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Introduction Thanks to next-generation sequencing (NGS) approaches, the list of genetic syndromes that cause thrombocytopenia has grown in recent years and now includes over 40 genes (1). However, there are [...], 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.

Background: Data on dermatological manifestations of Costello syndrome (CS) remain heterogeneous and lack in validated description. Objectives: To describe the dermatological manifestations of CS; compare them with the literature findings; assess those discriminating CS from other RASopathies, including cardiofaciocutaneous syndrome (CFCS) and the main types of Noonan syndrome (NS); and test for dermatological phenotype–genotype correlations. Methods: We performed a 10‐year, large, prospective, multicentric, collaborative dermatological and genetic study. Results: Thirty‐one patients were enrolled. Hair abnormalities were ubiquitous, including wavy or curly hair and excessive eyebrows, respectively in 68% and 56%. Acral excessive skin (AES), papillomas and keratotic papules (PKP), acanthosis nigricans (AN), palmoplantar hyperkeratosis (PPHK) and 'cobblestone' papillomatous papules of the upper lip (CPPUL), were noted respectively in 84%, 61%, 65%, 55% and 32%. Excessive eyebrows, PKP, AN, CCPUL and AES best differentiated CS from CFCS and NS. Multiple melanocytic naevi (>50) may constitute a new marker of attenuated CS associated with intragenic duplication in HRAS. Oral acitretin may be highly beneficial for therapeutic management of PPHK. No significant dermatological phenotype–genotype correlation was determined between patients with and without HRAS c.34G>A (p.G12S). Conclusions and Relevance: This validated phenotypic characterization of a large number of patients with CS will allow future researchers to make a positive diagnosis, and to differentiate CS from CFCS and NS. [ABSTRACT FROM AUTHOR]

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Summary: The nucleoside analogue, 2‐chlorodeoxyadenosine (2CDA), was reported to be an active treatment for childhood Langerhans cell histiocytosis (LCH) without risk organ (RO−) involvement. However, we lack data on long‐term effects of 2CDA treatment, including the disease reactivation rate, permanent sequelae and long‐term tolerance. This study included 44 children from the French LCH registry, treated for a RO− LCH with 2CDA monotherapy (median number of six courses). The median age at the beginning of 2CDA was 3·6 years (range, 0·3–19·7 years) and the median follow‐up after was 5·4 years (range, 0·6–15·1 years). Objective response to 2CDA was observed in 25 patients (56·8%), while six patients (13·6%) had stable disease and 13 patients (29·5%) exhibited progressive disease. Among patients without progression, only two experienced disease reactivation after 2CDA discontinuation. The five‐year cumulative incidence of disease progression or reactivation after 2CDA therapy initiation was 34·3%. The lymphopenia reported in all cases [72% below absolute lymphocyte count (ALC) of 0·5 G/l], was addressed with appropriate prophylactic measures. Other toxicities above grade 2 were uncommon, and no second malignant neoplasm or neuropathy was reported. The five‐year overall survival was 97·7%. In conclusion, we could confirm that 2CDA monotherapy was a beneficial long‐term therapy for treating patients with RO− LCH. Appropriate management of induced immune deficiency is mandatory. [ABSTRACT FROM AUTHOR]

Activated phosphoinositide-3-kinase δ syndrome (APDS) is an inborn error of immunity (IEI) with infection susceptibility and immune dysregulation, clinically overlapping with other conditions. Management depends on disease evolution, but predictors of severe disease are lacking. This study sought to report the extended spectrum of disease manifestations in APDS1 versus APDS2; compare these to CTLA4 deficiency, NFKB1 deficiency, and STAT3 gain-of-function (GOF) disease; and identify predictors of severity in APDS. Data was collected from the ESID (European Society for Immunodeficiencies)-APDS registry and was compared with published cohorts of the other IEIs. The analysis of 170 patients with APDS outlines high penetrance and early onset of APDS compared to the other IEIs. The large clinical heterogeneity even in individuals with the same PIK3CD variant E1021K illustrates how poorly the genotype predicts the disease phenotype and course. The high clinical overlap between APDS and the other investigated IEIs suggests relevant pathophysiological convergence of the affected pathways. Preferentially affected organ systems indicate specific pathophysiology: bronchiectasis is typical of APDS1; interstitial lung disease and enteropathy are more common in STAT3 GOF and CTLA4 deficiency. Endocrinopathies are most frequent in STAT3 GOF, but growth impairment is also common, particularly in APDS2. Early clinical presentation is a risk factor for severe disease in APDS. APDS illustrates how a single genetic variant can result in a diverse autoimmune-lymphoproliferative phenotype. Overlap with other IEIs is substantial. Some specific features distinguish APDS1 from APDS2. Early onset is a risk factor for severe disease course calling for specific treatment studies in younger patients. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this work is to assess the clinical outcome of pediatric patients diagnosed with pheochromocytoma and paraganglioma (PPGL) detected in France since 2000. Methods A retrospective multicenter study was conducted that included all patients younger than 18 years with PPGL diagnosed in France between 2000 and 2016. Patients were identified from 4 different sources: the National Registry of Childhood Solid Tumors, the French Pediatric Rare Tumors Database, the French registry of succinate dehydrogenase (SDH)-related hereditary paraganglioma, and the nationwide TenGen network. Results Among 113 eligible patients, 81 children with available data were enrolled (41 with adrenal and 40 with extra-adrenal PPGL). At diagnosis, 11 had synchronous metastases. After a median follow-up of 53 months, 27 patients experienced a new event (n = 7 second PPGL, n = 1 second paraganglioma [PGL], n = 8 local recurrences, n = 10 metastatic relapses, n = 1 new tumor) and 2 patients died of their disease. The 3- and 10-year event-free survival rates were 80% (71%-90%) and 39% (20%-57%),respectively, whereas the overall survival rate was 97% (93%-100%)at 3 and 10 years. A germline mutation in one PPGL-susceptibility gene was identified in 53 of the 68 (77%) patients who underwent genetic testing (SDHB [n = 25], VHL [n = 21], RET [n = 2], HIF2A [n = 2], SDHC [n = 1], SDHD [n = 1], NF1 [n = 1]). Incomplete resection and synchronous metastases were associated with higher risk of events (P  = .011, P  = .004), but presence of a germline mutation was not (P  = .11). Conclusions Most pediatric PPGLs are associated with germline mutations and require specific follow-up because of the high risk of tumor recurrence. [ABSTRACT FROM AUTHOR]

Background: Medulloblastoma (MB) is one of the most prevalent embryonal malignant brain tumors. Current classification organizes these tumors into four molecular subgroups (WNT, SHH, Group 3, and Group 4 MB). Recently, a comprehensive classification has been established, identifying numerous subtypes, some of which exhibit a poor prognosis. It is critical to establish effective subtyping methods for accurate diagnosis and patient's management that strikes a delicate balance between improving outcomes and minimizing the risk of comorbidities., Methods: We evaluated the ability of Nanopore sequencing to provide clinically relevant methylation and copy number profiles of MB. Nanopore sequencing was applied to an EPIC cohort of 44 frozen MB, benchmarked against the gold standard EPIC array, and further evaluated on an integrated diagnosis cohort of 116 MB., Results: Most MB of both cohorts (42/44; 95.5% and 106/116; 91.4% respectively) were accurately subgrouped by Nanopore sequencing. Employing Flongle flow cells for 18 MB allowed a more rapid and cost-effective analysis, with 94.4% (17/18) being correctly classified. Nanopore sequencing enabled us to accurately subtype 28/30 (93.3%) MB., Conclusion: This study, conducted on the largest cohort of MB analyzed with Nanopore sequencing to date, establishes the proof of concept that this modern and innovative technology is well-suited for MB classification. Nanopore sequencing demonstrates a robust capacity for precise subtyping of MB, a critical advancement that holds significant potential for enhancing patient stratification in future clinical trials. Its ability to deliver quick and cost-effective results firmly establishes it as a game-changer in the field of MB classification., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Neuro-Oncology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

The announcement of a cancer diagnosis is a crucial moment in the management of the disease, as it is the starting point for a relationship of trust between patient and caregiver. In 2005, this issue led to the creation of an announcement system as part of the 2003-2007 cancer plan, but its implementation in practice remains uncertain. Pediatric oncology has its own specificities, with a triangular relationship and the need for doctors to adapt to the child's age. These skills require special training, and training opportunities vary from one area to another. To this end, the Angers and Caen centers have developed simulation exercises for training in pediatric oncology announcement. These consist of a theoretical part, followed by an announcement interview with actors, then a debriefing. Evaluation questionnaires are completed by learners before and after the session, and have highlighted the usefulness of this training, particularly in helping them to feel better prepared to face this stressful moment. As simulation has proved its educational value in the healthcare field, GOCE has developed simulation-based training courses for interns/CCAs/assistants in the territory. These courses are much appreciated and are proving extremely useful in clinical practice. This has led the SFCE to extend these courses to all CCAs and young PHs in pediatric oncology in France., (Copyright © 2024. Published by Elsevier Masson SAS.)

Background: ELP1 pathogenic variants (PV) have been recently identified as the most frequent variants predisposing to Sonic Hedgehog (SHH) medulloblastomas (MB); however, guidelines are still lacking for genetic counseling in this new syndrome., Methods: We retrospectively reviewed clinical and genetic data of a French series of 29 ELP1 -mutated MB., Results: All patients developed SHH-MB, with a biallelic inactivation of PTCH1 found in 24 tumors. Other recurrent alterations encompassed the TP53 pathway and activation of MYCN/MYCL signaling. The median age at diagnosis was 7.3 years (range: 3-14). ELP1 -mutated MB behave as sporadic cases, with similar distribution within clinical and molecular risk groups and similar outcomes (5 y - OS = 86%); no unusual side effect of treatments was noticed. Remarkably, a germline ELP1 PV was identified in all patients with available constitutional DNA ( n  = 26); moreover, all tested familial trio ( n  = 11) revealed that the PVs were inherited. Two of the 26 index cases from the French series had a family history of MB; pedigrees from these patients and from 1 additional Dutch family suggested a weak penetrance. Apart from MB, no cancer was associated with ELP1 PVs; second tumors reported in 4 patients occurred within the irradiation fields, in the usual time-lapse for expected radiotherapy-induced neoplasms., Conclusions: The low penetrance, the "at risk' age window limited to childhood and the narrow tumor spectrum, question the actual benefit of genetic screening in these patients and their family. Our results suggest restricting ELP1 germline sequencing to patients with SHH-MB, depending on the parents" request., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press, the Society for Neuro-Oncology and the European Association of Neuro-Oncology.)

Importance: Innovative anticancer therapies for children, adolescents, and young adults are regularly prescribed outside their marketing authorization or through compassionate use programs. However, no clinical data of these prescriptions is systematically collected., Objectives: To measure the feasibility of the collection of clinical safety and efficacy data of compassionate and off-label innovative anticancer therapies, with adequate pharmacovigilance declaration to inform further use and development of these medicines., Design, Setting, and Participants: This cohort study included patients treated at French pediatric oncology centers from March 2020 to June 2022. Eligible patients were aged 25 years or younger with pediatric malignant neoplasms (solid tumors, brain tumors, or hematological malignant neoplasms) or related conditions who received compassionate use or off-label innovative anticancer therapies. Follow up was conducted through August 10, 2022., Exposures: All patients treated in a French Society of Pediatric Oncology (SFCE) center., Main Outcomes and Measures: Collection of adverse drug reactions and anticancer activity attributable to the treatment., Results: A total of 366 patients were included, with a median age of 11.1 years (range, 0.2-24.6 years); 203 of 351 patients (58%) in the final analysis were male. Fifty-five different drugs were prescribed, half of patients (179 of 351 [51%]) were prescribed these drugs within a compassionate use program, mainly as single agents (74%) and based on a molecular alteration (65%). Main therapies were MEK/BRAF inhibitors followed by multi-targeted tyrosine kinase inhibitors. In 34% of patients at least a grade 2 clinical and/or grade 3 laboratory adverse drug reaction was reported, leading to delayed therapy and permanent discontinuation of the innovative therapy in 13% and 5% of patients, respectively. Objective responses were reported in 57 of 230 patients (25%) with solid tumors, brain tumors, and lymphomas. Early identification of exceptional responses supported the development of specific clinical trials for this population., Conclusions and Relevance: This cohort study of the SACHA-France (Secured Access to Innovative Medicines for Children with Cancer) suggested the feasibility of prospective multicenter clinical safety and activity data collection for compassionate and off-label new anticancer medicines. This study allowed adequate pharmacovigilance reporting and early identification of exceptional responses allowing further pediatric drug development within clinical trials; based on this experience, this study will be enlarged to the international level.

The spectrum of somatic mutations in pediatric histiocytoses and their clinical implications are not fully characterized, especially for non-Langerhans cell histiocytosis (-LCH) subtypes. A cohort of 415 children with histiocytosis from the French histiocytosis registry was reviewed and analyzed for BRAF V600E . Most BRAF WT samples were analyzed by next-generation sequencing (NGS) with a custom panel of genes for histiocytosis and myeloid neoplasia. Of 415 case samples, there were 366 LCH, 1 Erdheim-Chester disease, 21 Rosai-Dorfman disease (RDD), 21 juvenile xanthogranuloma (JXG, mostly with severe presentation), and 6 malignant histiocytosis (MH). BRAF V600E was the most common mutation found in LCH (50.3%, n = 184). Among 105 non-BRAF V600E -mutated LCH case samples, NGS revealed mutations as follows: MAP2K1 (n = 44), BRAF exon 12 deletions (n = 26), and duplications (n = 8), other BRAF V600 codon mutation (n = 4), and non-MAP-kinase pathway genes (n = 5). Wild-type sequences were identified in 17.1% of samples. BRAF V600E was the only variant significantly correlated with critical presentations: organ-risk involvement and neurodegeneration. MAP-kinase pathway mutations were identified in seven RDD (mostly MAP2K1) and three JXG samples, but most samples were wild-type on NGS. Finally, two MH samples had KRAS mutations, and one had a novel BRAF G469R mutation. Rarely, we identified mutations unrelated to MAP-kinase pathway genes. In conclusion, we characterized the mutational spectrum of childhood LCH and clinical correlations of variants and subtypes. Variants responsible for JXG and RDD were not elucidated in more than half of the cases, calling for other sequencing approaches., (© 2023 The Authors. American Journal of Hematology published by Wiley Periodicals LLC.)

The outcomes of adolescents/young adults with osteosarcoma have not improved in decades. The chaotic karyotype of this rare tumor has precluded the identification of prognostic biomarkers and patient stratification. We reasoned that transcriptomic studies should overcome this genetic complexity. RNA sequencing (RNA-seq) of 79 osteosarcoma diagnostic biopsies identified stable independent components that recapitulate the tumor and microenvironment cell composition. Unsupervised classification of the independent components stratified this cohort into favorable (G1) and unfavorable (G2) prognostic tumors in terms of overall survival. Multivariate survival analysis ranked this stratification as the most influential variable. Functional characterization associated G1 tumors with innate immunity and G2 tumors with angiogenic, osteoclastic, and adipogenic activities as well as PPARγ pathway upregulation. A focused gene signature that predicted G1/G2 tumors from RNA-seq data was developed and validated within an independent cohort of 82 osteosarcomas. This signature was further validated with a custom NanoString panel in 96 additional osteosarcomas. This study thus proposes new biomarkers to detect high-risk patients and new therapeutic options for osteosarcoma., Significance: These findings indicate that the osteosarcoma microenvironment composition is a major feature to identify hard-to-treat patient tumors at diagnosis and define the biological pathways and potential actionable targets associated with these tumors., (©2022 American Association for Cancer Research.)

Purpose: The purpose of this work is to assess the clinical outcome of pediatric patients diagnosed with pheochromocytoma and paraganglioma (PPGL) detected in France since 2000., Methods: A retrospective multicenter study was conducted that included all patients younger than 18 years with PPGL diagnosed in France between 2000 and 2016. Patients were identified from 4 different sources: the National Registry of Childhood Solid Tumors, the French Pediatric Rare Tumors Database, the French registry of succinate dehydrogenase (SDH)-related hereditary paraganglioma, and the nationwide TenGen network., Results: Among 113 eligible patients, 81 children with available data were enrolled (41 with adrenal and 40 with extra-adrenal PPGL). At diagnosis, 11 had synchronous metastases. After a median follow-up of 53 months, 27 patients experienced a new event (n = 7 second PPGL, n = 1 second paraganglioma [PGL], n = 8 local recurrences, n = 10 metastatic relapses, n = 1 new tumor) and 2 patients died of their disease. The 3- and 10-year event-free survival rates were 80% (71%-90%) and 39% (20%-57%),respectively, whereas the overall survival rate was 97% (93%-100%)at 3 and 10 years. A germline mutation in one PPGL-susceptibility gene was identified in 53 of the 68 (77%) patients who underwent genetic testing ( SDHB [n = 25], VHL [n = 21], RET [n = 2], HIF2A [n = 2], SDHC [n = 1], SDHD [n = 1], NF1 [n = 1]). Incomplete resection and synchronous metastases were associated with higher risk of events ( P  = .011, P  = .004), but presence of a germline mutation was not ( P  = .11)., Conclusions: Most pediatric PPGLs are associated with germline mutations and require specific follow-up because of the high risk of tumor recurrence., (© Endocrine Society 2020.)

Purpose: Patients with primary immunodeficiency (PID) are at risk of serious complications. However, data on the incidence and causes of emergency hospital admissions are scarce. The primary objective of the present study was to describe emergency hospital admissions among patients with PID, with a view to identifying "at-risk" patient profiles., Methods: We performed a prospective observational 12-month multicenter study in France via the CEREDIH network of regional PID reference centers from November 2010 to October 2011. All patients with PIDs requiring emergency hospital admission were included., Results: A total of 200 admissions concerned 137 patients (73 adults and 64 children, 53% of whom had antibody deficiencies). Thirty admissions were reported for 16 hematopoietic stem cell transplantation recipients. When considering the 170 admissions of non-transplant patients, 149 (85%) were related to acute infections (respiratory tract infections and gastrointestinal tract infections in 72 (36%) and 34 (17%) of cases, respectively). Seventy-seven percent of the admissions occurred during winter or spring (December to May). The in-hospital mortality rate was 8.8% (12 patients); death was related to a severe infection in 11 cases (8%) and Epstein-Barr virus-induced lymphoma in 1 case. Patients with a central venous catheter (n = 19, 13.9%) were significantly more hospitalized for an infection (94.7%) than for a non-infectious reason (5.3%) (p = 0.04)., Conclusion: Our data showed that the annual incidence of emergency hospital admission among patients with PID is 3.4%. The leading cause of emergency hospital admission was an acute infection, and having a central venous catheter was associated with a significantly greater risk of admission for an infectious episode.

About one third of patients with rhabdoid tumors (RT) harbor a heterozygous germline variant in SMARCB1. Molecular diagnosis therefore keeps a crucial place in the diagnosis of RT, and genetic counseling should be systematically recommended. However, immunohistochemistry has progressively replaced molecular tools to assess the status of SMARCB1 in tumors; the necessity of analyzing SMARCB1 status in the tumor may thus be less considered by neuropathologists and pediatric neuro-oncologists. In the present manuscript as aforementioned, we report on two patients with bifocal RT in the first month of life and in whom no germline variant was initially found in the SMARCB1 coding sequence. Careful analysis of SMARCB1 status in the tumors revealed that only one of the two inactivating hits was found in the coding sequence. By sequencing the tumor cells RNA, we were able to detect an insertion with an abnormal sequence, due to the same intronic variant of SMARCB1, which led to the exonisation of the first intron. This cryptic variant was absent in the germline DNA of both patients. Of note, we previously reported one patient with the same deep intronic variant in the germline in a soft tissue RT. To our mind, this additional report on two patients clearly demonstrates that this intronic variant is a new hotspot that should now be systematically added to the germline screening of SMARCB1. We therefore recommend searching for and cautiously interpreting germline analysis if SMARCB1 has not been extensively studied in the tumor.

Evans syndrome (ES) is a rare autoimmune disorder whose long-term outcome is not well known. In France, a collaborative pediatric network set up via the National Rare Disease Plan now provides comprehensive clinical data in children with this disease. Patients aged less than 18 years at the initial presentation of autoimmune cytopenia have been prospectively included into a national observational cohort since 2004. The definition of ES was restricted to the simultaneous or sequential association of autoimmune hemolytic anemia (AIHA) and immune thrombocytopenic purpura (ITP). Cases were deemed secondary if associated with a primitive immunodeficiency or systemic lupus erythematosus. In December 2014, we analyzed the data pertaining to 156 children from 26 centers with ES whose diagnosis was made between 1981 and 2014. Median age (range) at the onset of cytopenia was 5.4 years (0.2-17.2). In 85 sequential cases, the time lapse between the first episodes of AIHA and ITP was 2.4 years (0.1-16.3). The follow-up period as from ES diagnosis was 6.5 years (0.1-28.8). ES was secondary, revealing another underlying disease, in 10% of cases; various associated immune manifestations (mainly lymphoproliferation, other autoimmune diseases, and hypogammaglobulinemia) were observed in 60% of cases; and ES remained primary in 30% of cases. Five-year ITP and AIHA relapse-free survival were 25 and 61%, respectively. Overall, 69% of children required one or more second-line immune treatments, and 15 patients (10%) died at the age of 14.3 years (1.7-28.1). To our knowledge, this is the first consistent long-term clinical description of this rare syndrome. It underscores the high rate of associated immune manifestations and the burden of long-term complications and treatment toxicity. Future challenges include (1) the identification of the underlying genetic defects inducing immune dysregulation and (2) the need to better characterize patient subgroups and second-line treatment strategies.