Frequency, clinical, and laboratory findings of platelet secretion disorders in patients referred to the specialized coagulation laboratory of the Iranian Blood Transfusion Organization

OBJECTIVES

Platelet secretion disorders (PSDs) are a subgroup of platelet function disorders (PFDs) caused by defects in the content or release of platelet granules. These patients have a variable degree of mucocutaneous bleeding tendency. The diagnostic facilities of PSDs are imitated in Iran, even in specialized coagulation laboratories. The present study aims to estimate the frequency of PSDs among patients referred to the Iranian Blood Transfusion Organization (IBTO).

METHODS

The research population includes all patients referred to the specialized coagulation laboratory of IBTO and requested platelet function and von Willebrand testing by their physicians. They were recruited between May 2022 and October 2022 if they were not diagnosed as having procoagulant defects, von Willebrand disease (VWD), Glanzmann thrombasthenia (GT), Bernard-Soulier syndrome (BSS), and platelet count <100 × 10 9 (except in the syndromic forms). Patients with a defect in response to at least two agonists in Light transmission aggregometry (LTA), one agonist in the ATP-secretion study, and/or impairment in the expression of CD62P are considered PSDs.

RESULTS

Among 121 cases referred to our center over 6 months, 40 patients fulfilled the inclusion and exclusion criteria. Ten patients were diagnosed with PSDs. Six were classified as δ-platelet secretion disorders (δ-PSD), two α-platelet secretion disorders (α-PSD), and two αδ-platelet secretion disorders (αδ-PSD).

CONCLUSIONS

The prevalence of PSDs in our population study was 25% (10/40), which seems highly prevalent. Therefore, expanding laboratory approaches to platelet function defects is necessary as a routine in our country.

Bleeding disorders in Saudi Arabia, causes and prevalence: a review

As bleeding disorders are a worldwide health concern, Saudi Arabia is experiencing a notable prevalence of such disorders. Studying the frequency and cause of hemostatic disorders is the key to successful clinical interventions and instigating effective public policies that limit the spread of such disorders. The current review aims to highlight the major findings of the body of literature that has investigated the causes, prevalence, and major challenges associated with bleeding disorders in the country. The current review summarizes the major findings of different studies that have been conducted in Saudi Arabia regarding different bleeding disorders. Multiple causes and symptoms of bleeding disorders have been reported by different studies. Some studies investigated the genetic aspect of bleeding disorders and revealed specific mutations in coagulation factor genes influencing the symptoms of different bleeding disorders. Moreover, rare bleeding disorders such as Glanzmann thrombasthenia and Henoch-Schönlein purpura, have been reported in different regions of Saudi Arabia. Combining clinical presentations, genetic factors, and epidemiological data, the current review of the literature provides a comprehensive insight into bleeding disorders in the kingdom. This will help in advancing the diagnostic capabilities and genetic counseling enhancing management strategies and therapeutic interventions benefiting bleeding disorder patients and the kingdom.

Utility of the international society on thrombosis and hemostasis-bleeding assessment tool in the diagnosis of patients who suspected of platelet function disorders

The ISTH-BAT is a structured bleeding assessment tool to record and help diagnose patients with possible bleeding disorders. However, a few studies evaluated the utility of ISTH-BAT in diagnosing patients with platelet function defects (PFDs). In this study, we evaluated the diagnostic utility of ISTH-BAT in predicting PFDs among patients suspected of PFDs. Forty patients suspected of PFDs and 21 normal healthy controls were evaluated by the ISTH-BAT scoring system, light transmission aggregometry (LTA), ATP-releasing assays (lumi-aggregometry), and expression of CD62P for diagnosis of PFDs. Among 40 patients suspected of PFDs, 10 were diagnosed as PFDs using lumiaggregometry and CD62P. The ISTH-BAT score in patients suspected of PFDs [(6, interquartile range (IQR) 1-8] and patients with PFDs was significantly higher than the control group (0; IQR 0-0) ( P  < 0.001). Receiver operating characteristic curves indicate that ISTH-BAT is not able to discriminate patients with PFDs from those without PFDs (areas under the curve of 0.620 (95% confidence interval 0.415-0.825). The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the ISTH-BAT in predicting the presence of PFDs, respectively, were 40, 73.3, 33.3, and 78.6% in the cut-off ISTH-BAT at least 4 in adult men, at least 6 in adult women, and at least 3 in children (age < 18). The ISTH-BAT scoring system has good discriminatory power in diagnosing patients with PFDs from healthy controls but is ineffective in differentiating them from those without PFDs.

Expert opinion on the use of platelet secretion assay for the diagnosis of inherited platelet function disorders: Communication from the ISTH SSC Subcommittee on Platelet Physiology

Assessment of platelet secretion is crucial for diagnosing suspected inherited platelet function disorders (IPFD). A previous survey of the SSC on Platelet Physiology of the ISTH and a comprehensive review highlighted that most of the platelet secretion assays (PSAs) lack standardization and validation. The aim of this study was to provide expert consensus guidance on the use of PSAs for IPFD diagnosis. We surveyed 26 experts from 10 different countries using the RAND/UCLA methodology, to attain a consensus on sensitivity, specificity, feasibility, time to readout, and cost of most PSAs. Answers were then graded in three categories: appropriate, uncertain, and inappropriate. Equivocal or misinterpretable statements required a second and third round survey involving 14 of the original 26 experts. We report here the consolidated results of the entire procedure. There was uniform agreement on several general statements, including that PSAs should be performed in hemostasis laboratories as first line diagnostic tests even in patients with normal platelet aggregation, and should include a δ-granule secretion marker. Among the specific assays examined, lumiaggregometry, other luciferin/luciferase-based assays, high-performance liquid chromatography methods, radiolabeled-serotonin based assays, and whole-mount transmission electron microscopy were rated as appropriate for the measurement of δ-granule release, and platelet P-selectin expression by flow cytometry and released proteins by ELISA for α-granule release. For most of the other PSAs, the expert opinions were widely dispersed. Lack of expert consensus on many PSAs clearly indicates an unmet need for rigorous standardization, multicenter comparison of results, and validation of PSAs for clinical laboratory practice.

A refugee child with multiple patterned ecchymoses: a diagnostic dilemma between nonaccidental injury and primary hemostatic defect

A 4-year-old girl from Syria presented to the hospital with multiple bruises on her body. Bruises were observed in protected areas in a shape of fingerprints and objects, while no other bruises occurred during hospitalization. The parents also reported a history of bleeding diathesis from infancy. Both the initial laboratory evaluation and the secondary tests done for possible thrombocytopenia and coagulation factors deficiencies were normal. Thus, the nonaccidental injury protocol of the Hospital was activated, and the possibility of abuse was not quite evident. Investigation for platelet disorders followed. Platelet aggregation test and flow cytometry were indicative of Glanzmann's thrombasthenia. It is of great importance in these cases, that the doctor eliminates any possibility of physical abuse and examines the patient for common and rare primary hemostatic defects, although both can co-exist.

Acquired Glanzmann thrombasthenia associated with platelet desialylation

BACKGROUND

The notable discrepancy between platelet count and bleeding manifestations in immune thrombocytopenia (ITP) patients with acquired Glanzmann thrombasthenia (GT) has been described.

OBJECTIVES

We aimed to examine the mechanisms responsible for thrombocytopenia and the bleeding phenotype in a patient with acquired GT.

PATIENT, METHODS, AND RESULTS

A patient with primary ITP underwent splenectomy due to steroid intolerance. Despite platelet count normalization, bleeding continued. Platelet aggregometry was abnormal with all agonists except for ristocetin. Flow cytometry demonstrated the presence of antiplatelet antibody, which caused dose-dependent inhibition of fibrinogen and PAC-1 binding, induction of neuraminidase-1 expression as well as platelet desialylation in donor platelets. Indirect monoclonal antibody immobilization of platelet specific antigen assay (MAIPA) confirmed specificity to αIIb β3 only, corroborated by binding on Chinese hamster ovary (CHO) cells expressing human glycoprotein αIIb β3 but not GP Ib/IX. Both desialylation and neuraminidase expression were observed with plasma adsorbed on Ib/IX CHO cells and with the immunoglobulin G (IgG) fraction. Desialylation was inhibited in the presence of anti-Fc-gamma receptor IIa (FcγRIIa) antibody. A nonobese diabetic/severe combined immunodeficient ITP murine model was established, which showed rapid hepatic donor platelet clearance in the presence of patient IgG. Treatment of mice with the neuraminidase inhibitor oseltamivir significantly reduced antibody-induced platelet destruction.

CONCLUSIONS

We report the first case of a patient with acquired GT due to ITP with FcγRIIa mediated platelet desialylation, independent of platelet activation. Treatment with neuraminidase inhibitor may prevent platelet clearance by anti-αIIb β3 antibodies.

[The clinical characteristics and molecular pathogenesis of a variant Glanzmann's thrombasthenia-like pedigree]

Objective: To review the clinical characteristics of a pedigree with inherited hemorrhagic disease to explore its molecular pathogenesis. Methods: The clinical data of the pedigree with inherited hemorrhagic disease were collected. After extracting DNA, next generation sequencing was utilized to detect the potential gene mutation. The changes of RASGRP2 transcript of this proband and his parents were detected using RT-PCR to compare with normal control. Results: The phenotype of the proband in this pedigree with inherited platelet dysfunction and bleeding disorder was similar to variant Glanzmann's thrombasthenia, the maximum aggregations of platelet in response to the physiological agonists including ADP, epinephrine and arachidonic acid were significantly lower, leading to severe spontaneous mucosal bleeding. Integrin αIIbβ3 gene mutation was not detected, but another gene mutation RASGRP2 IVS3-1 stood out. The mutation was homozygous in the proband and heterozygosis in both of his parents. Two transcript types were detected in the proband, without transcripts coding functional RASGRP2 protein, however, his parents had functional transcripts and abnormal transcripts, with the normal transcripts in the majority. Conclusions: The RASGRP2 IVS3-1 gene mutation was responsible for the inherited hemorrhagic disease. The RASGRP2 IVS3-1 gene mutation led to abnormal alternative splicing, without formation of functional RASGRP2 protein. The RASGRP2 protein is at the nexus of calcium-dependent platelet activation and hemostasis after damage of blood vessels. Spontaneous mucosal bleeding was a result of the lack of the functional RASGRP2 protein. This was the first report of RASGRP2 gene mutation resulting in bleeding disorder in China, and also the first report of the mutation type of RASGRP2 IVS3-1.

Impact of an audit program and other factors on door-to-balloon times in acute ST-elevation myocardial infarction patients destined for primary coronary intervention

OBJECTIVES

This before-after study investigated the association between an audit program and door-to-balloon times in patients with acute ST-elevation myocardial infarction (STEMI) and explored other factors associated with the door-to-balloon time.

METHODS

An audit program that collected time data for essential time intervals in acute STEMI was developed with data feedback to both the Department of Emergency Medicine and the Department of Cardiology. The door-to-balloon times for 76 consecutive acute STEMI patients were collected from February 16, 2007, through October 31, 2007, after the implementation of the audit program, as the intervention group. The control group was defined by 104 consecutive acute STEMI patients presenting from April 1, 2006, through February 15, 2007, before the audit was applied. A multivariate linear regression model was used for analysis of factors associated with the door-to-balloon time.

RESULTS

The geometric mean 95% CI of the door-to-balloon time decreased from 164.9 (150.3, 180.9) minutes to 141.9 (127.4, 158.2) minutes (p = 0.039) in the intervention phase. The median door-to-balloon time was 147.5 minutes in the control group and 136.0 minutes in the intervention group (p = 0.09). In the multivariate regression model, the audit program was associated with a shortening of the door-to-balloon time by 35.5 minutes (160.4 minutes vs. 195.9 minutes, p = 0.004); female gender was associated with a mean delay of 58.4 minutes (208.9 minutes vs. 150.5 minutes; p = 0.001); posterolateral wall infarction was associated with a mean delay of 70.5 minutes compared to anterior wall infarction (215.4 minutes vs. 144.9 minutes; p = 0.037) and a mean delay of 69.5 minutes compared to inferior wall infarction (215.4 minutes vs. 145.9 minutes; p = 0.044). The use of a glycoprotein IIb/IIIa inhibitor was associated with a 46.1 minutes mean shortening of door-to-balloon time (155.7 minutes vs. 201.8 minutes; p < 0.001).

CONCLUSIONS

The implementation of an audit program was associated with a significant reduction in door-to-balloon times among patients with acute STEMI. In addition, female patients, posterolateral wall infarction territory, and nonuse of glycoprotein IIb/IIIa inhibitor were associated with longer door-to-balloon times.

[Application of rFVIIa for controlling acute bleeding in the obstetric and gynecologic practice]

We present four cases, 3 in the obstetrics with and without coagulation disorders and a case in gynecology with Glanzmann Thrombasthenia and the application of rFVIIa when acute hemorrhage occurred. We achieved fast and definitive hemostasis in cases with life threatening bleeding. rFVIIa helps to decrease the bleeding in order to achieve better surgical haemostasis.

Insights and questions arising from studies of a mouse model of Glanzmann thrombasthenia

In summary, studies of beta 3-deficient mice demonstrate that they provide an excellent model of the human bleeding disorder, Glanzmann thrombasthenia (GT), and replicate essentially all features of the human disease. Furthermore, these mice reveal additional defects consequent upon the absence of integrins alpha v beta 3 and alpha IIB beta 3 that had not become evident from studies of the human patients. These include defects in placental development and in bone resorption. In contrast, despite published evidence suggesting a role for alpha v beta 3 in angiogenesis, beta 3-null mice have not yet shown any defects in this process. The availability of these mice will allow extensive further studies of GT pathogenesis and therapy and of the roles of beta 3 integrins in different forms of angiogenesis, including the pathologically important angiogenic processes in the retina and in response to tumors. Furthermore, they open the way to studies of a variety of other processes in which roles for beta 3 integrins have been suggested.

A Glanzmann thrombasthenia-like phenotype caused by a defect in inside-out signaling through the integrin alpha(IIb)beta3

Activation of the platelet integrin alpha(IIb)beta3, an essential step in platelet aggregation, is regulated by intracellular signal pathways (inside-out signaling). In this study, we characterize a 35-year-old Japanese female, HM, with a life-long history of mucocutaneous bleeding. HM showed a Glanzmann thrombasthenia-like phenotype with normal expression of alpha(IIb)beta3, and failure of platelet aggregation induced by various agonists. An activation-independent ligand mimic monoclonal antibody (mAb), OP-G2, and RGDS peptides bound normally to the patient's alpha(IIb)beta3, while an activating anti-beta3 mAb, AP5, induced normal aggregation of HM platelets. The nucleotide sequence of the entire coding region of the patient's alphaIIb and beta3, including the cytoplasmic domains of each subunit, revealed no abnormalities. Agonist-induced phosphorylation of platelet pleckstrin and myosin light chain was not impaired. Recently, we proposed that a Na+/Ca2+ exchanger is involved in inside-out signaling, especially in the case of chymotrypsin-induced alpha(IIb)beta3 activation (Blood 88: 2594, 1996). However, chymotrypsin-induced platelet aggregation occurred normally in patient HM. Measurement of changes in cytosolic free calcium concentration ([Ca2+]i) revealed that the plateau level of [Ca2+]i after thrombin stimulation was significantly inhibited in patient HM. Our data suggest that patient HM exhibits a Glanzmann thrombasthenia-like phenotype associated with an abnormality in inside-out signaling which would otherwise activate alpha(IIb)beta3.

Glanzmann's thrombasthenia: the use of autologous fibrin glue in tooth extractions

Three teeth were extracted in three sessions in a 15-year-old girl with Glanzmann's thrombasthenia who suffered in the past severe bleeding and required platelet transfusions. The extraction sites were treated locally with autologous fibrin glue in adjunct of tranexamic acid swish and swallow rinses. No systemic platelet infusion was employed as a preventive measure. No postoperative bleeding occurred.