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Objective: To investigate the clinical features, treatment regime, and outcome of pediatric acute myeloid leukemia (AML) with DEK-NUP214 fusion gene. Methods: The clinical data, genetic and molecular results, treatment process and survival status of 7 cases of DEK-NUP214 fusion gene positive AML children admitted to the Pediatric Blood Diseases Center of Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences from May 2015 to February 2022 were analyzed retrospectively. Results: DEK-NUP214 fusion gene positive AML accounted for 1.02% (7/683) of pediatric AML diagnosed in the same period, with 4 males and 3 females. The age of disease onset was 8.2 (7.5, 9.5) years. The blast percentage in bone marrow was 0.275 (0.225, 0.480), and 6 cases were M5 by FAB classification. Pathological hematopoiesis was observed in all cases except for one whose bone marrow morphology was unknown. Three cases carried FLT3-ITD mutations, 4 cases carried NRAS mutations, and 2 cases carried KRAS mutations. After diagnosis, 4 cases received IAE induction regimen (idarubicin, cytarabine and etoposide), 1 case received MAE induction regimen (mitoxantrone, cytarabine and etoposide), 1 case received DAH induction regimen (daunorubicin, cytarabine and homoharringtonine) and 1 case received DAE induction regimen (daunorubicin, cytarabine and etoposide). Complete remission was achieved in 3 cases after one course of induction. Four cases who did not achieved complete remission received CAG (aclarubicin, cytarabine and granulocyte colony-stimulating factor), IAH (idarubicin, cytarabine and homoharringtonine), CAG combined with cladribine, and HAG (homoharringtonine, cytarabine and granulocyte colony-stimulating factor) combined with cladribine reinduction therapy, respectively, all 4 cases reached complete remission. Six patients received hematopoietic stem cell transplantation (HSCT) after 1-2 sessions of intensive consolidation treatment, except that one case was lost to follow-up after complete remission. The time from diagnosis to HSCT was 143 (121, 174) days. Before HSCT, one case was positive for flow cytometry minimal residual disease and 3 cases were positive for DEK-NUP214 fusion gene. Three cases accepted haploid donors, 2 cases accepted unrelated cord blood donors, and 1 case accepted matched sibling donor. The follow-up time was 20.4 (12.9, 53.1) months, the overall survival and event free survival rates were all 100%. Conclusions: Pediatric AML with DEK-NUP214 fusion gene is a unique and rare subtype, often diagnosed in relatively older children. The disease is characterized with a low blast percentage in bone marrow, significant pathological hematopoiesis and a high mutation rate in FLT3-ITD and RAS genes. Low remission rate by chemotherapy only and very high recurrence rate indicate its high malignancy and poor prognosis. Early HSCT after the first complete remission can improve its prognosis.

Objective: To explore the clinical features of bloodstream infections (BSI) in children with acute myeloid leukemia (AML) during the first induction chemotherapy. Methods: The clinical data, pathogen of BSI, antibiotic susceptibility in vitro, complications and prognosis of 204 newly diagnosed AML children admitted to Blood Diseases Hospital, Chinese Academy of Medical Sciences from August 2009 to December 2015 were analyzed retrospectively. χ 2 test was used for the comparison between groups and Logistic regression was used for BSI risk factor analysis. Results: Among 204 patients, 116 were males and 88 were females. The age was 8 (ranged from 1 to 14) years. Among them, 170 patients received MAE chemotherapies (etoposide, mitoxantrone and cytarabine) and 25 received IAE chemotherapies (etoposide, idarubicin and cytarabine). The other 9 patients used granulocyte colony stimulating factor (G-CSF)-priming regimen (aclacinomycin or homoharringtonine, cytarabine and G-CSF) for induction treatments. A total of 28 patients experienced BSI and the incidence rate was 13.7% (28/204), 26 of them developed BSI once and 2 patients developed twice. Gram-positive bacteria were predominant pathogens accounting for 53.3% (16/30) while gram-negative bacteria accounting for 40.0% (12/30) and fungal accounted for 6.7% (2/30). The most common detected pathogens were Coagulase negative Staphylococcus (CoNS, 26.7% (8/30)), followed by Streptococcus spp. (13.3% (4/30)) and Escherichia coli (13.3% (4/30)). Among Gram-negative bacteria (GNB), 3 cases showed carbapenem resistance and 2 cases were Stenotrophomonas maltophilia. BSI-related mortality was 28.6% (8/28). Infections caused by drug-resistant GNB or fungi resulted in 6 fatal cases. The incidence rate of BSI in group with severe neutropenia was higher than in group without it (16.6% (25/151) vs . 5.7% (3/53), χ²=3.933, P =0.047). Multivariable analysis showed severe neutropenia at the onset of fever was independent risk factor of BSI ( OR =4.258,95% CI 1.097-16.524, P =0.036). Conclusions: During the first induction chemotherapy courses, Gram-positive bacteria cause most of the BSI. Drug-resistant bacteria related infection often result in fatal outcomes. Severe neutropenia is a significant risk factor.

Objective: To analyze the clinical features, bone marrow features, and gene mutations of children with familial platelet disorder with predisposition to myeloid leukemia (FPD/AML) caused by a RUNX1 germline mutation as well as their family members. Methods: The clinical data and gene mutations of a child with FPD/AML hospitalized in the Pediatric Blood Disease Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, and some family members were extracted and analyzed. The literature was searched using "RUNX1 germline mutation" and "FPD/AML" as keywords in the Chinese databases; also PubMed was reviewed until September 2020. Results: A male patient aged 5 with dermatorrhagia was admitted due to thrombocytopenia for more than 3 years. The laboratory tests revealed a peripheral blood routine (WBC 6.38×10(9)/L, HGB 113 g/L, PLT 54×10(9)/L, NEUT 4.03×10(9)/L, and MPV 9.1 fl) . Bone marrow smear revealed dysplasia of megakaryocytes. The immunohistochemistry for CD42b and CD41 highlighted small mononuclear megakaryocytes. Second generation sequencing revealed RUNX1 (exon3:c.520delC: p.R174Efs*10, NM_001001890) frameshift mutations, and its germline mutation was verified via genetic detection of oral epithelial cells. Five members of the family had blood diseases and successively died. The child's mother and maternal grandfather were sequenced for the second generation, and RUNX1 frameshift mutation was detected in the same locus as the child. However, the clinical features among them were different. A total of 37 English literatures were retrieved, and more than 70 FPD/AML families were reported. No relevant Chinese literature was retrieved. Conclusion: Runx1 germline mutations cause FPD/AML with a high risk of progression to myeloid malignancy. Family members carrying the same mutations may exhibit different clinical features and severity.