Inborn errors of immunity (IEI) are a genetically heterogeneous group of disorders with a broad clinical spectrum. Identification of molecular and functional bases of these disorders is important for diagnosis, treatment and an understanding of the human immune response. We identified six unrelated males with neutropenia, infections, lymphoproliferation, humoral immune defects, and in some cases bone marrow failure associated with three different variants in the X-linked gene TLR8, encoding the endosomal Toll-like receptor 8 (TLR8). Interestingly, five patients had somatic variants in TLR8 with less than 30% mosaicism, suggesting a dominant mechanism responsible for the clinical phenotype. Mosaicism was also detected in skin-derived fibroblasts in three patients, demonstrating that mutations were not limited to the hematopoietic compartment. All patients had refractory chronic neutropenia, and three patients underwent allogeneic hematopoietic cell transplantation. All variants conferred gain-of-function to TLR8 protein, and immune phenotyping demonstrated a pro-inflammatory phenotype with activated T cells and elevated serum cytokines associated with impaired B cell maturation. Differentiation of myeloid cells from patient-derived induce pluripotent stem cells demonstrated increased responsiveness to TLR8. Together these findings demonstrate that gain-of-function variants in TLR8 lead to a novel childhood-onset IEI with lymphoproliferation, neutropenia, infectious susceptibility, B and T cell defects, and in some cases bone marrow failure. Somatic mosaicism is a prominent molecular mechanism of this new disease.
Background: Antiretroviral therapy (ART) scale-up in resource-limited countries, with limited capacity for CD4 and HIV viral load monitoring, presents a unique challenge. We determined the effectiveness of first-line ART in a real world pediatric HIV clinic and explored associations between readily obtainable patient data and the trajectories of change in CD4 count and HIV viral load. Methods: We performed a longitudinal study of a cohort of HIV-infected children initiating ART at the Korle-Bu Teaching Hospital Pediatric HIV clinic in Accra, Ghana, aged 0-13 years from 2009-2012. CD4 and viral load testing were done every 4 to 6 months and genotypic resistance testing was performed for children failing therapy. A mixed linear modeling approach, combining fixed and random subject effects, was employed for data analysis.
Summary:The risk of Epstein-Barr virus lymphoproliferative disease (EBV-LPD) increases with the use of highly immunosuppressive therapies. Allogeneic BMT, especially supported by T-cell-depleted stem cell products, is a risk factor for EBV-LPD. Although the risk of EBV-LPD after autologous transplantation is low, case reports of this complication in the autologous setting exist. We report a higher incidence than previously described of EBV-LPD in children undergoing sequential high-dose chemotherapy supported with CD34 selected peripheral blood stem cells (CD34 þ PBSC). The median time to LPD after tandem transplant was 3 months (range 1-5 months). Five patients out of 156 (3.5%) developed EBV-LPD while enrolled on two trials of tandem autologous SCT in high-risk pediatric malignancies. Both studies employed five cycles of induction therapy, followed by tandem autologous PBSC transplants. In all, 108 out of 156 patients received CD34 þ PBSC; 48 received unselected PBSC. All patients contracting LPD were from the CD34 selected group. Treatment of EBV-LPD included rituximab in four out of five patients, IVIg in two out of five patients, and gancyclovir in two out of five patients. EBV-LPD resolved in four out of five patients. We conclude that the combination of tandem SCT and CD34 selection may have increased immunosuppression in these patients to a point where there is an elevated risk of EBV-LPD.
BackgroundHIV-infected children in sub-Saharan Africa may be at a high risk of staying on a failing first-line regimen and developing drug-resistance HIV variants due to lack of routine viral load monitoring. We investigated whether cumulative viral load, measured as viremia copy-years (VCY) could predict morbidity in a setting where viral load is not routinely monitored.MethodsThis was a single-center prospective observational longitudinal study of HIV-infected children initiating antiretroviral therapy (ART) at the Pediatric HIV/AIDS Care program at Korle-Bu Teaching Hospital in Accra, Ghana. The main outcome was morbidity measured as frequency of hospitalizations, opportunistic infections, and outpatient sick visits. The main explanatory variable was viral load measured as VCY.ResultsThe study included 140 children who initiated ART between September 2009 and May 2013 and had at least 2 viral load measurements. There were 184 hospitalizations, with pneumonia being the most common cause (22.8 %). A total of 102 opportunistic infections was documented, with tuberculosis being the most common opportunistic infection (68 %). A total of 823 outpatient sick visits was documented, with upper respiratory infections (14.2 %) being the most common cause. Forty-four percent of our study participants had >4 log10 VCY. Children in this sub-cohort had a higher frequency of sick visits compared with those with <4 log10 VCY (p = 0.03). Only 6.5 % of children with >4 log10 VCY had been identified as treatment failure using WHO clinical and immunological treatment failure criteria.ConclusionsHigh level of cumulative viral load may translate to virological failure and subsequent increased all-cause morbidity. Our finding of potential utility of VCY in pediatrics warrants further investigations. VCY may be a good alternate to routine viral load measurement as its determination may be less frequent and could be personalized to save cost.
Two children presented with a history of fever and rash. Lab values revealed pancytopenia, elevated ferritin, coagulopathy, and elevated triglycerides. Both children quickly developed respiratory distress and hypotension requiring admission to the ICU. Bone marrow biopsies revealed hemophagocytosis. Studies for Ehrlichia returned positive. The patients were started on doxycycline and treated for hemophagocytic lymphohistiocytosis (HLH). Each made a full recovery. In both patients, testing for MUNC and perforin genes were found to have no mutation. These two cases demonstrate the importance of considering Ehrlichiosis as a possible trigger of HLH.
During chemotherapy for bilineal leukemia, a 6-month-old infant presented with a necrotizing skin and soft-tissue infection of the chest wall due to Rhizopus sp. Successful outcome was achieved by systemically administered liposomal amphotericin B and local wound control with the novel administration of topical deoxycholate amphotericin B and surgical resection.
This report is the first to describe acute deferasirox-induced nephrotoxicity, and the application of plasmapheresis that, ultimately, did not change the typical time to recovery.
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