The rapid spread of the coronavirus disease 2019 (COVID-19) pandemic has rapidly led to the establishment of social distancing measures on a global scale to try to protect the general population as well as patients. 1 An unprecedented wave of dedicated preclinical and clinical research projects has also been launched.

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During the first successive waves of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants, adult patients with sickle cell disease (SCD), particularly older patients and those with the SC genotype, were reported to be at risk of severe coronavirus disease 2019 (COVID-19), whereas children seemed relatively spared. 1 Although the B.1.1.529 (Omicron) variant was considered to induce less severe forms than the Delta variant in adults, the last Omicron wave resulted in a surprising increase in hospitalised paediatric cases. 2 Nevertheless, little is known about the severity of the Omicron variant in patients with SCD, especially in children. In France, the COVID-19 vaccine has been recommended for adolescents with SCD aged >12 years since 28 May 2021, and for children with SCD aged 5-11 years since 30 November 2021. The objective of this study was to focus on severe outcomes in children with SCD infected by SARS-CoV-2 during the Omicron wave within the landscape of widespread COVID-19 vaccination.All paediatricians and adult-patient practitioners involved in SCD management in France were contacted by our national SCD consortia (see Ref. [1] for details) to report patients with SCD hospitalised with severe COVID-19 infection from 27 December 2021 to 30 April 2022, corresponding to the Omicron wave in France. SARS-CoV-2 infection was confirmed by reverse transcription polymerase chain reaction or rapid antigen-detection tests.Severe COVID-19 was defined as hospitalised patients with SCD with at least one of the following criteria: oxygen therapy >3 L/min, intensive care unit (ICU) admission, pulmonary embolism (PE), deep vein thrombosis (DVT), stroke, multisystem inflammatory syndrome in children (MIS-C), or a haemoglobin (Hb) level of <50 g/L.Anonymised data were collected by the investigators using standardised forms with a minimal dataset (Table 1). The only recorded biological value was the Hb level at admission. In line with the French legislation on retrospective studies of routine clinical practice, participants were not required to give their written informed consent. Patients or their parent/guardian were informed that their medical data could be used for research purposes, in accordance with General Data Protection Regulation 2016/679.During the 4-month Omicron wave, 29 patients with SCD with severe COVID-19 were reported by 13 French centres. In all, 17 (59%) were children (aged < 18 years), which is

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 Jean-François Emile and Sébastien Heritier contributed equally to this study.

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