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STAT2 is a transcription factor activated by type I and III IFNs. We report 23 patients with loss-of-function variants causing autosomal recessive (AR) complete STAT2 deficiency. Both cells transfected with mutant STAT2 alleles and the patients' cells displayed impaired expression of IFN-stimulated genes and impaired control of in vitro viral infections. Clinical manifestations from early childhood onward included severe adverse reaction to live attenuated viral vaccines (LAV) and severe viral infections, particularly critical influenza pneumonia, critical COVID-19 pneumonia, and herpes simplex virus type 1 (HSV-1) encephalitis. The patients displayed various types of hyperinflammation, often triggered by viral infection or after LAV administration, which probably attested to unresolved viral infection in the absence of STAT2-dependent types I and III IFN immunity. Transcriptomic analysis revealed that circulating monocytes, neutrophils, and [CD8.sup.+] memory T cells contributed to this inflammation. Several patients died from viral infection or heart failure during a febrile illness with no identified etiology. Notably, the highest mortality occurred during early childhood. These findings show that AR complete STAT2 deficiency underlay severe viral diseases and substantially impacts survival., Introduction Human type I and III IFNs operate in almost all cell types (1, 2). Type I IFNs (IFN-[alpha]/[beta]) are thought to be secreted by most, if not all, of [...]

Background: More children are coming to heart transplantation on extracorporeal membrane oxygenation (ECMO), or inotropic support and/or with renal impairment. The use of basiliximab, a chimeric monoclonal antibody against CD25 (interleukin 2 receptor alfa) has not been previously reported in critically ill pediatric heart transplant recipients. Basiliximab has potential advantages in the treatment of patients with renal impairment. Methods: Basiliximab was provided to 29 patients (median age 7.8 years; range 0.4–16 years) on ECMO, with renal impairment or receiving intravenous inotropes at transplantation. Children normally received 2 doses on Day 0 and Day 4 after transplantation. Calcineurin inhibitor was provided in low dose or withheld altogether in patients with renal impairment. Flow cytometry was used to monitor CD25. Results: At transplantation, 11 patients were prescribed cyclosporine; the remaining 18 received tacrolimus. All but 4 patients had subtherapeutic levels of calcineurin inhibitor in the first postoperative week. Excluding these 4, there were 19 patients who had more than 4 consecutive doses of calcineurin inhibitor canceled in the first week (median 8 doses; range 3–40 doses). A total of 71 surveillance biopsies were performed, and 4 episodes of severe acute rejection occurred in the first 6 months. In all but one child, the glomerular filtration rate had returned to, or improved on baseline measurement by 1 month after transplantation. Infections rates were low and acceptable. CD25 was undetectable at first assessment, and in all but 1 patient (on ECMO) for at least 2 to 3 weeks thereafter. There were no adverse effects. Conclusions: Basiliximab was well tolerated in this group of very ill children. In children with pre- or postoperative renal dysfunction, where doses of calcineurin inhibitor were low or canceled, basiliximab was associated with a low incidence of rejection. Posttransplant ECMO may reduce the efficacy of basiliximab. These preliminary results are encouraging and now need confirmation in a large, randomized trial. [Copyright &y& Elsevier]

Background. Cytokines regulate many processes in the immune system and have recently been implicated in normal organogenesis. We previously demonstrated that the archetypal inflammatory cytokine tumour necrosis factor-α (TNF-α) is expressed in the murine metanephros, and exogenous TNF-α inhibits nephrogenesis and increases macrophage numbers in vitro (Cale et al., Int J Dev Biol 1998; 42: 663–674). The phenotype seen, with an arrest of ureteric bud branching and failure of mesenchymal to epithelial conversion, is similar to human renal dysplasia. [ABSTRACT FROM PUBLISHER]

EXTL3 regulates the biosynthesis of heparan sulfate (HS), important for both skeletal development and hematopoiesis, through the formation of HS proteoglycans (HSPGs). By whole-exome sequencing, we identified homozygous missense mutations c.1382C>T, c.1537C>T, c.1970A>G, and c.2008T>G in EXTL3 in nine affected individuals from five unrelated families. Notably, we found the identical homozygous missense mutation c.1382C>T (p.Pro461Leu) in four affected individuals from two unrelated families. Affected individuals presented with variable skeletal abnormalities and neurodevelopmental defects. Severe combined immunodeficiency (SCID) with a complete absence of T cells was observed in three families. EXTL3 was most abundant in hematopoietic stem cells and early progenitor T cells, which is in line with a SCID phenotype at the level of early T cell development in the thymus. To provide further support for the hypothesis that mutations in EXTL3 cause a neuro-immuno-skeletal dysplasia syndrome, and to gain insight into the pathogenesis of the disorder, we analyzed the localization of EXTL3 in fibroblasts derived from affected individuals and determined glycosaminoglycan concentrations in these cells as well as in urine and blood. We observed abnormal glycosaminoglycan concentrations and increased concentrations of the non-sulfated chondroitin disaccharide D0a0 and the disaccharide D0a4 in serum and urine of all analyzed affected individuals. In summary, we show that biallelic mutations in EXTL3 disturb glycosaminoglycan synthesis and thus lead to a recognizable syndrome characterized by variable expression of skeletal, neurological, and immunological abnormalities. [ABSTRACT FROM AUTHOR]

Defective V(D)J recombination and DNA double-strand break (DSB) repair severely impair the development of T-lymphocytes and B-lymphocytes. Most patients manifest a severe combined immunodeficiency during infancy. We report 2 siblings with combined immunodeficiency (CID) and immunodysregulation caused by compound heterozygous Artemis mutations, including an exon 1-3 deletion generating a null allele, and a missense change (p.T71P). Skin fibroblasts demonstrated normal DSB repair by gamma-H2AX analysis, supporting the predicted hypomorphic nature of the p.T71P allele. In addition to these two patients, 12 patients with Artemis-deficient CID were previously reported. All had significant morbidities including recurrent infections, autoimmunity, EBV-associated lymphoma, and carcinoma despite having hypomorphic mutants with residual Artemis expression, V(D)J recombination or DSB repair capacity. Nine patients underwent stem cell transplant and six survived, while four patients who did not receive transplant died. The progressive nature of immunodeficiency and genomic instability accounts for poor survival, and early HSCT should be considered., (© 2013 Elsevier Inc. All rights reserved.)

The optimal approach to stem cell transplantation in children with immunodeficiency who lack a matched family donor is controversial. Unrelated donor stem cell transplantation gives equivalent outcome to mismatched family donor stem cell transplantation in severe combined immunodeficiency, whereas unrelated donors may be preferable in non-severe combined immunodeficiency children. However, unrelated donor stem cell transplantation with conventional conditioning regimens has been associated with significant treatment-related toxicity, particularly in non-severe combined immunodeficiency patients with preexisting organ dysfunction. We report the outcome of a series of 33 consecutive unrelated donor transplantations performed at our center in children with primary immunodeficiency using a reduced-intensity conditioning regimen between 1998 and 2001. We have compared these outcomes with a retrospective control cohort of 19 patients who underwent transplantation with myeloablative conditioning between 1994 and 1998. All children in both groups had primary engraftment. There was no statistical difference in the speed of immune reconstitution or incidence of graft-versus-host disease between the 2 groups. Overall survival was significantly better in the reduced-intensity conditioning group: 31 (94%) of 33 patients survived, compared with 10 (53%) of 19 in the myeloablative conditioning group (P = .014). We conclude that the reduced-intensity conditioning regimen results in improved survival and reduced transplantation-related mortality compared with myeloablative conditioning in high-risk patients undergoing unrelated donor transplantation.