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IntroductionLynch syndrome (LS) and constitutional mismatch repair deficiency (CMMRD) are hereditary cancer syndromes associated with mismatch repair (MMR) deficiency. Tumours show microsatellite instability (MSI), also reported at low levels in non-neoplastic tissues. Our aim was to evaluate the performance of high-sensitivity MSI (hs-MSI) assessment for the identification of LS and CMMRD in non-neoplastic tissues.Materials and methodsBlood DNA samples from 131 individuals were grouped into three cohorts: baseline (22 controls), training (11 CMMRD, 48 LS and 15 controls) and validation (18 CMMRD and 18 controls). Custom next generation sequencing panel and bioinformatics pipeline were used to detect insertions and deletions in microsatellite markers. An hs-MSI score was calculated representing the percentage of unstable markers.ResultsThe hs-MSI score was significantly higher in CMMRD blood samples when compared with controls in the training cohort (pMSH2 carriers (n=5) compared with MSH6 carriers (n=15). The hs-MSI analysis did not detect a difference between LS and control blood samples (p=0.564).ConclusionsThe hs-MSI approach is a valuable tool for CMMRD diagnosis, especially in suspected patients harbouring MMR variants of unknown significance or non-detected biallelic germline mutations.

Background: Recent findings strongly support hematopoietic stem cell transplantation (HSCT) in patients with severe presentation of LPS-responsive beige-like anchor protein (LRBA) deficiency, but long-term follow-up and survival data beyond previous patient reports or meta-reviews are scarce for those patients who do not receive a transplant. Objective: This international retrospective study was conducted to elucidate the longitudinal clinical course of patients with LRBA deficiency who do and do not receive a transplant. Method: We assessed disease burden and treatment responses with a specially developed immune deficiency and dysregulation activity score, reflecting the sum and severity of organ involvement and infections, days of hospitalization, supportive care requirements, and performance indices. Results: of 76 patients with LRBA deficiency from 29 centers (median follow-up, 10 years; range, 1-52), 24 underwent HSCT from 2005 to 2019. the overall survival rate after HSCT (median follow-up, 20 months) was 70.8% (17 of 24 patients); all deaths were due to nonspecific, early, transplant-related mortality. Currently, 82.7% of patients who did not receive a transplant (43 of 52; age range, 3-69 years) are alive. of 17 HSCT survivors, 7 are in complete remission and 5 are in good partial remission without treatment (together, 12 of 17 [70.6%]). in contrast, only 5 of 43 patients who did not receive a transplant (11.6%) are without immunosuppression. Immune deficiency and dysregulation activity scores were significantly lower in patients who survived HSCT than in those receiving conventional treatment (P = .005) or in patients who received abatacept or sirolimus as compared with other therapies, and in patients with residual LRBA expression. Higher disease burden, longer duration before HSCT, and lung involvement were associated with poor outcome. Conclusion: the lifelong disease activity, implying a need for immunosuppression and risk of malignancy, must be weighed against the risks of HSCT., Styrian Children's Cancer Aid Foundation; Slovenian Research AgencySlovenian Research Agency - Slovenia [P3-0343]; Jonas S_oderquist Foundation; Scientific and Technological Research Council of TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [217S847, 318S202]; Deutsche Forschungsgemeinschaft under Germany's Excellence StrategyGerman Research Foundation (DFG) [390939984, 39087428]; E-Rare program of the European Union by the Deutsche ForschungsgemeinschaftGerman Research Foundation (DFG) [GR1617/14-1/iPAD]; Netzwerke Seltener Erkrankungen of the German Ministry of Education and Research [GAIN_ 01GM1910A]; Finnish Foundation for Pediatric Research and Pediatric Research Center, HUS Helsinki University Hospital; Graduate Research Training Scholarship of the Australian government; Hadassah Australia; ERN-RITA network [739543], M.G. Seidel and the Research Unit for Pediatric Hematology and Immunology are supported in part by the Styrian Children's Cancer Aid Foundation. M. Avbeli Stefanija was supported by the Slovenian Research Agency (grant P3-0343). H. Abolhassani was supported by the Jonas S_oderquist Foundation. S. Baris was supported by the Scientific and Technological Research Council of Turkey for the diagnosis of patients with LRBA deficiency (grants 217S847 and 318S202). B. Grimbacher receives support through the Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy (CIBSS-EXC-2189-Project ID 390939984 and RESIST-EXC 2155-Project ID 39087428); through the E-Rare program of the European Union, managed by the Deutsche Forschungsgemeinschaft (grant GR1617/14-1/iPAD); and through the Netzwerke Seltener Erkrankungen of the German Ministry of Education and Research (grant GAIN_ 01GM1910A). M.R.J. Sepp_anen was supported by the Finnish Foundation for Pediatric Research and Pediatric Research Center, HUS Helsinki University Hospital. I. Meyts is a member of the ERN-RITA network (project identification number 739543). B. Shadur is supported by a Graduate Research Training Scholarship of the Australian government and by Hadassah Australia.

Background Data on anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis are scarce in children. The current study is aimed at describing the clinical features and outcomes of childhood-onset ANCA-associated vasculitis (AAV). Methods We conducted a retrospective French multicentre study involving patients in whom AAV was diagnosed before the age of 18 years. Inclusion criteria were (i) granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) according to classification criteria of the European League Against Rheumatism/Paediatric Rheumatology European Society, and (ii) ANCA positivity. Patient and renal survival were analysed. Results Among 66 children included, 80% were female, 42% had GPA and 58% MPA including renal-limited vasculitis, 67% were pANCA+ and 33% cANCA+. The mean incidence of reported cases increased to 0.45 per million children/year in the period 2006-10. Median age at diagnosis was 11.5 years, and median time to diagnosis was 1 month. Initial symptoms included fever and fatigue (79%), skin lesions (41%), arthritis (42%), pulmonary (45%) and renal involvement (88%). Clinical features were similar between GPA and MPA with the exception of upper airway impairment (28%) specific of GPA. Ninety percent of the patients achieved remission after induction treatment. After a median follow-up of 5.2 years, 4 patients (6%) died, corresponding to a mortality rate of 1.2 per 100 person-years, and 22 patients (34%) developed end-stage renal disease (ESRD). Renal survival was 74, 70 and 59% at 1, 5 and 10 years, respectively. In a multivariable Cox regression model, baseline glomerular filtration rate, ethnic origin, histopathological classification and era of treatment were associated with the occurrence of ESRD. Relapse-free survival was 57% at 5 years and 34% at 10 years of follow-up. Patient and renal outcome did not significantly differ between GPA and MPA. Conclusion Childhood-onset AAV is a rare disease characterized by female predominance, delayed diagnosis, frequent renal impairment and a high remission rate. Baseline GFR and new histopathological classification system are strong predictors of ESRD. Renal survival in childhood AAV has improved over time.

OBJECTIVES:Clinical data are lacking on optimal levels of specific antipneumococcal antibodies (PnPsAbs) in patients with primary immunodeficiency (PID) receiving intravenous immunoglobulin (IVIG) replacement. Objectives were to conduct a prospective multicenter study providing data on total immunoglobulin G (IgG) and peak/trough levels of PnPsAbs specifically targeting the 16 most prevalent pneumococcal serotypes in IVIG-treated children with PID; to compare trough PnPsAb levels with those measured in healthy adults and the IVIG product; and to evaluate PnPsAb protection correlates with thresholds based on World Health Organization.METHODS:Patients received 7 consecutive IVIG infusions. Total IgG and PnPsAb levels were determined on plasma samples obtained before and after infusion.RESULTS:Twenty-two children with PID were treated with IVIG (mean weekly dose: 0.10 g/kg). The mean trough and peak levels of total IgG were 7.77 and 13.93 g/L, respectively. Trough and peak geometric mean concentrations and distribution curves differed between serotypes and showed wide dispersion (0.17–7.96 µg/mL). In patients (89%–100%), antibodies against most serotypes reached trough levels ≥0.2 µg/mL, a threshold considered protective against invasive pneumococcal infection. For several serotypes, trough levels reached ≥1.0 to 1.3 µg/mL, the level found in adults. Trough geometric mean concentrations correlated well with the PnPsAb contents of the IVIG product.CONCLUSIONS:In IVIG-treated children with PID, protective PnPsAb levels for most pathogenic serotypes were obtained. A correlation was observed between PnPsAb levels in patients and in the IVIG product. This offers the potential to improve infection prevention by adapting the IVIG product and dose according to epidemiology.

International audience; BACKGROUND: Anakinra pharmacokinetics and pharmacodynamics were investigated in children and adolescents treated for systemic-onset juvenile idiopathic arthritis (SJIA) and autoinflammatory syndromes. METHODS: Anakinra was given subcutaneously at doses between 2 and 10 mg/kg (maximum 100 mg) per day. Anakinra concentrations were recorded in patients, as well as C-reactive protein (CRP) levels, on different occasions. The data were fitted to a pharmacokinetic-pharmacodynamic model via a population approach using Monolix. RESULTS: A total of 87 children and adolescents, 8 months to 21 years old, were available for pharmacokinetic evaluation. A one compartment model with linear absorption and elimination described the pharmacokinetics. Taking into account bodyweight to explain variations in apparent clearance (CL/F) and distribution volume (V/F) significantly reduced the associated between-subject and between-occasion variabilities. The final estimates were 6.24 L/h/70 kg and 65.2 L/70 kg for CL/F and V/F respectively. A mixture pharmacodynamic model described the CRP level change during anakinra treatment for the SJIA patients with 2 subpopulations, patients with high baseline and large CRP decrease and patients with low baseline and small CRP decrease followed by a re-increase in CRP levels. There was no significant effect of the combined anti-inflammatory treatment. The proportion of patients for which the development of a resistance to treatment was significant was 62% and the corresponding time was approximately 60 days CONCLUSIONS: Based on effects in SJIA, a prospective dosage adjustment was proposed based on a 0.4 mg/L Css target in order to obtain a CRP decrease to 10 mg/L or below.

Autoimmune lymphoproliferative syndrome (ALPS) is a genetic disorder characterized by early-onset, chronic, nonmalignant lymphoproliferation, autoimmune manifestations, and susceptibility to lymphoma. The majority of ALPS patients carry heterozygous germline (ALPS-FAS) or somatic mutations (ALPS-sFAS) of the TNFRSF6 gene coding for FAS. Although the clinical features of ALPS have been described previously, long-term follow-up data on morbidity and mortality are scarce. We performed a retrospective analysis of clinical and genetic features of 90 ALPS-FAS and ALPS-sFAS patients monitored over a median period of 20.5 years. Heterozygous germline mutations of TNFRSF6 were identified in 83% of probands. Somatic TNFRSF6 mutations were found in 17% of index cases (all located within the intracellular domain of FAS). Sixty percent of the ALPS-FAS patients with mutations in the extracellular domain had a somatic mutation affecting the second allele of TNFRSF6; age at onset was later in these patients. No other genotype-phenotype correlations could be found. Long-term analysis confirmed a trend toward spontaneous remission of lymphoproliferation in adulthood but mixed outcomes for autoimmune manifestations. We observed significant and potentially life-threatening disease and treatment-related morbidity, including a high risk of sepsis after splenectomy that calls for careful long-term monitoring of ALPS patients. We also noted a significantly greater occurrence of disease-related symptoms in male than in female patients.

MKD causes hyper-IgD syndrome and mevalonic aciduria. Disease severity and clinical phenotype has not yet been linked to specific mutations. In this study, we intended to review clinical presentation and outcome of pediatric and adult patients. 40 patients were identified through MVK mutation database in one central reference laboratory and physicians' networking. Medical charts were reviewed (21/40) or questionnaires were filled in by treating physician (19/40). Follow-up ranged from 2 years to 60 years. First symptoms occurred before age 2 in 90% of patients. Main clinical features were fever (100%), abdominal pain (92%), diarrhea (88%), enlarged lymph nodes (88%), skin rash (86%), arthralgias (85%), arthritis (43%), growth delay (33%), CNS white matter involvement (7,5%) and macrophage activation syndrome (5%). We recorded 3 disease-related deaths. IgD level ranged from normal (

Varicella-Zoster (VZV) virus, Cytomegalovirus (CMV) and Epstein Barr virus (EBV) infections may have a severe course in patients on immunosuppressive treatments. Data in Juvenile Idiopathic Arthritis (JIA) patients on biologics are still limited.

Results Forty-seven children were included, 15 (32%) with WG and 32 (68%) with MPA, 77% children were pANCA +/MPO. Female predominated (85%), the median age at diagnosis was 10 years (2-16), and average time to diagnosis was 8 months (0-58). 53% children presented with fever, 77% with deterioration of general condition. 91% had renal involvement. Among them 91% had proteinuria, 44% had hypertension, 79% had renal failure of whom one third presented with end-stage renal disease (ESRD), 22% had gross hematuria and 82% microscopic hematuria. Half the patients showed pulmonary involvement (alveolar hemorrhage for 77% and nodules for 18%). 28% presented with upper airways involvement, 38% with cutaneous lesions (67% purpura), and 19% with arthritis. Few had digestive, ophthalmic or CNS involvement. After an average follow-up of 5 years (2m24y), 3 patients (6%) died. 60% were considered in remission (partial or total) after induction treatment and 77% at last follow-up. 33% of children with initial renal involvement developed chronic kidney disease, half of them progressed to ESRD. 43% needed dialysis and 29% underwent a renal transplantation.