corrected the platelet count to >100 × 109/L in 93% (14/15) of patients within 3 weeks versus 12.5% (1/8) of untreated patients (p < 0.001). Including patients treated with romiplostim in an additional single-arm cohort, 85% (44/52) of all romiplostim-treated patients responded with platelet count correction within 3 weeks. Several retrospective studies of CIT have also shown responses to weekly romiplostim, with the largest study finding that poor response to romiplostim was predicted by tumor invasion of the bone marrow (odds ratio, 0.029; 95% CI: 0.0046-0.18; p < 0.001), prior pelvic irradiation (odds ratio, 0.078; 95% CI: 0.0062-0.98; p = 0.048), and prior temozolomide treatment (odds ratio 0.24; 95% CI: 0.061-0.96; p = 0.043). Elsewhere, lower baseline TPO levels were predictive of romiplostim response (p = 0.036). No new safety signals have emerged from romiplostim CIT studies. Recent treatment guidelines, including those from the National Comprehensive Cancer Network, now support consideration of romiplostim use in CIT. Data are expected from two ongoing phase 3 romiplostim CIT trials.

Heparin Induced Thrombocytopenia Testing.

This article provides a comprehensive overview of Heparin-Induced Thrombocytopenia (HIT) with an emphasis on laboratory testing and advantages of automation. HIT is a critical condition arising from heparin exposure, leading to a contradictory combination of thrombocytopenia with an increased thrombosis risk. The article discusses HIT's history, clinical presentation, laboratory diagnosis, and management strategies. It highlights the importance of interdisciplinary collaboration for effective diagnosis and treatment, underscoring advancements in technology and targeted therapies that are shaping future approaches to HIT management.

Injuries and deaths following Covid-19 vaccination: The ethical and legal case for compensation.

In April 2024, in a class action suit for compensation to families of persons suffering injury or death after vaccination with AstraZeneca's (AZ) Covid-19 vaccine [1], the manufacturer admitted in a UK court that the Oxford-AZ Covid-19 vaccine could cause a rare and potentially fatal blood clotting disorder ("thrombosis with thrombocytopenia syndrome" or TTS, which when triggered by a vaccine is called "vaccine induced thrombocytopenia and thrombosis, or VITT) [2]. The AZ Covid-19 vaccine is a chimpanzee adenovirus vectored vaccine encoding the SARS-CoV2 spike protein (ChAdOx1-S) marketed under the names Covishield and Vaxzevria.

Pediatric TAFRO syndrome: A multi-institution case series illustrating clinical challenges and excellent outcomes.

A rare lymphoproliferative disorder involving thrombocytopenia (T), anasarca (A), fever (F), reticulin fibrosis (R), renal dysfunction (R), and organomegaly (O), called TAFRO syndrome, was first reported in 2010. Considered a variant of idiopathic multicentric Castleman's disease, the recent discovery and rarity of this syndrome pose challenges to diagnosis and management. Herein, we review three pediatric cases, including an infant, that illustrate the heterogeneity of TAFRO syndrome. Despite differences in presentation and treatment responses, all patients experienced excellent outcomes. This multi-institutional case series highlights the need to work toward earlier diagnosis and improved long-term management recommendations for patients with TAFRO syndrome.

Two delayed-diagnosis case reports of long-lasting thrombocytopenia with splenomegaly.

RATIONALE: Gaucher disease (GD) is a rare hereditary lysosomal storage disorder disease progression and inappropriate treatment. However, not all patients with GD receive timely diagnosis and treatment. PATIENT CONCERNS: Early diagnosis is important for initiating proper treatment and preventing complications. DIAGNOSES: Two patients were diagnosed as GD in this study. INTERVENTIONS AND OUTCOMES: These 2 patients received the imiglucerase enzyme replacement and symptoms significantly improved by the follow-up. LESSONS: Herein, we report 2 patients with a delayed diagnosis of GD to increase awareness and improve education regarding rare diseases. However, noninvasive ß-glucocerebrosidase activity or GBA gene testing had not been done before bone marrow aspiration, which are the noninvasive and reliable tests that indicate the diagnosis of GD.

Identification of Active Molecules against Thrombocytopenia through Machine Learning.

Thrombocytopenia, which is associated with thrombopoietin (TPO) deficiency, presents very limited treatment options and can lead to life-threatening complications. Discovering new therapeutic agents against thrombocytopenia has proven to be a challenging task using traditional screening approaches. Fortunately, machine learning (ML) techniques offer a rapid avenue for exploring chemical space, thereby increasing the likelihood of uncovering new drug candidates. In this study, we focused on computational modeling for drug-induced megakaryocyte differentiation and platelet production using ML methods, aiming to gain insights into the structural characteristics of hematopoietic activity. We developed 112 different classifiers by combining eight ML algorithms with 14 molecule features. The top-performing model achieved good results on both 5-fold cross-validation (with an accuracy of 81.6% and MCC value of 0.589) and external validation (with an accuracy of 83.1% and MCC value of 0.642). Additionally, by leveraging the Shapley additive explanations method, the best model provided quantitative assessments of molecular properties and structures that significantly contributed to the predictions. Furthermore, we employed an ensemble strategy to integrate predictions from multiple models and performed in silico predictions for new molecules with potential activity against thrombocytopenia, sourced from traditional Chinese medicine and the Drug Repurposing Hub. The findings of this study could offer valuable insights into the structural characteristics and computational prediction of thrombopoiesis inducers.

Hantavirus Cardiopulmonary syndrome: Another Reason to Avoid Mice.

Hantavirus cardiopulmonary syndrome is a severe illness transmitted by rodent excretions. We describe a case of a 24-year-old man who presented to the emergency department with cough, shortness of breath, chills, myalgias, nausea, and diarrhea. Physical examination and laboratory analysis revealed signs of respiratory distress and thrombocytopenia. The trajectory of his illness led to acute respiratory distress syndrome (ARDS) and hemodynamic instability. Serum testing was positive for hantavirus IgM and IgG antibodies. The patient was managed with supportive care and improved. This case highlights the importance of considering hantavirus when managing patients who develop thrombocytopenia, ARDS, and hemodynamic instability in the appropriate clinical setting.

Hematological abnormality and associated factors in newborns with hyperbilirubinemia before and after phototherapy at University of Gondar Comprehensive Specialized Hospital.

This study aimed to assess the magnitude of hematological toxicity and associated factors in newborns with hyperbilirubinemia. A cross-sectional study was conducted from April to December 2023. A total of 247 newborns were included. The data were collected using questionnaires and a data extraction sheet. Four 4 ml of blood was collected. A Sysmex KX-21 analyzer was used for blood analysis, and a Mindray BS-240 analyzer was used for bilirubin measurement. The data were entered into Epi-data and analyzed by SPSS. The logistic regression was used. The P value was set at 0.05. Before phototherapy, the hematological toxicities, such as anemia, leucopenia, and thrombocytopenia, were 45.7%, 22.2%, and 6.1%, respectively, whereas after phototherapy, anemia and thrombocytopenia, significantly increased, but the leucopenia, significantly decreased. The risk of developing anemia increased, 3.5, 2.7, and 2.1-fold among newborns with bilirubin > 18 mg/dl, with Rh blood group incompatibility, and treated with intensive phototherapy, respectively. Both low birth weight and intensive phototherapy increased the incidence of thrombocytopenia by 2 and 3.4-fold, respectively. Hematological toxicity was found to be a severe public health issue in newborns. Thus, strict follow-up and early detection of toxicity by considering aggravation factors are necessary.