Good engraftment after reduced intensity targeted busulfan-based conditioning and matched related donor hematopoietic cell transplantation in hemoglobinopathies.

BACKGROUND: Hematopoietic cell transplantation (HCT) is an established curative therapy for transfusion-dependent thalassemia (TDT) and sickle cell disease (SCD). The latest American Society of Hematology guidelines recommend myeloablative preparative regimen in patients under 18 years of age. PROCEDURE: The objective was to demonstrate safety and efficacy of a reduced intensity conditioning (RIC) regimen including high-dose fludarabine, anti-thymocyte globulin, and targeted busulfan as a single alkylator to sub-myeloablative exposures. RESULTS: Between 2012 and 2021, 11 patients with SCD and five patients with TDT and matched related donor (MRD) HCT were included. The median age at transplantation was 8.3 years (range: 3.7-18.8 years). The median administered busulfan AUC was 67.4 mg/L×h (range: 60.7-80 mg/L×h). Overall survival was 93.8% and event-free survival 87.5% with one engrafted SCD patient with pre-existing moyamoya disease succumbing after drainage of a subdural hematoma. One SCD patient developed a secondary graft failure and was treated with a second HCT. Myeloid chimerism was full in all other patients with a median follow-up time of 4.1 years (range: 2.0-11.1 years), whereas T-cell donor chimerism was frequently mixed. CONCLUSION: This RIC conditioning followed by MRD HCT is sufficiently myeloablative to cure pediatric patients with hemoglobinopathies without the need for additional total body irradiation or thiotepa.

IVIg treatment increases thrombin activation of platelets and thrombin generation in paediatric patients with immune thrombocytopenia.

Clinical manifestations and laboratory parameters of haemostasis were investigated in 23 children with newly diagnosed immune thrombocytopenia (ITP) before and after intravenous immunoglobulin (IVIg) treatment. ITP patients with platelet counts of less than 20 × 109 /L and mild bleeding symptoms, graded by a standardized bleeding score (BS), were compared with healthy children with normal platelet counts and children with chemotherapy-related thrombocytopenia. Markers of platelet activation and platelet apoptosis in the absence and presence of platelet activators were analysed by flow cytometry; thrombin generation in plasma was determined. ITP patients at diagnosis presented with increased proportions of platelets expressing CD62P and CD63 and activated caspases, and with decreased thrombin generation. Thrombin-induced activation of platelets was reduced in ITP compared with controls, while increased proportions of platelets with activated caspases were observed. Children with a higher BS had lower proportions of CD62P-expressing platelets compared with those with a lower BS. IVIg treatment increased the number of reticulated platelets, the platelet count to more than 20 × 109 /L and improved bleeding in all patients. Decreased thrombin-induced platelet activation, as well as thrombin generation, were ameliorated. Our results indicate that IVIg treatment helps to counteract diminished platelet function and coagulation in children with newly diagnosed ITP.

Using the hemolysis index of Abbott's Alinity c for the measurement of plasma free hemoglobin in ECMO patients.

OBJECTIVES: Quantitative measurement of plasma free hemoglobin (fHb) concentrations is essential for monitoring pediatric ECMO patients, since hemolysis has a great impact on the patient's clinical outcome. The aim of this study was to validate the hemolysis index (HI) assay on Abbott's Alinity c system as a quantitative method to measure fHb. METHODS: The performance of the HI assay, based on an automated spectrophotometric method recording the absorption at four different wavelength pairs, was evaluated using the 20 × 2 × 2 design according to the CLSI-EP05-A3 guidelines. LLOQ and LLOD were calculated according to CLSI-EP17 guidelines with CVs set to 10% and 20%, respectively. Furthermore, the method was tested for interferences with bilirubin and Intralipid®. RESULTS: Linearity was ensured over an analytical measurement range of 30-7250 mg/L and the calculated LLOQ and LLOD were 80 mg/L and 50 mg/L, respectively. Intra-run and total imprecisions ranged from 0.9-3.4% and 1.0-3.4%, respectively. The HI assay correlated well with the Harboe method (HI (mg/L) = 0.998 * fHb (mg/L) + 28 mg/L, R = 0.998, n = 50) and interference testing showed no impact of bilirubin and Intralipid® up to 709 mg/L and 5580 mg/L, respectively. CONCLUSIONS: The HI assay on Abbott's Alinity c system allows a precise and accurate determination of fHb concentrations with no significant interferences in a simple, rapid and cost-effective way.

Clinical evolution, genetic landscape and trajectories of clonal hematopoiesis in SAMD9/SAMD9L syndromes.

Germline SAMD9 and SAMD9L mutations (SAMD9/9Lmut) predispose to myelodysplastic syndromes (MDS) with propensity for somatic rescue. In this study, we investigated a clinically annotated pediatric MDS cohort (n = 669) to define the prevalence, genetic landscape, phenotype, therapy outcome and clonal architecture of SAMD9/9L syndromes. In consecutively diagnosed MDS, germline SAMD9/9Lmut accounted for 8% and were mutually exclusive with GATA2 mutations present in 7% of the cohort. Among SAMD9/9Lmut cases, refractory cytopenia was the most prevalent MDS subtype (90%); acquired monosomy 7 was present in 38%; constitutional abnormalities were noted in 57%; and immune dysfunction was present in 28%. The clinical outcome was independent of germline mutations. In total, 67 patients had 58 distinct germline SAMD9/9Lmut clustering to protein middle regions. Despite inconclusive in silico prediction, 94% of SAMD9/9Lmut suppressed HEK293 cell growth, and mutations expressed in CD34+ cells induced overt cell death. Furthermore, we found that 61% of SAMD9/9Lmut patients underwent somatic genetic rescue (SGR) resulting in clonal hematopoiesis, of which 95% was maladaptive (monosomy 7 ± cancer mutations), and 51% had adaptive nature (revertant UPD7q, somatic SAMD9/9Lmut). Finally, bone marrow single-cell DNA sequencing revealed multiple competing SGR events in individual patients. Our findings demonstrate that SGR is common in SAMD9/9Lmut MDS and exemplify the exceptional plasticity of hematopoiesis in children.

Comparison between intraoperative bleeding score and ROTEM® measurements to assess coagulopathy during major pediatric surgery.

PURPOSE: Intraoperative bleeding should be regularly assessed visually to guide coagulation management. Whereas viscoelastic testing with ROTEM® measurement has been proven to be useful in detecting coagulopathies, the visual assessment is not standardized. This study therefore aims to compare a standardized visual assessment with ROTEM® results. METHODS: A 5-point bleeding score was created and applied in a recently published randomized controlled trial in major pediatric non-cardiac surgery. This score assesses overall bleeding tendency and the occurrence of diffuse bleeding, aqueous bleeding, bleeding outside the operative field, and the ability to control bleeding. Validity of this score was tested by post hoc comparison to the results of simultaneously performed ROTEM® measurements. RESULTS: Signs of coagulopathic bleeding were assessed at 183 time points. Mild to moderate bleeding intensity was judged at 103 time points, in 42 % abnormal ROTEM® traces were obtained simultaneously. When severe bleeding was scored, abnormal ROTEM values occurred in 58 %, and FIBTEM-values were significantly lower than in the "no bleeding group". Altogether, the correlation between bleeding score and ROTEM® measurements was not significant. CONCLUSIONS: The standardized visual assessment did not correlate well with ROTEM® measurements, suggesting that it is not useful to detect coagulopathy. Trial registry number: ClinicalTrials.gov identifier No. NCT01487837.

The landscape of pediatric Diamond-Blackfan anemia in Switzerland: genotype and phenotype characteristics.

Diamond-Blackfan anemia (DBA) is caused mainly by genetic mutations in large (RPL) or small ribosomal subunit genes (RPS) and presents with macrocytic anemia and congenital malformations. Clinical differences between genotypes are insufficiently understood. The aim of this study was to assess clinical features, treatment strategies, and genotypes in the Swiss pediatric DBA population. We retrospectively reviewed medical charts of pediatric patients with DBA in Switzerland and stratified patients by RPL versus RPS mutations. We report 17 DBA patients in Switzerland who were all genetically investigated. In our cohort, patients showed a wide spectrum of clinical presentations and treatment needs. We found a high proportion of physical malformations (77%) including lower limb (17%) and anorectal (12%) malformations. The two patients with anorectal malformations presented both with antepositioning of the anus needing surgery within the first 15 months of life. One of these patients had sphincteric dysfunction, the other coccygeal agenesis. We found that included patients with an RPL mutation more frequently tended to have physical malformations and a milder anemia compared to patients with an RPS mutation (median hemoglobin at diagnosis 76 g/l versus 22 g/l).Conclusion: We illustrate the wide clinical and genetic spectrum of DBA in Switzerland. Our findings highlight the need to take this diagnosis into consideration in patients with severe anemia but also in patients with mild anemia where malformations are present. Lower limb and anorectal malformation extend the spectrum of DBA-associated malformations. What is Known? • There is a large variation in the phenotype of Diamond-Blackfan Anemia (DBA) and diversity of genetic mutations. • Malformation of the upper limbs, head and face, heart, and genitourinary system is frequently identified. What is New? • Patients with lower limb and anorectal malformations were repetitively found in our cohort enlarging the clinical spectrum of malformations. • We show two patients of the same family with a DBA-like condition where the same RPL17 variant was identified.

Platelets express adaptor proteins of the extrinsic apoptosis pathway and can activate caspase-8.

BACKGROUND: Apoptotic pathways in platelets are important for their survival and function. Platelet apoptosis may be involved in the pathogenesis of immune thrombocytopenia (ITP), an autoimmune-mediated disease. In contrast to the intrinsic apoptosis pathway, not much is known about the extrinsic pathway mechanisms in platelets. OBJECTIVES: To investigate the expression of proteins involved in the extrinsic apoptosis pathway, including the death receptors, adaptor and regulator proteins in human platelets. To determine a possible trigger of the extrinsic apoptosis pathway in platelets. METHODS: To investigate the expression of key markers of the extrinsic pathway we used targeted immunofluorescence and flow cytometry assays. To study their expression and interaction we performed Western blotting and co-immunoprecipitation. Treated platelets with different apoptosis triggers were subjected to flow cytometry. RESULTS: We could identify the protein expression of the pro-apoptotic proteins TRADD (Tumor Necrosis Factor Receptor type 1- Associated DEATH Domain protein), TRAF2/5, (TNF Associated Factor) and DEDAF (Death Effector Domain- Associated Factor), FADD (Fas-Associated protein with death domain) as well as the anti-apoptotic proteins DJ-1 (Deglycase 1) and c-FLIP in human platelets. ABT-737 treatment induced a disruption in the co-localization of DJ-1 with FADD. Platelets treated with ABT-737 showed an activation in caspase-3 and -8. The exposure to TNF (Tumor Necrosis Factor), FasL (Fas ligand), and TWEAK or to plasma derived from ITP patients, did not lead to changes in caspase-3 and -8 activation in platelets. CONCLUSIONS: Human platelets express some proteins of the extrinsic apoptosis pathway which can be modulated only by ABT-737 treatment. However so far, no other apoptosis trigger or interaction with an external receptor have been yet identified.

Synonymous GATA2 mutations result in selective loss of mutated RNA and are common in patients with GATA2 deficiency.

Deficiency of the transcription factor GATA2 is a highly penetrant genetic disorder predisposing to myelodysplastic syndromes (MDS) and immunodeficiency. It has been recognized as the most common cause underlying primary MDS in children. Triggered by the discovery of a recurrent synonymous GATA2 variant, we systematically investigated 911 patients with phenotype of pediatric MDS or cellular deficiencies for the presence of synonymous alterations in GATA2. In total, we identified nine individuals with five heterozygous synonymous mutations: c.351C>G, p.T117T (N = 4); c.649C>T, p.L217L; c.981G>A, p.G327G; c.1023C>T, p.A341A; and c.1416G>A, p.P472P (N = 2). They accounted for 8.2% (9/110) of cases with GATA2 deficiency in our cohort and resulted in selective loss of mutant RNA. While for the hotspot mutation (c.351C>G) a splicing error leading to RNA and protein reduction was identified, severe, likely late stage RNA loss without splicing disruption was found for other mutations. Finally, the synonymous mutations did not alter protein function or stability. In summary, synonymous GATA2 substitutions are a new common cause of GATA2 deficiency. These findings have broad implications for genetic counseling and pathogenic variant discovery in Mendelian disorders.

Increased levels of IL-10 and IL-1Ra counterbalance the proinflammatory cytokine pattern in acute pediatric immune thrombocytopenia.

Immune thrombocytopenia (ITP) is an autoimmune disease which leads to accelerated platelet clearance. We investigated the plasma cytokine, chemokine and growth factor signatures and their clinical significance in pediatric ITP patients during acute, chronic and follow-up stages as well as the effects of intravenous immunoglobulin (IVIg) treatment, by using the Multiplex technology. In acute ITP before and/or after IVIg treatment we found significantly increased plasma levels of the pro- (tumour necrosis factor-α (TNF-α), interleukin IL-15) and anti- (IL-1 receptor antagonist (Ra), IL-10 and the growth factor interferon γ-induced protein (IP-10)) inflammatory cytokines, compared to healthy controls. Except for IL1-Ra, these cytokines decreased to normal levels in chronic patients. In contrast, growth-regulated α protein (GRO) and soluble CD40 ligand (sCD40L), known as platelet-derived molecules, were found to be significantly decreased in acute and increased in chronic ITP patients compared to healthy controls. GRO levels positively correlated with the platelet counts in the follow-up and chronic cohort. Monocyte counts showed a significant positive correlation only with IP-10 levels in acute ITP after IVIg treatment and follow-up patients. Expression levels of mRNAs for macrophage inflammatory protein MIP1-ß, IL-1Ra and GRO determined in peripheral blood mononuclear cells (PBMCs) were significantly reduced in both acute and chronic ITP compared to controls. Our findings suggest that the different clinical presentation of acute and chronic pediatric ITP and to a lesser extent the IVIg treatment effects are characterized overall by a counterbalanced cytokine, chemokine and growth factor pattern response that might exert a pathogenic role in this disease.

Diagnosis and management of iron deficiency in children with or without anemia: consensus recommendations of the SPOG Pediatric Hematology Working Group.

Iron deficiency is the most prevalent nutritional deficiency affecting children and adolescents worldwide. A consistent body of epidemiological data demonstrates an increased incidence of iron deficiency at three timepoints: in the neonatal period, in preschool children, and in adolescents, where it particularly affects females.Conclusion: This narrative review focuses on the most suggestive symptoms of iron deficiency in childhood, describes the diagnostic procedures in situations with or without anemia, and provides Swiss expert-based management recommendations for the pediatric context.What is Known:• Iron deficiency (ID) is one of the most common challenges faced by pediatricians.• Significant progress in the diagnosis and therapy of ID has been made over the last decade.What is New:• Our expert panel provides ID management recommendations based on the best available evidence.• They include strategies for ID diagnosis and therapy, both oral and intravenous.

Usefulness of multiple electrode aggregometry as a screening tool for bleeding disorders in a pediatric hospital.

Platelet function testing is a cornerstone in the diagnostic investigation of patients with a bleeding history. Multiple electrode aggregometry (MEA) has been shown to detect von Willebrand disease (VWD), platelet function disorders, and drug-induced bleeding disorders. However, there are few studies supporting its successful use in children. We have implemented and used MEA over 3 years in our hemostasis laboratory in order to study its usefulness to supplement and expedite diagnosis. This is a retrospective, single-center, cohort study of 109 hospitalized children who underwent a laboratory investigation of hemostasis and either had a reported bleeding history or an abnormal bleeding episode. Plasmatic coagulation testing, blood counts, plasmatic von Willebrand testing, platelet function analyzer (PFA-100), and impedance aggregometry (MEA) were performed in all children. Light transmission aggregometry testing was performed as needed. In 41 cases (37.6%), a working diagnosis was made; a primary hemostatic disorder was detected in 35 children (VWD (n = 16), platelet disorder (n = 15), and valproic acid therapy-induced bleeding disorder (n = 3), acetylsalicylic acid-related bleeding (n = 1). In patients diagnosed with VWD, MEA ristocetin-induced platelet aggregation test (RISTO) high test revealed abnormally low aggregation in six patients (43.8%); whereas in patients diagnosed with a platelet function disorder, abnormally low values were found by MEA in only three children (20%). Three of the four children with laboratory evidence of drug-induced platelet dysfunction had abnormalities on MEA. There were no cases in which an abnormal MEA result was used to make a previously undetermined diagnosis. Retrospectively, MEA has demonstrated limited additional diagnostic value beyond standard laboratory testing for detecting defects of primary hemostasis in children.

Newborn screening for sickle cell disease in Europe: recommendations from a Pan-European Consensus Conference.

Sickle Cell Disease (SCD) is an increasing global health problem and presents significant challenges to European health care systems. Newborn screening (NBS) for SCD enables early initiation of preventive measures and has contributed to a reduction in childhood mortality from SCD. Policies and methodologies for NBS vary in different countries, and this might have consequences for the quality of care and clinical outcomes for SCD across Europe. A two-day Pan-European consensus conference was held in Berlin in April 2017 in order to appraise the current status of NBS for SCD and to develop consensus-based statements on indications and methodology for NBS for SCD in Europe. More than 50 SCD experts from 13 European countries participated in the conference. This paper aims to summarise the discussions and present consensus recommendations which can be used to support the development of NBS programmes in European countries where they do not yet exist, and to review existing programmes.

RAS-pathway mutation patterns define epigenetic subclasses in juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative disorder of early childhood characterized by mutations activating RAS signaling. Established clinical and genetic markers fail to fully recapitulate the clinical and biological heterogeneity of this disease. Here we report DNA methylome analysis and mutation profiling of 167 JMML samples. We identify three JMML subgroups with unique molecular and clinical characteristics. The high methylation group (HM) is characterized by somatic PTPN11 mutations and poor clinical outcome. The low methylation group is enriched for somatic NRAS and CBL mutations, as well as for Noonan patients, and has a good prognosis. The intermediate methylation group (IM) shows enrichment for monosomy 7 and somatic KRAS mutations. Hypermethylation is associated with repressed chromatin, genes regulated by RAS signaling, frequent co-occurrence of RAS pathway mutations and upregulation of DNMT1 and DNMT3B, suggesting a link between activation of the DNA methylation machinery and mutational patterns in JMML.

Impact of genetic variants on haematopoiesis in patients with thrombocytopenia absent radii (TAR) syndrome.

Thrombocytopenia absent radii (TAR) syndrome is clearly defined by the combination of radial aplasia and reduced platelet counts. The genetics of TAR syndrome has recently been resolved and comprises a microdeletion on Chromosome 1 including the RBM8A gene and a single nucleotide polymorphism (SNP) either at the 5' untranslated region (5'UTR) or within the first intron of RBM8A. Although phenotypically readily diagnosed after birth, the genetic determination of particular SNPs in TAR syndrome harbours valuable information to evaluate disease severity and treatment decisions. Here, we present clinical data in a cohort of 38 patients and observed that platelet counts in individuals with 5'UTR SNP are significantly lower compared to patients bearing the SNP in intron 1. Moreover, elevated haemoglobin values could only be assessed in patients with 5'UTR SNP whereas white blood cell count is unaffected, indicating that frequently observed anaemia in TAR patients could also be SNP-dependent whereas leucocytosis does not correlate with genetic background. However, this report on a large cohort provides an overview of important haematological characteristics in TAR patients, facilitating evaluation of the various traits in this disease and indicating the importance of genetic validation for TAR syndrome.