Showing papers on "Blood Platelet Disorders published in 2022"
TL;DR: This review of inherited thrombocytopenia syndromes highlights the important role for the clinician in identifying a germline genetic diagnosis, and strategies for identifying novel causes through research-based endeavors.
3 citations
TL;DR: In this paper , a review summarizes the approaches to morphologic phenotyping and platelet testing in patients with suspected platelet dysfunction, beginning with a standardized bleeding score and ending with flow cytometry testing.
Abstract: In patients with normal plasmatic coagulation and bleeding tendency, platelet function defect can be assumed. Congenital platelet function defects are rare. Much more commonly they are acquired. The clinical bleeding tendency of platelet function defects is heterogeneous, which makes diagnostic approaches difficult. During the years, a large variety of tests for morphological phenotyping and functional analysis have been developed. The diagnosis of platelet function defects is based on standardized bleeding assessment tools followed by a profound morphological evaluation of the platelets. Platelet function assays like light transmission aggregation, luminoaggregometry, and impedance aggregometry followed by flow cytometry are commonly used to establish the diagnosis in these patients. Nevertheless, despite great efforts, standardization of these tests is poor and in most cases, quality control is lacking. In addition, these tests are still limited to specialized laboratories. This review summarizes the approaches to morphologic phenotyping and platelet testing in patients with suspected platelet dysfunction, beginning with a standardized bleeding score and ending with flow cytometry testing. The diagnosis of a functional defect requires a good collaboration between the laboratory and the clinician.
3 citations
TL;DR: Currently available laboratory tools for diagnosing IPDs with the characteristic laboratory features of each IPD are reviewed, and a general diagnostic approach for the evaluation of IPD patients is presented.
Abstract: Inherited platelet disorders (IPDs) can cause mucocutaneous bleeding due to impaired primary hemostatic function of platelets, thrombocytopenia, or both. Recent advances in molecular technology can help identify many genes related to platelet biology, control the overall steps of megakaryopoiesis, and cause IPD. In this article, currently available laboratory tools for diagnosing IPDs with the characteristic laboratory features of each IPD are reviewed, and a general diagnostic approach for the evaluation of IPD patients is presented.
2 citations
TL;DR: Current methods for the diagnostic assessment of platelet function are reviewed, with a focus on contemporary, best diagnostic laboratory practices, and relationships between clinical and laboratory findings.
Abstract: Abstract Inherited platelet disorders are important conditions that often manifest with bleeding. These disorders have heterogeneous underlying pathologies. Some are syndromic disorders with non-blood phenotypic features, and others are associated with an increased predisposition to developing myelodysplasia and leukemia. Platelet disorders can present with thrombocytopenia, defects in platelet function, or both. As the underlying pathogenesis of inherited thrombocytopenias and platelet function disorders are quite diverse, their evaluation requires a thorough clinical assessment and specialized diagnostic tests, that often challenge diagnostic laboratories. At present, many of the commonly encountered, non-syndromic platelet disorders do not have a defined molecular cause. Nonetheless, significant progress has been made over the past few decades to improve the diagnostic evaluation of inherited platelet disorders, from the assessment of the bleeding history to improved standardization of light transmission aggregometry, which remains a “gold standard” test of platelet function. Some platelet disorder test findings are highly predictive of a bleeding disorder and some show association to symptoms of prolonged bleeding, surgical bleeding, and wound healing problems. Multiple assays can be required to diagnose common and rare platelet disorders, each requiring control of preanalytical, analytical, and post-analytical variables. The laboratory investigations of platelet disorders include evaluations of platelet counts, size, and morphology by light microscopy; assessments for aggregation defects; tests for dense granule deficiency; analyses of granule constituents and their release; platelet protein analysis by immunofluorescent staining or flow cytometry; tests of platelet procoagulant function; evaluations of platelet ultrastructure; high-throughput sequencing and other molecular diagnostic tests. The focus of this article is to review current methods for the diagnostic assessment of platelet function, with a focus on contemporary, best diagnostic laboratory practices, and relationships between clinical and laboratory findings.
2 citations
TL;DR: In this article , the authors performed MS-based proteome profiling on platelets of 34 patients with hereditary platelet disorders (IPDs) with variants in 13 ISTH TIER1 genes that affect different stages of platelet development.
2 citations
TL;DR: In the last years, next-generation sequencing had a great impact on unrevealing the underlying genetic cause of individual IPDs as discussed by the authors , and a comprehensive analysis of platelet function and genetic testing is indispensable.
Abstract: Abstract Platelets play an important role regarding coagulation by contributing to thrombus formation by platelet adhesion, aggregation, and α-/δ-granule secretion. Inherited platelet disorders (IPDs) are a very heterogeneous group of disorders that are phenotypically and biochemically diverse. Platelet dysfunction (thrombocytopathy) can be accompanied by a reduction in the number of thrombocytes (thrombocytopenia). The extent of the bleeding tendency can vary greatly. Symptoms comprise mucocutaneous bleeding (petechiae, gastrointestinal bleeding and/or menorrhagia, epistaxis) and increased hematoma tendency. Life-threatening bleeding can occur after trauma or surgery. In the last years, next-generation sequencing had a great impact on unrevealing the underlying genetic cause of individual IPDs. Because IPDs are so diverse, a comprehensive analysis of platelet function and genetic testing is indispensable.
1 citations
TL;DR: PACT is a useful modality for the diagnosis of PFD, especially in children, thrombocytopenia cases or in the setup where an aggregometer is not readily available, and is stable up to 24 hours in samples stored/transported at 2–8◦C.
Abstract: Abstract Light transmission aggregometry (LTA) is the gold standard for the diagnosis of platelet function disorders (PFDs). The requirement of customized aggregometer, large blood volume, normal platelet count and processing within 4 hours of venipuncture for LTA makes platelet function testing inaccessible to wider population. Flow cytometric platelet activation test (PACT) may overcome these limitations. This study compares the performance of PACT with LTA, characterizes diagnostic patterns of PFDs on PACT and assesses the stability of PACT beyond 4 hours of venipuncture in controls (n = 5) at different temperature conditions. LTA and PACT were performed in 121 healthy controls and 66 patients with suspected PFD. PACT had excellent agreement (kappa = 0.93) with LTA and 94.1% sensitivity, 98.5% specificity. PACT had distinct patterns in Bernard Soulier Syndrome (n = 10), Glanzmann Thrombasthenia (n = 24), δ-granule disorder (n = 7), and other PFDs (n = 12). PACT could assess platelet function in patients (14%) with thrombocytopenia/lipemia wherein LTA was inconclusive. PACT was stable up to 24 hours in samples stored/transported at 2–8◦C. The results of utility and stability are only valid for the specific markers, agonist concentrations, and conditions investigated in this paper. PACT is a useful modality for the diagnosis of PFD, especially in children, thrombocytopenia cases or in the setup where an aggregometer is not readily available.
1 citations
TL;DR: Aibibula et al. as mentioned in this paper analyzed the proteome of essential thrombocythemia (ET) platelets and characterized their functional properties according to the mutational background and treatment regimens.
Abstract: Background: Essential thrombocythemia (ET) is a heterogeneous disease subdivided into five genetic groups according to WHO, based on the common MPN driver mutations (JAK2 V617F, MPL W515K/L, and CALR Type I&II). Current treatment strategies include anti-platelet (e.g. acetylsalicylic acid (ASA)) or cytoreductive agents (e.g. hydrea (HU)) and target mainly complications related to platelet dysfunction (i.e. hemorrhage/thrombosis). Platelet activation is an energy demanding process fueled mainly by a dynamic equilibrium between mitochondria oxidative phosphorylation and glycolysis1. Importantly, altering the platelet catabolic response to activation has been shown to prevent thrombus formation2. JAK2 V617F platelets have been reported to be more activated than CALR mutated platelets3, as well as JAK2 mutated patients have a greater thrombotic risk in comparison to other ET groups. However, the cause of this phenotype is not completely understood. Aims: In this study we aimed to analyze the proteome of ET platelets and to characterize their functional properties according to the mutational background and treatment regimens. Methods: 22 healthy donors (HD) and 67 ET patients have been included in the study. Most of the patients were treated with low dose aspirin (ASA), anagrelide (ANA) or hydrea (HU) or a combination of these. Specifically, 35 out of the 67 ET platelet samples and 8 out of 22 HD were subjected to label-free quantitation mass spectrometry (LFQ-MS). All HD and ET platelets were also analyzed for surface marker expression, degranulation and aggregation capacity by flow cytometry. Results: Hierarchical clustering of the mass spectrometry data revealed different proteomic profiles between HD and ET mutational groups and specifically between JAK2 V617F and CALR I and CALR Type II treated and/or untreated platelets. In general, HD platelets were more enriched for proteins related to platelet activation, and degranulation as compared to ET platelets and clustered next to JAK2 V617F ASA-treated platelet samples (Figure 1). In particular, the JAK2 V617F ASA-treated platelets presented significant enrichment in platelet activation metabolic and mitochondrial proteins in contrast to the CALR Type I and Type II ET platelets. Of note, no peptides corresponding to the mutant CALR were detected using label-free MS methods. Surface marker expression was variable among ET patients. However, CD49B and CD36 surface markers were the most affected among the JAK2V617F and CALR Type I and II platelets and their levels (mean fluorescence intensity-MFI-) were inversely correlated. With regards to platelet aggregation, JAK2 V617F platelets presented similar or lower levels when compared to HD platelets, in line with their proteomic profiles. Differences in aggregation and degranulation levels were also observed between CALR Type I and Type II platelets specifically in the untreated condition. Image:Summary/Conclusion: ET platelets are functional but they show different capacities to respond upon various stimuli and treatment regimens. JAK2 V61F platelets are more activated than any other ET group according to their proteome profile, which is not fully reflected by the functional assays. Mitochondrial activity arises as an important factor in the control of platelet reactivity and it could be critical in disease management and treatment strategies, specifically for the JAK2 V617F patients. References 1. Aibibula, M., et al. J Thromb Haemost. 2018; 16(11):2300-2314, 2. Nayak, M.K., et al. Blood Adv. 2018; 2(15):2029-2038, 3. Hauschner, H., et al. Am J Hematol, 2020. 95(4): p. 379-386.
TL;DR: A study where highthroughput exome sequencing and genomic bioinformatics analysis identified patients homozygous for two known and six novel variants in the RAS guanylreleasing protein 2 gene (RASGRP2) highlights the utility of modern genetic analysis in the diagnosis of patients suspected of having an inherited platelet disorder, particularly when platelet counts and morphology appear normal.
Abstract: In this issue of the British Journal of Haematology, Kawankar et al. report the results of a study where highthroughput exome sequencing and genomic bioinformatics analysis identified patients homozygous for two known and six novel variants in the RAS guanylreleasing protein 2 gene (RASGRP2). The cohort of mostly young Indian patients shared a history of mucosal bleeding, normal coagulation test results and platelet counts, and markedly depressed platelet response to adenosine diphosphate (ADP) and collagen under light transmission aggregometry (LTA). These findings parallel those of Canault et al. in 2014, which reported severe earlyonset bleeding in siblings homozygous for the c.G742T RASGRP2 variant, resulting in a p.G248W alteration from wildtype in RASGRP2, also known as calcium and diacylglycerolregulated guanine nucleotide exchange factor I (CalDAGGEFI). Subsequent studies identified patients with similar symptoms who were homozygous 5 or compound heterozygous for rare variants in RASGRP2. The LTA results from these patients parallel Glanzmann thrombasthenia (GT), where platelets have quantitative or qualitative deficiencies of the fibrinogen receptor, αIIbβ3, an integrin encoded by the ITGA2B and ITGB3 genes. Thus, it is not surprising that GT was the initial clinical diagnosis for several patients subsequently revealed to harbour rare variants in RASGRP2. This highlights the utility of modern genetic analysis in the diagnosis of patients suspected of having an inherited platelet disorder, particularly when platelet counts and morphology appear normal. Studies of RASGRP2 expression and function preceded the linking of this protein to human bleeding problems, as covered in a recent comprehensive review. Canonical RASGRP2 is a 609 amino acid protein (~69 kDa) expressed in several haematopoietic cell lineages, including platelets and precursor megakaryocytes. Like other members of its protein family RASGRP2 is a guanine exchange factor (GEF), although unlike other RASGRPs it exclusively activates Rap GTPases — the most abundant in the platelet lineage being functionally redundant Rap1A and Rap1B. Studies of RASGRP2 function in platelets have relied on Rasgrp2 mice, and revealed essential roles of this protein in several signalling pathways involved in the platelet activation response, including integrinmediated ‘insideout’ activation. The relevance of Rasgrp2 mice as a model for human RASGRP2 deficiency is strong, because studies where expression levels were examined have reported greatly reduced or absent platelet RASGRP2 in patients homozygous for c.914G>A (p.G305D), c.706C>T (p.Q236X), c.887G>A (p.C296Y), c.1142C>T (p.S321F) and c.337C>T (p.R113X), and also for those compound heterozygous for c.1178A>T (p.K360X) and c.1331_1333delCTG (p.L360del). Other reported variants are predicted to yield little or no functional protein, such as c.163A>T (p.L55X). However, as might be expected for a protein with multiple effects, not all pathogenic RASGRP2 variants depress expression. Notably, Canault et al. reported normal levels of RASGRP2 mRNA and protein in platelets from patients homozygous for the c.G742T (p.G248W) variant. Their Received: 21 January 2022 | Accepted: 24 January 2022
TL;DR:
Abstract: Abstract: This paper discusses features of the course and measures for the correction of thrombocytopathy in adolescents. Thrombocytopathy is a chronic disorder of normal hemostasis, in which the number of formed cells (platelets) remains at an acceptable level, but their functionality decreases significantly, which leads to a catastrophe on the part of the entire hematopoietic system
TL;DR: In this article , the authors reported that platelet function disorder in the presence of normal platelet count has been reported to lead to variable clinical phenotypes, and different diagnosis of these bleeding diathesis types has been much more complex than thrombocytopenic bleeding dathesis conditions.
Abstract: Platelet function disorder in the presence of normal platelet count has been reported to lead to variable clinical phenotypes [1]. Differential diagnosis of these bleeding diathesis types has been much more complex than thrombocytopenic bleeding diathesis conditions.