Multicenter evaluation of light transmission platelet aggregation reagents: communication from the ISTH SSC Subcommittee on Platelet Physiology.

BACKGROUND: Light transmission aggregation (LTA) is used widely by the clinical and research communities. Although it is a gold standard, there is a lack of interlaboratory harmonization. OBJECTIVES: The primary objective was to assess whether sources of activators (mainly adenosine diphosphate [ADP], collagen, arachidonic acid, epinephrine, and thrombin receptor activating peptide6) and ristocetin contribute to poor LTA reproducibility. The secondary objective was to evaluate interindividual variability of results to appreciate the distribution of normal values and consequently better interpret pathologic results. METHODS: An international multicenter study involving 28 laboratories in which we compared LTA results obtained with center-specific activators and a comparator that we supplied. RESULTS: We report variability in the potency (P) of activators in comparison with the comparator. Thrombin receptor activating peptide 6 (P, 1.32-2.68), arachidonic acid (P, 0.87-1.43), and epinephrine (P, 0.97-1.34) showed the greatest variability. ADP (P, 1.04-1.20) and ristocetin (P, 0.98-1.07) were the most consistent. The data highlighted clear interindividual variability, notably for ADP and epinephrine. Four profiles of responses were observed with ADP from high-responders, intermediate-responders, and low-responders. A fifth profile corresponding to nonresponders (5% of the individuals) was observed with epinephrine. CONCLUSION: Based on these data, the establishment and adoption of simple standardization principles should mitigate variability due to activator sources. The observation of huge interindividual variability for certain concentrations of activators should lead to a cautious interpretation before reporting a result as abnormal. Confidence can be taken from the fact that difference between sources is not exacerbated in patients treated with antiplatelet agents.

Pancytopenia in a patient treated with fusidic acid and niraparib: a case report.

Fusidic acid is an antibiotic used in the treatment of staphylococcal infections. Niraparib is an anticancer drug indicated for the treatment of advanced ovarian cancer. The interaction between these two drugs has not been studied and is not referenced in drug databases. We present the case of a patient with pancytopenia who had been treated with fusidic acid and niraparib. No other treatment was taken by this patient. According to the literature, both substances can cause haematological toxicity. It seems unlikely that this is due to niraparib alone because it had been well tolerated by the patient for over a year before the pancytopenia was diagnosed. It was also perfectly well tolerated when it was reintroduced. We cannot determine whether this pancytopenia is due to fusidic acid alone or to a drug interaction between the two treatments. We therefore recommend caution in patients treated with this combination.

Biomarker variation in patients successfully treated with tocilizumab for severe coronavirus disease 2019 (COVID-19): results of a multidisciplinary collaboration.

OBJECTIVES: Acute respiratory distress syndrome (ARDS) related to SARS-CoV-2 is likely due to a cytokine storm characterised by a major release of pro-inflammatory cytokines, including interleukin-6 (IL-6). Blocking excessive IL-6 production might be the key to the COVID-19-ARDS treatment. Beneficial effects of IL-6 blockade using a humanised anti-IL-6 receptor antibody, tocilizumab (TCZ) were previously reported in patients with COVID-19 related ARDS. The aim of the study was to study the variation over time of several biomarkers, demonstrated to be predictors of poor prognostic, in subjects successfully treated with TCZ for severe COVID-19. METHODS: Retrospective analysis of a case series of patients with COVID-19-ARDS, evidenced by RT-PCR and lung CT-scan. Patients with increasing O2 requirements, within the window of opportunity for TCZ treatment (Day 7 to Day 17 after onset of symptoms) were treated with TCZ (2 infusions of 8 mg/kg). Demographic, biological and clinical data were collected from the patients' files. Serum levels of CRP, ferritin, fibrinogen, lymphocytes, platelets, creatinine, D-dimer and liver enzymes were assayed at the time of the first TCZ administration, then every two days for 8 days. RESULTS: 40 patients were treated with TCZ. Most of them had several comorbidities, and all had multiple biological abnormalities (lymphopenia, increased CRP, ferritin, fibrinogen, D-dimer, liver enzymes). 30 patients (75%) benefited from TCZ and 10 patients died. In the survivors, following TCZ administration CRP decreased dramatically as early as day 4 (-86.7%, p<0.0001) and returned to normal at day 6. Fibrinogen and lymphocyte count returned to normal values at day 6. Ferritin also decreased significantly. No significant change was observed for D-dimer (p=0.68) and other studied biomarkers (haemoglobin, leucocyte count, AST). CONCLUSIONS: In patients with COVID-19 acute respiratory distress syndrome, treatment with TCZ resulted in favourable evolution in 75% of the cases. Biomarkers of inflammation (CRP, ferritin, fibrinogen) decreased dramatically as early as the 4th day after TCZ injection. Lymphopenia, a predictor of poor prognostic, was reversed 6 days after TCZ injection.

Novel ACTN1 variants in cases of thrombocytopenia.

The ACTN1 gene has been implicated in inherited macrothrombocytopenia. To decipher the spectrum of variants and phenotype of ACTN1-related thrombocytopenia, we sequenced the ACTN1 gene in 272 cases of unexplained chronic or familial thrombocytopenia. We identified 15 rare, monoallelic, nonsynonymous and likely pathogenic ACTN1 variants in 20 index cases from 20 unrelated families. Thirty-one family members exhibited thrombocytopenia. Targeted sequencing was carried out on 12 affected relatives, which confirmed presence of the variant. Twenty-eight of 32 cases with monoallelic ACTN1 variants had mild to no bleeding complications. Eleven cases harbored 11 different unreported ACTN1 variants that were monoallelic and likely pathogenic. Nine variants were located in the α-actinin-1 (ACTN1) rod domain and were predicted to hinder dimer formation. These variants displayed a smaller increase in platelet size compared with variants located outside the rod domain. In vitro expression of the new ACTN1 variants induced actin network disorganization and led to increased thickness of actin fibers. These findings expand the repertoire of ACTN1 variants associated with thrombocytopenia and highlight the high frequency of ACTN1-related thrombocytopenia cases. The rod domain, like other ACTN1 functional domains, may be mutated resulting in actin disorganization in vitro and thrombocytopenia with normal platelet size in most cases.

ANKRD26 normocytic thrombocytopenia: a family report.

We report the identification of a new case of familial non syndromic severe thrombocytopenia. Bleeding was mild and no extra-haematological symptoms were found. Platelet morphology was normal as well as the quantitative expression of platelet membrane glycoproteins. Platelet functions could not be studied due to the intensity of the thrombocytopenia. Molecular analysis identified a mutation located in the promoter of the ankyrin repeat domain 26 (ANKRD26) gene, c.-127A>T, recently reported to be responsible of normocytic thrombocytopenia, but also of a possible increased risk of leukemia/myelodysplasia. Actual knowledge on this new type of inherited thrombocytopenia is also presented.

Mutation spectrum and genotype-phenotype correlations in a large French cohort of MYH9-Related Disorders.

MYH9-Related Disorders are a group of rare autosomal dominant platelet disorders presenting as nonsyndromic forms characterized by macrothrombocytopenia with giant platelets and leukocyte inclusion bodies or as syndromic forms combining these hematological features with deafness and/or nephropathy and/or cataracts. They are caused by mutations in the MYH9 gene encoding the nonmuscle myosin heavy chain II-A (NMMHC-IIA). Until now, at least 49 MYH9 mutations have been reported in isolated cases or small series but only rarely in large series. We report the results of an 8-year study of a large cohort of 109 patients from 37 sporadic cases and 39 unrelated families. We have identified 43 genetic variants, 21 of which are novel to our patients. A majority, 33 (76.7%), were missense mutations and six exons were preferentially targeted, as previously published. The other alterations were three deletions of one nucleotide, one larger deletion of 21 nucleotides, and one duplication. For the first time, a substitution T>A was found in the donor splice site of intron 40 (c.5765+2T>A). Seven patients, four from the same family, had two genetic variants. The analysis of the genotype-phenotype relationships enabled us to improve the knowledge of this heterogeneous but important rare disease.

Spectrum of the mutations in Bernard-Soulier syndrome.

Bernard-Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder characterized by defects of the GPIb-IX-V complex, a platelet receptor for von Willebrand factor (VWF). Most of the mutations identified in the genes encoding for the GP1BA (GPIbα), GP1BB (GPIbß), and GP9 (GPIX) subunits prevent expression of the complex at the platelet membrane or more rarely its interaction with VWF. As a consequence, platelets are unable to adhere to the vascular subendothelium and agglutinate in response to ristocetin. In order to collect information on BSS patients, we established an International Consortium for the study of BSS, allowing us to enrol and genotype 132 families (56 previously unreported). With 79 additional families for which molecular data were gleaned from the literature, the 211 families characterized so far have mutations in the GP1BA (28%), GP1BB (28%), or GP9 (44%) genes. There is a wide spectrum of mutations with 112 different variants, including 22 novel alterations. Consistent with the rarity of the disease, 85% of the probands carry homozygous mutations with evidence of founder effects in some geographical areas. This overview provides the first global picture of the molecular basis of BSS and will lead to improve patient diagnosis and management.

Analysis of 339 pregnancies in 181 women with 13 different forms of inherited thrombocytopenia.

Pregnancy in women with inherited thrombocytopenias is a major matter of concern as both the mothers and the newborns are potentially at risk of bleeding. However, medical management of this condition cannot be based on evidence because of the lack of consistent information in the literature. To advance knowledge on this matter, we performed a multicentric, retrospective study evaluating 339 pregnancies in 181 women with 13 different forms of inherited thrombocytopenia. Neither the degree of thrombocytopenia nor the severity of bleeding tendency worsened during pregnancy and the course of pregnancy did not differ from that of healthy subjects in terms of miscarriages, fetal bleeding and pre-term births. The degree of thrombocytopenia in the babies was similar to that in the mother. Only 7 of 156 affected newborns had delivery-related bleeding, but 2 of them died of cerebral hemorrhage. The frequency of delivery-related maternal bleeding ranged from 6.8% to 14.2% depending on the definition of abnormal blood loss, suggesting that the risk of abnormal blood loss was increased with respect to the general population. However, no mother died or had to undergo hysterectomy to arrest bleeding. The search for parameters predicting delivery-related bleeding in the mother suggested that hemorrhages requiring blood transfusion were more frequent in women with history of severe bleedings before pregnancy and with platelet count at delivery below 50 × 10(9)/L.

[Usefulness of gray platelets observation in ARC syndrome]. / ARC syndrome et observation de plaquettes grises: utilité diagnostique.

Arthrogryposis Renal Fanconi syndrome and Cholestasis (ARC syndrome) is an extremely rare disease (62 cases) and is uneasy to diagnose. This congenital multisystem disorder affects newborns who usually die in the first year of life. The three cases here report the main clinical and biological features of this unknown disease and show how careful platelets morphology examination on blood smear can help for diagnosis. The three cases were observed at Robert Debré hospital in Paris over a twenty years period. In the first case, ARC syndrome was diagnosed after death. For the two following newborns, gray platelets detection in association with clinical symptoms allowed an earlier diagnosis.

Acute renal cortical necrosis due to acquired antiprotein S antibodies.

Although varicella is a common disease of childhood, renal complications are quite rare. We report here the interesting case of a-22 month-old boy exhibiting renal cortical necrosis related to an acquired protein S deficiency following varicella. Ten days after the vesicle eruption appearance, he presented with ecchymosed heels, oligoanuric kidney failure, anemia [hemoglobin (Hb) 78 g/L], schizocytosis (2.5%), but normal platelet count. Kidney sonography and magnetic resonance imaging evoked renal cortical necrosis. All together, these features suggested acquired protein S deficiency secondary to varicella. Strikingly, it was confirmed by a dramatic decrease in protein S plasma activity and a huge increase in immunoglobulin (Ig)G antibodies against protein S in the plasma. Anticoagulation therapy in addition with plasmapheresis and steroid pulses allowed a dramatic decrease in the antibodies against protein S and recovery of normal protein S activity. Undelayed diagnosis and treatment did not avoid kidney insufficiency but prevented life-threatening complications. In the light of this case report, protein S deficiency due to antibody inhibition should be carefully monitored anytime in the context of varicella when kidney insufficiency or necrosis occurs.

Biochemical markers of neonatal sepsis: value of procalcitonin in the emergency setting.

BACKGROUND: We evaluated procalcitonin (PCT) assay in the emergency diagnosis of neonatal bacterial infection, especially in preterm infants, relative to C-reactive protein (CRP) and fibrinogen. METHODS: One hundred and twenty neonates (32 preterm), of whom 21 were infected, were tested. RESULTS: Concentrations of PCT, CRP and fibrinogen in uninfected infants were not affected by gestational age at birth. Concentrations of CRP and PCT increased rapidly during the first 24 h of life, while fibrinogen concentrations increased gradually from birth. All marker concentrations were significantly greater in neonates with bacterial infection. Receiver-operating characterstic analysis showed that optimum cut-off values for fibrinogen, CRP and PCT were 3.0 g/L, 7.5 mg/L and 2.5 microg/L respectively, for the diagnosis of sepsis at birth. CONCLUSIONS: Determination of PCT is of value in excluding bacterial infection in neonates since it has a negative predictive value of 93%.

[Evaluation of the STA-R analyzer for the study of neonatal and pediatric hemostasis].

To evaluate the capacities of adaptation of the STA-R analyzer (Diagnostica Stago, Asnieres, France) to the study of pediatric hemostasis, classical studies were undertaken and they have included: (1) Within-run assays (n = 21, 2 control levels) and day-to-day precision studies (n = 20, 2 control levels) for the following tests: prothrombin time (PT), activated partial thromboplastin time (APTT), factor II (FII), factor VII + X (FVII + X), factor V (FV), fibrinogen (fg) and antithrombin (AT); (2) Comparison of the results of APTT, FII, FVII + X, FV and fg assays (in 50 plasmas) obtained with STA-R and STA (analyzer currently used, in our pediatric laboratory). Specific pediatric evaluation has included: (1) Evaluation of the STA-R results for low concentrations of the coagulation factors; (2) Determination of the lowest dead volume; (3) Introduction of peculiar samples among "routine" series. The results showed that within-run assays and day-to-day precision studies have confirmed the good performances of the STA-R. The comparison of the STA-R and STA results from 50 plasmas shows a correlation coefficient of 0.990, 0.995, 0.996, 0.997 and 0.996 for APTT, fg, FII, FVII + V and FV respectively. Such results are confirmed for low concentrations of coagulation factors. The acceptable dead volume could be lowered down to 50 microliters. Very small samples, selected assays and emergencies could be easily introduced among routine series. It is concluded that the STA-R showed very good technical performances. The STA-R is adapted to the routine tests as well as to the very specific samples of neonates and children.