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Children with Down syndrome are at a high risk of developing transient abnormal myelopoiesis (TAM; synonym: TMD) or myeloid leukemia (ML-DS). While most patients with TAM are asymptomatic and go into spontaneous remission without a need for therapy, around 20% of patients die within the first six months due to TAM-related complications. Another 20-30% of patients progress from TAM to ML-DS. ML-DS patients are particularly vulnerable to therapy-associated toxicity, but the prognosis of relapsed ML-DS is extremely poor - thus, ML-DS therapy schemata must strive for a balance between appropriate efficacy (to avoid relapses) and treatment-related toxicity. This guideline presents diagnostic and therapeutic strategies for TAM and ML-DS based on the experience and results of previous clinical studies from the BFM working group, which have helped reduce the risk of early death in symptomatic TAM patients using low-dose cytarabine, and which have achieved excellent cure rates for ML-DS using intensity-reduced treatment protocols., Competing Interests: D. Reinhardt has advisory roles for Celgene Corporation, Novartis, Bluebird Bio, Janssen, and receives research funding from CLS Behring and Roche. J.-H. Klusmann has advisory roles for Bluebird Bio, Novartis, Roche and Jazz Pharmaceuticals., (Thieme. All rights reserved.)

During development, gene expression is tightly controlled to facilitate the generation of the diverse cell types that form the central nervous system. Brahma-related gene 1 (Brg1, also known as Smarca4) is the catalytic subunit of the SWItch/sucrose nonfermentable (SWI/SNF) chromatin remodeling complex that regulates transcription. We investigated the role of Brg1 between embryonic day 6.5 (E6.5) and E14.5 in Sox2-positive neural stem cells (NSCs). Being without major consequences at E6.5 and E14.5, loss of Brg1 between E7.5 and E12.5 resulted in the formation of rosette-like structures in the subventricular zone, as well as morphological alterations and enlargement of neural retina (NR). Additionally, Brg1-deficient cells showed decreased survival in vitro and in vivo. Furthermore, we uncovered distinct changes in gene expression upon Brg1 loss, pointing towards impaired neuron functions, especially those involving synaptic communication and altered composition of the extracellular matrix. Comparison with mice deficient for integrase interactor 1 (Ini1, also known as Smarcb1) revealed that the enlarged NR was Brg1 specific and was not caused by a general dysfunction of the SWI/SNF complex. These results suggest a crucial role for Brg1 in NSCs during brain and eye development., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2021. Published by The Company of Biologists Ltd.)

HOX genes are highly conserved, and their precisely controlled expression is crucial for normal hematopoiesis. Accordingly, deregulation of HOX genes can cause leukemia. However, despite of intensive research on the coding HOX genes, the role of the numerous long noncoding RNAs (lncRNAs) within the HOX clusters during hematopoiesis and their contribution to leukemogenesis are incompletely understood. Here, we show that the lncRNA HOXA10-AS, located antisense to HOXA10 and mir-196b in the HOXA cluster, is highly expressed in hematopoietic stem cells (HSCs) as well as in KMT2A-rearranged and NPM1 mutated acute myeloid leukemias (AMLs). Using short hairpin RNA- and locked nucleic acid-conjugated chimeric antisense oligonucleotide (LNA-GapmeR)-mediated HOXA10-AS-knockdown and CRISPR/Cas9-mediated excision in vitro, we demonstrate that HOXA10-AS acts as an oncogene in KMT2A-rearranged AML. Moreover, HOXA10-AS knockdown severely impairs the leukemic growth of KMT2A-rearranged patient-derived xenografts in vivo, while high HOXA10-AS expression can serve as a marker of poor prognosis in AML patients. Lentiviral expression of HOXA10-AS blocks normal monocytic differentiation of human CD34+ hematopoietic stem and progenitor cells. Mechanistically, we show that HOXA10-AS localizes in the cytoplasm and acts in trans to induce NF-κB target genes. In total, our data imply that the normally HSC-specific HOXA10-AS is an oncogenic lncRNA in KMT2A-r AML. Thus, it may also represent a potential therapeutic target in KMT2A-rearranged AML., (© 2019 by The American Society of Hematology.)