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Changes of nuclear localization of lineage‐specific genes from a transcriptionally inert to permissive environment are a crucial step in establishing the identity of a cell. Noncoding RNA transcription‐mediated genome folding and activation of target gene expression have been found in a variety of cell types. Noncoding RNA ThymoD (thymocyte differentiation factor) transcription at superenhancers is essential for mouse T‐cell lineage commitment. The cessation of ThymoD transcription abolishes transcription‐mediated demethylation, recruiting looping factors such as the cohesin complex, CCCTC‐binding factor (CTCF), ultimately leading to the phenotype of severe combined immunodeficiency and T‐cell leukemia/lymphoma. In this review, we describe the functional role of RNA polymerase II‐mediated transcription at enhancers and in genome folding. We also highlight the involvement of faulty activation or suppression of enhancer transcription and enhancer‐promoter interaction in cancer development. Noncoding RNA ThymoD (thymocyte differentiation factor) transcription at superenhancers is essential for mouse T‐cell lineage commitment. The cessation of ThymoD transcription abolishes transcription‐mediated demethylation, recruiting looping factors such as the cohesin complex, CTCF, ultimately leading to the phenotype of severe combined immunodeficiency and T‐cell leukemia/lymphoma.

B-cell fate is orchestrated by a series of well-characterized developmental regulators. Here, we found that the onset of B-cell development was accompanied by large-scale changes in DNA cytosine modifications associated with promoters, enhancers, and anchors. These changes were tightly linked to alterations in transcription factor occupancy and nascent RNA (eRNA) transcription. We found that the prepro-B to the pro–B-cell transition was associated with a global exchange of DNA cytosine modifications for polycomb- mediated repression at CpG islands. Hypomethylated regions were found exclusively in the active/permissive compartment of the nucleus and were predominantly associated with regulatory elements or anchors that orchestrate the folding patterns of the genome. We identified superanchors, characterized by clusters of hypomethylated CCCTC-binding factor (CTCF)-bound elements, which were predominantly located at boundaries that define topological associated domains. A particularly prominent hypomethylated superanchor was positioned down-stream of the Ig heavy chain (Igh) locus. Analysis of global formaldehyde–cross-linking studies indicated that the Igh locus superanchor interacts with the VHregion repertoire across vast genomic distances. We propose that the Igh locus superanchor sequesters the VHand DHJHregions into a spatial confined geometric environment to promote rapid first-passage times. Collectively, these studies demonstrate how, in developing B cells, DNA cytosine modifications associated with regulatory and architectural elements affect patterns of gene expression, folding patterns of the genome, and antigen receptor assembly.

Purpose X-linked inhibitor of apoptosis protein (XIAP) deficiency, also known as the X-linked lymphoproliferative syndrome of type 2 (XLP-2), is a rare immunodeficiency characterized by recurrent hemophagocytic lymphohistiocytosis, splenomegaly, and inflammatory bowel disease. Variants in  XIAP  including missense, non-sense, frameshift, and deletions of coding exons have been reported to cause XIAP deficiency. We studied three young boys with immunodeficiency displaying XLP-2-like clinical features. No genetic variation in the coding exons of  XIAP  was identified by whole-exome sequencing (WES), although the patients exhibited a complete loss of XIAP expression. Methods Targeted next-generation sequencing (NGS) of the entire locus of  XIAP  was performed on DNA samples from the three patients. Molecular investigations were assessed by gene reporter expression assays in HEK cells and CRISPR-Cas9 genome editing in primary T cells. Results NGS of  XIAP  identified three distinct non-coding deletions in the patients that were predicted to be driven by repetitive DNA sequences. These deletions share a common region of 839 bp that encompassed the first non-coding exon of  XIAP  and contained regulatory elements and marks specific of an active promoter. Moreover, we showed that among the 839 bp, the exon was transcriptionally active. Finally, deletion of the exon by CRISPR-Cas9 in primary cells reduced XIAP protein expression. Conclusions These results identify a key promoter sequence contained in the first non-coding exon of  XIAP . Importantly, this study highlights that sequencing of the non-coding exons that are not currently captured by WES should be considered in the genetic diagnosis when no variation is found in coding exons.

Background T-cell acute lymphoblastic leukemia (T-ALL) tends to involve central nervous system (CNS) infiltration at diagnosis. However, cases of residual CNS lesions detected at the end of induction and post early intensification have not been recorded in patients with T-ALL. Also, the ratio and prognosis of patients with residual intracranial lesions have not been defined. Case presentation A 9-year-old boy with T-ALL had multiple intracranial tumors, which were still detected post early intensification. To investigate residual CNS lesions, we used 11 C-methionine (MET)-positron emission tomography. Negative MET uptake in CNS lesions and excellent MRD status in bone marrow allowed continuing therapies without hematopoietic cell transplantation. Conclusions In cases with residual lesions on imaging studies, treatment strategies should be considered by the systemic response, direct assessment of spinal fluid, along with further development of noninvasive imaging methods in CNS. Further retrospective or prospective studies are required to determine the prognosis and frequency of cases with residual intracranial lesions after induction therapy.

Familial hemophagocytic lymphohistiocytosis (FHL) is a rare and fatal autosomal recessive immune disorder characterized by uncontrolled activation of T and NK cells, macrophages, and overproduction of inflammatory cytokines. Early hematopoietic cell transplantation (HCT) is required for long-term survival. Current therapy is based on the HLH-94/2004 protocol, but is insufficient to fully control disease activity. This case report describes an infant with FHL type 3 who, despite initial therapy with dexamethasone and etoposide, showed aberrant cytokine levels, including interleukin-18 (IL-18), chemokine ligand 9 (CXCL9), soluble interleukin-2 receptor (sIL-2R), and soluble tumor necrosis factor receptor type II (sTNF-RII). The Janus kinase inhibitor ruxolitinib was therefore coadministered. The patient was treated with dose-adjusted ruxolitinib guided by cytokine profiles, and was successfully prepared for HCT. The results demonstrate the effectiveness and safety of dose-adjusted ruxolitinib as a bridging therapy for FHL, and the value of monitoring cytokine levels, especially IL-18, CXCL9, sIL-2R, and sTNF-RII, as disease-activity markers for FHL.

Background Finding an abdominal mass or hematuria is the initial step in diagnosing Wilms tumor. As the first manifestation of Wilms tumor, it is exceedingly rare for pulmonary tumor embolism to present with cardiac arrest. A case of a patient whose sudden cardiac arrest due to massive pulmonary tumor embolism of Wilms tumor was not responsive to resuscitation is presented. Case presentation The patient was a five-year-old girl who collapsed suddenly during activity in nursery school and went into cardiac arrest in the ambulance. Unfortunately, she was not responsive to conventional resuscitation. A judicial autopsy conducted at the local police department showed the main cause of her sudden cardiac arrest was attributed to multiple pulmonary tumor embolisms of stage IV Wilms tumor. Conclusions Except for one reported case, treatments were not successful in all eight cardiac arrest cases with pulmonary tumor embolism of Wilms tumor. These results indicate that it is challenging not only to make an accurate diagnosis, but also to provide proper specific treatment in the cardiac arrest setting. We propose that flexible triage and prompt transfer to a tertiary hospital are necessary as an oncologic emergency to get such patients to bridging therapy combined with extracorporeal membrane oxygenation or immediate surgical intervention under cardiopulmonary bypass.

Leukocyte adhesion deficiency type I (LAD-I) is a rare autosomal recessive inborn error of immunity (IEI) caused by the defects in CD18, encoded by the ITGB2 gene. LAD-I is characterized by defective leukocyte adhesion to the vascular endothelium and impaired migration of leukocytes. Allogeneic hematopoietic cell transplant (HCT) is the only curative treatment for LAD-I. In an absence of ideal donor for HCT, human leukocyte antigen (HLA)-haploidentical HCT is performed. Posttransplant cyclophosphamide (PT-CY) is a relatively new graft-versus-host disease (GVHD) prophylactic measure and has been increasingly used in HLA-haploidentical HCT for malignant and nonmalignant diseases. However, experience in using PT-CY for rare IEIs, such as LAD-I, is very limited. We report a case of LAD-I successfully treated with HLA-haploidentical HCT with PT-CY. Complete chimerism was achieved, and the patient was cured. Her transplant course was complicated by mild GVHD, cytomegalovirus reactivation and veno-occlusive disease/sinusoidal obstruction syndrome, which were successfully treated. HLA-haploidentical HCT with PT-CY is a safe and effective option for patients with LAD-I when HLA-matched donors are unavailable.

PurposeThe purpose of our study was to compare the safety and efficacy of hematopoietic cell transplantation (HCT) using fludarabine (Flu)-based reduced intensity conditioning (RIC) with busulfan (BU) or melphalan (Mel) for primary immunodeficiency diseases (PID).MethodsWe retrospectively analyzed transplant outcome, including engraftment, chimerism, immune reconstitution, and complications in 15 patients with severe combined immunodeficiency (SCID) and 27 patients with non-SCID PID. The patients underwent Flu-based RIC-HCT with BU (FluBU: 7 SCID, 16 non-SCID) or Mel (FluMel: 8 SCID, 11 non-SCID). The targeted low-dose BU with therapeutic drug monitoring was set to 30 mg hour/L for SCID.ResultsThe 2-year overall survival of all patients was 79.6% and that of patients with SCID in the FluBU and FluMel groups was 100% and 62.5%, respectively. In the FluBU group, all seven patients achieved engraftment, good immune reconstitution, and long-term survival. All five patients receiving umbilical cord blood transplantation achieved complete or high-level mixed chimerism and sufficient specific IgG production. In the FluMel group, six of eight patients achieved complete or high-level mixed chimerism. Viral reactivation or new viral infection occurred in one FluBU group patient and four FluMel group patients. In the non-SCID group, 10 of 11 patients (91%) who received FluMel achieved complete or high-level mixed chimerism but had variable outcomes. Patients with WAS (2/2 patients), NEMO deficiency (2/2 patients), and X-linked hyper IgM syndrome (2/3 patients) who received FluBU achieved complete or high-level mixed chimerism and long-term survival.ConclusionsRIC-HCT with FluBU is a safe and effective strategy for obtaining high-level donor chimerism, immune reconstitution including B cell function, and long-term survival in patients with SCID. In patients with non-SCID PID, the results varied according to the subtype of the disease. Further prospective studies are required to optimize the conditioning regimen for non-SCID PID.

Idiopathic pneumonia syndrome (IPS) is an acute lung complication observed after the early posthematopoietic stem cell transplantation (HSCT) period. Ruxolitinib was effective for a patient with myelodysplastic syndrome who developed severe IPS after second HSCT. No severe adverse effects were observed. Ruxolitinib may be an alternative choice for HSCT‐related IPS. Idiopathic pneumonia syndrome (IPS) is an acute lung complication observed after the early posthematopoietic stem cell transplantation (HSCT) period. Ruxolitinib may be an alternative choice for HSCT‐related IPS.