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Background Several cases of idiopathic nephrotic syndrome (INS) relapse following the administration of coronavirus disease 2019 (COVID-19) vaccines have recently been reported, raising questions about the potential relationship between the immune response to COVID-19 vaccination and INS pathogenesis. Methods We performed a retrospective multicentre survey describing the clinical and biological characteristics of patients presenting a relapse of INS after COVID-19 vaccination, with an assessment of outcome under treatment. Results We identified 25 patients (16 men and 9 women) presenting a relapse within 1 month of a COVID-19 vaccine injection. The glomerular disease was of childhood onset in half of the patients and most patients (21/25) had received at least one immunosuppressive drug in addition to steroids for frequently relapsing or steroid-dependent nephrotic syndrome (NS). All patients were in a stable condition at the time of injection and 11 had no specific treatment. In five patients, the last relapse was reported >5 years before vaccine injection. The Pfizer-BioNTech (BNT162b2) vaccine was used in 80% of the patients. In 18 cases, INS relapse occurred after the first injection, a mean of 17.5 days after vaccination. A second injection was nevertheless administered in 14 of these patients. Five relapses occurred after administration of the second dose and two relapses after the administration of the third dose. All but one of the patients received steroids as first-line treatment, with an additional immunosuppressive agent in nine cases. During follow-up, complete remission was achieved in 21 patients, within 1 month in 17 cases. Only one patient had not achieved at least partial remission after 3 months of follow-up. Conclusions This case series suggests that, in rare patients, COVID-19 vaccination may trigger INS relapse that is generally easy to control. These findings should encourage physicians to persuade their patients to complete the COVID-19 vaccination schedule.

Primary hyperoxaluria type 1 (PH1) is a rare, progressive, genetic disease with limited treatment options. We report the efficacy and safety of lumasiran, an RNA interference therapeutic, in infants and young children with PH1.This single-arm, open-label, phase 3 study evaluated lumasiran in patients aged6 years with PH1 and an estimated glomerular filtration rate45 mL/min/1.73 mAll patients (N = 18) completed the 6-month primary analysis period. Median age at consent was 50.1 months. Least-squares mean percent reduction in spot UOx:Cr was 72.0%. At month 6, 50% of patients (9/18) achieved spot UOx:Cr ≤1.5× upper limit of normal. Least-squares mean percent reduction in plasma oxalate was 31.7%. The most common treatment-related adverse events were transient, mild, injection-site reactions.Lumasiran showed rapid, sustained reduction in spot UOx:Cr and plasma oxalate and acceptable safety in patients aged6 years with PH1, establishing RNA interference therapies as safe, effective treatment options for infants and young children.

Lumasiran, a sub-cutaneous RNA-interference therapy, has been recently approved for primary hyperoxaluria type 1 (PH1), with doses and intervals according to body weight. Little is known as to its use in infants; the aim of this study was to describe treatment outcome in 3 infants who received lumasiran therapy before 2 years of age.Patient 1 was diagnosed antenatally and received lumasiran from day 9. According to the product information template (PIT), he received monthly lumasiran (3 times at 6 mg/kg, then 3 mg/kg), with hyperhydration and potassium citrate. Despite decreased plasma oxalate levels, persistent normal kidney function, and good tolerance, kidney ultrasound performed after 2 months found nephrocalcinosis, without normalization of urinary oxalate (UOx). The dose was increased back to 6 mg/kg, inducing a normalization in UOx. Nephrocalcinosis started to improve at month 10. Patient 2 was diagnosed at 2.5 months (acute kidney failure); nephrocalcinosis was present from diagnosis. She received monthly lumasiran (6 mg/kg), with progressive decrease in UOx and substantial improvement in kidney function but stable nephrocalcinosis after 9 injections. Patient 3 was diagnosed fortuitously (nephrocalcinosis) at 3.5 months and received lumasiran before genetic diagnosis, leading to decreased UOx and maintenance of normal kidney function. Nephrocalcinosis improved after 5 injections.This report presents the youngest children treated with lumasiran worldwide. Lumasiran seems effective without side effects in infants but does not completely prevent the onset of nephrocalcinosis in the most severe forms. Higher doses than those proposed in the PIT might be required because of hepatic immaturity.

Primary hyperoxalurias are rare disease with autosomal recessive inheritance; they often lead to kidney failure and can lead to life-threatening conditions, especially in early onset forms. There are three types, responding to distinct enzyme deficits. Type 1 represents 85% of cases and results from an enzyme deficiency (alanine-glyoxylate aminotransferase) in the peroxisomes of the liver, causing hyperoxaluria leading to urolithiasis with or without nephrocalcinosis. As glomerular filtration decreases, a systemic overload appears and spares no organ. Treatment has hitherto been based on combined liver and kidney transplantation, with significant mortality and morbidity. The recent introduction of interfering RNA treatments opens up new perspectives. By blocking an enzymatic synthesis (glycolate oxidase or lacticodehydrogenase a) upstream of the deficit that causes the disease, oxaluria normalizes and the tolerance of the drug (administered by injection every 1 to 3 months) is good. This strategy will help prevent kidney failure in patients treated early and avoid liver transplantation in those who are diagnosed at an advanced stage of kidney failure.

The anti-CD20 rituximab is often used in the treatment of children with steroid-resistant nephrotic syndrome or EBV-induced post-transplant lymphoproliferative disorder. This single-center series reports the use of rituximab as induction therapy in pediatric kidney transplantation.Four children who received rituximab as induction therapy for kidney transplantation since 2016 were retrospectively analyzed. Clinical and laboratory data were extracted from medical records.The patients (2 boys and 2 girls) were aged from 6.1 to 11.9 years and were treated with rituximab on the day of the transplantation procedure; all the transplants came from deceased donors. In all patients, rituximab was used because of positive EBV viral loads before kidney transplantation. Viral loads remained undetectable for the first 6 months after the transplantation procedure and remained below the 4.5 log threshold thereafter. After a median follow-up of 2.3 years, none of the patients displayed rejection or de novo donor-specific antibodies; the glomerular filtration rate remained above 70 ml/min/1.73 mThe results suggest that rituximab can be used as induction therapy to prevent EBV replication and its complications in case of positive viral load prior to kidney transplantation.

BACKGROUND AND AIMS Primary hyperoxaluria type 1 (PH1) is a rare genetic disorder characterised by hepatic oxalate overproduction that leads to progressive kidney disease. As kidney function declines, oxalate elimination is compromised and plasma oxalate (POx) increases, leading to systemic oxalosis. In chronic kidney disease (CKD) stages 3b–5, elevated POx is directly related to the pathophysiology of oxalosis, and reduction of POx is a relevant clinical trial endpoint. Lumasiran, an RNA interference therapeutic designed to reduce hepatic oxalate production, is indicated for the treatment of PH1 in all age groups. Data from the ILLUMINATE-C trial (EudraCT: 2019–0 013 346-17) demonstrated substantial reductions in POx and acceptable safety in patients with PH1 with impaired kidney function, including patients on haemodialysis (HD), who received lumasiran for 6 months. In Cohorts A (no HD) and B (on HD), respectively, lumasiran led to 33.33% [95% confidence interval (95% CI): −15.16 to 81.82] and 42.43% (95% CI: 34.15–50.71) least-squares (LS) mean reductions in POx from baseline to Month 6 (the primary endpoint). Here, we present METHOD ILLUMINATE-C is an ongoing Phase 3, single-arm study with two cohorts, Cohort A (N = 6; no HD at study start) and Cohort B (N = 15; on HD). The 6-month primary analysis period is followed by an extension period (EP) of up to 54 months. Key inclusion criteria include genetically confirmed PH1, eGFR ≤ 45 mL/min/1.73 m2 and POx ≥ 20 μmol/L. Patients received weight-based dosing of subcutaneous lumasiran. Outcomes of interest for the current analysis included assessments of cardiac oxalosis using echocardiography, medullary nephrocalcinosis by kidney ultrasound, kidney stone events and burdensome symptoms of PH1. RESULTS All 21 patients [43% female; 76% white; median age 8 (range 0–59) years] completed the 6-month primary analysis period. Among patients with abnormal left ventricular ejection fraction (LVEF; abnormal defined as LVEF CONCLUSION Lumasiran treatment resulted in substantial reductions in POx in patients of all ages with PH1 and advanced kidney disease. The observations regarding cardiac measures that reflect systemic oxalosis, together with the kidney stone event and nephrocalcinosis results, are consistent with mobilisation of oxalate from systemic stores. Data on these long-term outcomes will continue to be collected and further evaluated in the EP. These results, along with previous reports from ILLUMINATE-A and ILLUMINATE-B, provide evidence supporting the effectiveness of lumasiran across the full spectrum of patients affected by PH1.

WOS: 000530171600001 PubMed: 32367310 Background Secondary hyperparathyroidism (SHPT) may persist after renal transplantation (RTx), inducing hypophosphatemia and hypercalcemia that precludes the use of vitamin D analogs. The calcimimetic cinacalcet improved plasma calcium and parathyroid hormone (PTH) levels in randomized controlled trials in adults after RTx, but pediatric data are scarce. Methods In this retrospective study, we analyzed 20 pediatric patients from the Cooperative European Paediatric Renal TransplAnt Initiative (CERTAIN) Registry who received cinacalcet after RTx. The results are presented as median and interquartile range (25th-75th percentile). Results At 13.7 (11.0-16.5) years of age, 20 pediatric patients received a renal allograft. Cinacalcet was introduced at 0.4 (0.3-2.7) years post-transplant at an estimated glomerular filtration rate (eGFR) of 50 (34-66) mL/min/1.73 m(2), plasma calcium of 2.58 (2.39-2.71) mmol/L, age-standardized (z score) phosphate of - 1.7 (- 2.7-- 0.4), and PTH of 136 (95-236) ng/L. The starting dose of cinacalcet was 0.5 (0.3-0.8) mg/kg per day, with a maximum dose of 1.1 (0.5-1.3) mg/kg per day. With a follow-up of 3.0 (1.5-3.6) years on cinacalcet therapy, eGFR remained stable; PTH levels decreased to 66 (56-124) ng/L at the last follow-up (p = 0.015). One patient displayed hypocalcemia (1.8 mmol/L). Cinacalcet was withdrawn in three patients (hypocalcemia, parathyroidectomy, incompliance). Nephrocalcinosis of the graft was not reported. Conclusions This pilot study suggests that cinacalcet as off-label therapy for SHPT after pediatric RTx is efficacious in controlling post-transplant SHPT with acceptable tolerability. Continuing cinacalcet even with normal PTH can lead to dangerous life-threatening hypocalcemia. Therefore, at each subsequent visit, the need to continue cinacalcet must be assessed. Dietmar Hopp Stiftung; European Society for Paediatric Nephrology (ESPN); German Society for Paediatric Nephrology (GPN); AstellasAstellas Pharmaceuticals; NovartisNovartis The authors received financial support from the CERTAIN Registry by a grant from the Dietmar Hopp Stiftung, the European Society for Paediatric Nephrology (ESPN), and the German Society for Paediatric Nephrology (GPN), and by grants from the pharmaceutical companies Astellas and Novartis.

Introduction: Primary hyperoxaluria type 1 (PH1) is a rare genetic disease caused by hepatic overproduction of oxalate, leading to kidney stones, nephrocalcinosis, kidney failure, and systemic oxalosis. In the 6-month double-blind period (DBP) of ILLUMINATE-A, a phase 3, randomized, placebo-controlled trial in patients with PH1 ≥6 years old, treatment with lumasiran, an RNA interference therapeutic, led to substantial reductions in urinary oxalate (UOx) levels. Methods: We report data to month 12 in the extension period (EP) of ILLUMINATE-A, including patients who continued lumasiran (lumasiran/lumasiran) or crossed over from placebo to lumasiran (placebo/lumasiran). Results: In the lumasiran/lumasiran group (n = 24), the reduction in 24-hour UOx level was sustained to month 12 (mean reduction from baseline, 66.9% at month 6; 64.1% at month 12). The placebo/lumasiran group (n = 13) had a similar time course and magnitude of 24-hour UOx reduction (mean reduction, 57.3%) after 6 months of lumasiran. Kidney stone event rates seemed to be lower after 6 months of lumasiran in both groups compared with the 12 months before consent, and this reduction was maintained at month 12 in the lumasiran/lumasiran group. At study start, 71% of patients in the lumasiran/lumasiran group and 92% in the placebo/lumasiran group had nephrocalcinosis. Nephrocalcinosis grade improved after 6 months of lumasiran in the lumasiran/lumasiran and placebo/lumasiran groups (13% and 8% of patients, respectively). After an additional 6 months of lumasiran, 46% of patients had improvement in nephrocalcinosis grade within the lumasiran/lumasiran group. Estimated glomerular filtration rate (eGFR) remained stable during the course of lumasiran treatment. The most common adverse events (AEs) related to lumasiran were mild, transient injection-site reactions (ISRs). Conclusion: Long-term lumasiran treatment enabled sustained lowering of UOx levels with acceptable safety and encouraging results on clinical outcomes.

Background Primary hyperoxaluria type 1 (PH1) is a rare genetic disease that causes progressive kidney damage and systemic oxalosis due to hepatic overproduction of oxalate. Lumasiran demonstrated efficacy and safety in the 6-month primary analysis period of the phase 3, multinational, open-label, single-arm ILLUMINATE-B study of infants and children Methods Of the 18 patients enrolled in the 6-month primary analysis period, all entered the EP and completed ≥ 6 additional months of lumasiran treatment (median (range) duration of total exposure, 17.8 (12.7–20.5) months). Results Lumasiran treatment was previously reported to reduce spot urinary oxalate:creatinine ratio by 72% at month 6, which was maintained at 72% at month 12; mean month 12 reductions in prespecified weight subgroups were 89%, 68%, and 71% for patients weighing Conclusions Lumasiran treatment provided sustained reductions in urinary and plasma oxalate through month 12 across all weight subgroups, with an acceptable safety profile, in infants and young children with PH1. Graphical abstract A higher resolution version of the Graphical abstract is available as Supplementary information

C3 glomerulopathy (C3G) is a rare complement-mediated disease. Specific treatments are not yet available and factors predictive of kidney survival such as age, kidney function and proteinuria are not specific to C3G. The prognostic value of biomarkers of complement activation, which are pathognomonic of the diseases, remains unknown. In a large cohort of 165 patients from the French National registry, we retrospectively assess the prognostic value of C3, soluble C5b-9 (sC5b-9), C3 nephritic factor, and rare disease-predicting variants in complement genes in predicting clinical outcome of patients. By multivariate analysis age (adult onset), reduced kidney function (defined by estimated glomerular filtration rate under 60ml/min) and presence of rare disease-predicting variants in complement genes predicted risk of progression to kidney failure. Moreover, by multivariate analysis, normal C3/high sC5b-9 levels or low C3/normal sC5b-9 levels remained independently associated with a worse kidney prognosis, with the relative risk 3.7- and 8-times higher, respectively. Subgroup analysis indicated that the complement biomarker profiles independently correlated to kidney prognosis in patients with adult but not pediatric onset. In this subgroup, we showed that profiles of biomarkers C3 and/or sC5b-9 correlated with intra glomerular inflammation and may explain kidney outcomes. In children, only the presence of rare disease-predicting variants correlated with kidney survival. Thus, in an adult population, we propose a three-point C3G prognostic score based on biomarker profiles at risk, estimated glomerular filtration rate at presentation and genetic findings, which may help stratify adult patients into subgroups that require close monitoring and more aggressive therapy.

Cardiac involvement is a known but rare complication of pediatric hemolytic uremic syndrome (HUS). We conducted a nationwide observational, retrospective case-control study describing factors associated with the occurrence of myocarditis among HUS patients.Cases were defined as hospitalized children affected by any form of HUS with co-existent myocarditis in 8 French Pediatric Intensive Care Units (PICU) between January 2007 and December 2018. Control subjects were children, consecutively admitted with any form of HUS without coexistent myocarditis, at a single PICU in Lyon, France, during the same time period.A total of 20 cases of myocarditis were reported among 8 PICUs, with a mean age of 34.3 ± 31.9 months; 66 controls were identified. There were no differences between the two groups concerning the season and the typical, Shiga toxin-producing Escherichia coli (STEC-HUS), or atypical HUS (aHUS). Maximal leukocyte count was higher in the myocarditis group (29.1 ± 16.3G/L versus 21.0 ± 9.9G/L, p = 0.04). The median time between admission and first cardiac symptoms was of 3 days (range 0-19 days), and 4 patients displayed myocarditis at admission. The fatality rate in the myocarditis group was higher than in the control group (40.0% versus 1.5%, p 0.001). Thirteen (65%) children from the myocarditis group received platelet transfusion compared to 19 (29%) in the control group (p = 0.03).Our study confirms that myocarditis is potentially lethal and identifies higher leukocyte count and platelet transfusion as possible risk factors of myocarditis. A higher resolution version of the Graphical abstract is available as Supplementary information.

The optimal duration of eculizumab treatment in patients with atypical hemolytic uremic syndrome (aHUS) remains poorly defined. We conducted a prospective national multicenter open-label study to assess eculizumab discontinuation in children and adults with aHUS. Fifty-five patients (including 19 children) discontinued eculizumab (mean treatment duration, 16.5 months). Twenty-eight patients (51%) had rare variants in complement genes, mostly in MCP (n = 12; 22%), CFH (n = 6; 11%), and CFI (n = 6; 10%). At eculizumab discontinuation, 17 (30%) and 4 patients (7%) had stage 3 and 4 chronic kidney disease, respectively. During follow-up, 13 patients (23%; 6 children and 7 adults) experienced aHUS relapse. In multivariable analysis, female sex and presence of a rare variant in a complement gene were associated with an increased risk of aHUS relapse, whereas requirement for dialysis during a previous episode of acute aHUS was not. In addition, increased sC5b-9 plasma level at eculizumab discontinuation was associated with a higher risk of aHUS relapse in all patients and in the subset of carriers with a complement gene rare variant, both by log-rank test and in multivariable analysis. Of the 13 relapsing patients, all of whom restarted eculizumab, 11 regained their baseline renal function and 2 had a worsening of their preexisting chronic kidney disease, including 1 patient who progressed to end-stage renal disease. A strategy of eculizumab discontinuation in aHUS patients based on complement genetics is reasonable and safe. It improves the management and quality of life of a sizeable proportion of aHUS patients while reducing the cost of treatment. This trial was registered at www.clinicaltrials.gov as #NCT02574403.

Kidney transplantation (KT) is the optimal treatment for children with end-stage kidney disease. The aim of this study was to evaluate the impact of preemptive kidney transplantation (PKT) and of pretransplant dialysis duration on graft survival among French pediatric kidney transplant recipients.We analyzed all first pediatric kidney-only transplantations performed in France between 1993 and 2012. A Cox multivariable model was used to investigate the association of PKT and pretransplant dialysis time with the hazard of graft failure defined as death, return to dialysis, or retransplant, whichever occurred first.Patients (n = 1911) were included, of which 380 (19.8%) received a PKT. Median time of follow-up was 7.0 y. PKT was associated with a 55% reduction of the hazard of graft failure at any time after KT compared with patients transplanted after dialysis (hazard ratio, 0.45; 95% confidence interval, 0.33-0.62), after adjustment for recipient sex and age, primary kidney disease, donor age and type (living or deceased donor), number of HLA mismatches, cold ischemia time, and year of transplantation. A reduction of the hazard of graft failure was found in PKT whatever the compared duration of dialysis, even when6 mo and whatever the dialysis modality. Results were similar in multiple sensitivity analyses.In France, PKT among pediatric patients is associated with a better graft survival when compared with KT after dialysis, even when6 mo. Based on these findings, we suggest that PKT should be considered as the treatment of choice for children with end-stage kidney disease.

International audience; Background Renal dysfunction can complicate home parenteral nutrition (HPN). The aims were, in the context of pediatric HPN, to assess renal function using the measured glomerular filtration rate (mGFR), determine the most accurate formula(s) to estimate GFR, and identify possible underlying mechanisms of renal impairment.Methods A retrospective study was performed in 2 centers. Patients receiving HPN and aged 2-16 years without medical history of nephropathy were included. GFR was measured using iohexol clearance. Estimated GFR (eGFR) was calculated using creatinine, cystatin C-based, and combined (eGFR(cr+cyst)) Schwartz formulas.Results A total of 36 patients (18 females) were included; they received HPN for 8 (2-16) years. The primary digestive disease was short-bowel syndrome for 16 (44%) patients, gastrointestinal motility disorder for 10 (28%), or congenital diarrhea for 10 (28%). The median (range) mGFR was 99 (33-136) ml/min/1.73 m(2); 9 (25%) patients had mildly decreased mGFR (= 60 ml/min/1.73 m(2)), and 2 (6%) had mildly to severely decreased mGFR (

Background Little data are available for infants who started renal replacement therapy before 6 months of age. Because of extra-renal comorbidities and uncertain outcomes, whether renal replacement therapy in neonates is justified remains debatable. Methods We performed a retrospective analysis of all patients who began chronic peritoneal dialysis below 6 months between 2007 and 2017 in two tertiary centres. Results are presented as median (min;max). Results Seventeen patients (10 boys) were included (8 prenatal diagnoses, 6 premies), with the following diagnoses: congenital anomalies of kidney and urinary tract (n = 9), oxalosis (n = 5), congenital nephrotic syndrome (n = 2) and renal vein thrombosis (n = 1). Five patients had associated comorbidities. At peritoneal dialysis initiation, age was 2.6 (0.1;5.9) months, height-standard deviation score (SDS) −1.3 (−5.7;1.6) and weight-SDS −1.4 (−3.6;0.6). Peritoneal dialysis duration was 12 (2;32) months, and at peritoneal dialysis discontinuation height-SDS was −1.0 (−4.3;0.7) weight-SDS −0.7 (−3.2;0.2), parathyroid hormone 123 (44;1540) ng/L, and hemoglobin 110 (73;174) g/L. During the first 6 months of peritoneal dialysis, the median time of hospitalisation stay was 69 (15;182) days. Ten patients presented a total of 27 peritonitis episodes. Reasons for peritoneal dialysis discontinuation were switch to hemodialysis (n = 6), transplantation (n = 6), recovery of renal function (n = 2) and death (n = 1). After a follow-up of 4.3 (1.7;10.3) years, 12 patients were transplanted, 2 patients were still on peritoneal dialysis, 2 patients were dialysis free with severe chronic kidney disease and 1 patient had died. Seven patients displayed neurodevelopmental delay, of whom five needed special schooling. Conclusion We confirm that most infants starting peritoneal dialysis before 6 months of age will be successfully transplanted and will have a favourable growth outcome. Their quality of life will be impacted by recurrent hospitalisations and neurodevelopmental delay is frequent.

Atypical hemolytic and uremic syndrome (aHUS), a thrombotic micro-angiopathy (TMA) caused by deregulation in the complement pathway, is sometimes due to the presence of anti-complement factor H (CFH) auto-antibodies. The “standard” treatment for such aHUS combines plasma exchange therapy and immunosuppressive drugs. Eculizumab, a monoclonal antibody that blocks the terminal pathway of the complement cascade, could be an interesting alternative in association with an immunosuppressive treatment for maintenance regimen. We report on two children, diagnosed with mildly severe aHUS due to anti-CFH antibodies, who were treated with the association eculizumab–mycophenolate mofetil (MMF). Neither side effects nor relapses were observed during the 3 years of follow-up; MMF was even progressively tapered and withdrawn successfully in one patient. The association of eculizumab and MMF appears to be an effective and safe option in pediatric cases of aHUS due to anti-CFH antibodies of mild severity.

IntroductionGuidelines for the treatment of steroid-dependent nephrotic syndrome (SDNS) and frequently relapsing nephrotic syndrome (FRNS) are lacking. Given the substantial impact of SDNS/FRNS on quality of life, strategies aiming to provide long-term remission while minimising treatment side effects are needed. Several studies confirm that rituximab is effective in preventing early relapses in SDNS/FRNS; however, the long-term relapse rate remains high (~70% at 2 years). This trial will assess the association of intravenous immunoglobulins (IVIgs) to rituximab in patients with SDNS/FRNS and inform clinicians on whether IVIg’s immunomodulatory properties can alter the course of the disease and reduce the use of immunosuppressive drugs and their side effects.Methods and analysisWe conduct an open-label multicentre, randomised, parallel group in a 1:1 ratio, controlled, superiority trial to assess the safety and efficacy of a single infusion of rituximab followed by IVIg compared with rituximab alone in childhood-onset FRNS/SDNS. The primary outcome is the occurrence of first relapse within 24 months. Patients are allocated to receive either rituximab alone (375 mg/m²) or rituximab followed by IVIg, which includes an initial Ig dose of 2 g/kg, followed by 1.5 g/kg injections once a month for the following 5 months (maximum dose: 100 g).Ethics and disseminationThe study has been approved by the ethics committee (Comité de Protection des Personnes) of Ouest I and authorised by the French drug regulatory agency (Agence Nationale de Sécurité du Médicament et des Produits de Santé). Results of the primary study and the secondary aims will be disseminated through peer-reviewed publications.Trial registration numberNCT03560011.

Eplet incompatibility appears to be a better predictor of the de novo appearance of DSA post-Tx than HLA antigen matching in adults. We evaluated the HLA Matchmaker® software (version 2.1) in our pediatric cohort to predict the appearance of DSA post-Tx. We included 70 pediatric patients (26 girls, 10 living donors, mean age 11.2 ± 3.9 years) after a first R-Tx (January 2010-August 2016), without prior immunization, having complete HLA typing (A, B, C, DRB1 and DQB1) and DSA follow-up for at least one year. The mean of HLA and eplet incompatibilities was 4.7 ± 1.3 and 15.5 ± 6.1, respectively, with a correlation coefficient r2 between these two variables of 0.34 (P < .001). The eplet load was 12.8 ± 5.0 in living donors vs 15.9 ± 6.2 in deceased donors (P = NS), 12.6 ± 6.1 in preemptive R-Tx (n = 14) vs 16.3 ± 5.9 for non-preemptive R-Tx (P = .04). Seven patients (10%) developed DSA during the 3.5 ± 1.2 years post-Tx. The eplet load was 13.7 ± 5.5 for those who developed DSA vs 15.7 ± 6.1 for the others (P = NS). In our single-center series of pediatric R-Tx with good HLA matching and lower eplet load than previously published series, eplet incompatibilities do not predict the development of DSA. The question of the HLA matching requirement and the daily interest of the HLA Matchmaker® software to help select the grafts remain open.

International audience; BACKGROUND AND OBJECTIVES: Inherited complement hyperactivation is critical for the pathogenesis of atypical hemolytic uremic syndrome (HUS) but undetermined in postdiarrheal HUS. Our aim was to investigate complement activation and variants of complement genes, and their association with disease severity in children with Shiga toxin-associated HUS.DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Determination of complement biomarkers levels and next-generation sequencing for the six susceptibility genes for atypical HUS were performed in 108 children with a clinical diagnosis of post-diarrheal HUS (75 Shiga toxin-positive, and 33 Shiga toxin-negative) and 80 French controls. As an independent control cohort, we analyzed the genotypes in 503 European individuals from the 1000 Genomes Project.RESULTS: During the acute phase of HUS, plasma levels of C3 and sC5b-9 were increased, and half of patients had decreased membrane cofactor protein expression, which normalized after 2 weeks. Variants with minor allele frequency

Introduction ILLUMINATE-A est un essai de phase 3 du lumasiran, ARNi therapeutique reduisant la production hepatique d’oxalate. Description L’essai a inclus 39 patients ≥ 6 ans atteints d’HP1 avec un DFGe ≥ 30 mL/min/1,73 m2. Methodes L’essai comprenait une periode de 6 mois en double aveugle versus placebo puis une periode d’extension. Resultats A 6 mois, la difference moyenne de traitement par la methode des moindres carres de l’excretion urinaire d’oxalate sur 24 h (UOx) pour le lumasiran vs placebo etait de −53,5 % (p = 1,7 × 10−14) et 84 % des patients sous lumasiran avaient atteint la normalisation ou quasi-normalisation de l’UOx (vs 0 % patients placebo). Dans l’extension, les patients initialement sous placebo ont ete traites par lumasiran demontrant une evolution et ampleur similaires de la reduction d’UOx avec un pourcentage moyen de reduction de 57,3 % et une normalisation ou quasi-normalisation de l’UOx chez 77 % des patients a 6 mois. Chez les patients initialement randomises sous lumasiran, la reduction de l’UOx a ete maintenue a 12 mois. Le taux d’evenements de calculs renaux (ECR) dans le groupe lumasiran a diminue, passant de 0,87 (0,70 ; 1,08) pendant les 12 mois pre-consentement a 0,30 (0,17 ; 0,51) apres 6 mois en double aveugle puis 0,23 (0,13 ; 0,43) apres 6 mois d’extension. Pour les patients initialement sous placebo, le taux d’ECR etait de 0,15 (0,07 ; 0,31) pendant les 12 mois pre-consentement, de 0,18 (0,07 ; 0,48) pendant les 6 mois en double aveugle et de 0,05 (0,01 ; 0,32) pendant les 6 premiers mois sous lumasiran. Comme pour la periode en double aveugle, les evenements indesirables les plus frequents lies au lumasiran dans l’extension etaient des reactions legeres et transitoires au site d’injection. Conclusion La reduction de l’UOx observee dans la periode en double aveugle a ete reproduite par des patients initialement sous placebo confirmant la robustesse du resultat. La baisse des taux d’ECR apres 6 a 12 mois sous lumasiran est encourageante.

In nephrology, some diseases begin specifically during childhood; however, they must be known by adult nephrologists so that to ensure continuity and homogeneity for their management. The aim of this review is therefore to propose a brief overview of the main pediatric diseases, for which a specific knowledge is warranted, and notably pediatric idiopathic nephrotic syndrome, cystinosis, primary hyperoxaluria and hereditaries tubulopathies.

RESUME Les hyperoxaluries primitives sont transmises sur le mode autosomique recessif; il s’agit d’affections rares et souvent graves, engageant alors le pronostic renal et parfois le pronostic vital, notamment dans les formes a debut precoce. Le type 1, le plus frequent, resulte d’un deficit enzymatique (alanine-glyoxylate aminotransferase) dans les peroxysomes du foie, a l’origine d’une hyperoxalurie qui s’exprime initialement par des calculs avec ou sans nephrocalcinose. Au fur et a mesure que la filtration glomerulaire diminue, une surcharge systemique apparait et n’epargne aucun organe, mais l’essentiel du stockage de l’oxalate est osseux. Le diagnostic repose sur l’oxalurie, puis le genotypage, car la confirmation du type d’hyperoxalurie est indispensable a la prise en charge et permet le diagnostic prenatal. Le traitement conservateur (pyridoxine, hydratation, inhibiteurs de la cristallisation) est essentiel et doit etre precoce. Aucune methode de dialyse n’est suffisamment efficace pour compenser la production d’oxalate, de sorte que la transplantation hepatique et renale doit etre planifiee avant le stade d’insuffisance renale avancee, pour limiter les degâts de la thesaurismose. Dans un avenir proche, de nouvelles therapeutiques — notamment ARN interferant — pourront remplacer ou completer la transplantation d’organes. Les hyperoxaluries primitives de type 2 et 3 sont plus rares et ont un phenotype moins severe.

Primary hyperoxalurias are rare disease with autosomal recessive inheritance; they often lead to kidney failure and can lead to life-threatening conditions, especially in early onset forms. There are three types, responding to distinct enzyme deficits. Type 1 represents 85% of cases and results from an enzyme deficiency (alanine-glyoxylate aminotransferase) in the peroxisomes of the liver, causing hyperoxaluria leading to urolithiasis with or without nephrocalcinosis. As glomerular filtration decreases, a systemic overload appears and spares no organ. Treatment has hitherto been based on combined liver and kidney transplantation, with significant mortality and morbidity. The recent introduction of interfering RNA treatments opens up new perspectives. By blocking an enzymatic synthesis (glycolate oxidase or lacticodehydrogenase a) upstream of the deficit that causes the disease, oxaluria normalizes and the tolerance of the drug (administered by injection every 1 to 3 months) is good. This strategy will help prevent kidney failure in patients treated early and avoid liver transplantation in those who are diagnosed at an advanced stage of kidney failure.

Vitamin D deficiency is frequent in pediatric nephrology. The 2017 European guidelines recommend keeping 25OH vitamin D (25-D) levels within the 75-120 nmol/L range, ideally with daily supplementation. Intermittent supplementation with D3 has also been proposed. We aimed to assess the influence of our local protocol of intermittent vitamin D supplementation on the evolution of 25-D levels between baseline and 2 months. VITATOL is a prospective single-center study performed in our tertiary unit in children and teenagers followed for chronic kidney disease (CKD), kidney transplantation, or stable chronic nephrotic syndrome with 25-D levels below 75 nmol/L. Intermittent oral cholecalciferol (100,000 IU) was administered depending on baseline vitamin D levels and body weight. The primary outcome was the change in 25-D levels between baseline and 2 months. Secondary outcomes were the evolution of the main mineral biomarkers. Thirty-seven patients were included. Two months after beginning supplementation, corresponding to a median(min-max) of 46 (14-79) days after the last dose of vitamin D, 25-D levels increased from 50 to 76 nmol/L (p 0.001), 18 patients having 25-D levels within the target range and 2 above. All patients displayed 25-D levels above 50 nmol/L. There were no significant changes in phosphate, PTH, alkaline phosphatase, and FGF23 levels before and after supplementation. Calcium levels increased from 2.39 to 2.44 mmol/L (p = 0.017), but no differences in calciuria and urinary calcium/creatinine ratio were observed.Conclusion: This vitamin D supplementation protocol using intermittent moderate doses of cholecalciferol seems efficient in 54% of cases, with neither significant overdose nor hypercalciuria. What is Known: • Vitamin D deficiency is frequent in pediatric nephrology. • The 2017 European guidelines recommend keeping 25OH vitamin D levels within the 75-120 nmol/L range ideally with daily supplementation, but intermittent supplementation with D3 has also been proposed. What is New: • We assessed the influence of a local protocol of intermittent vitamin D supplementation on the evolution of 25-D levels between baseline and 2 months in children and teenagers followed in pediatric nephrology. • The intermittent cholecalciferol supplementation protocol seems efficient in 54% of cases, with neither significant overdose nor hypercalciuria.

Primary hyperoxaluria type 1 (PH1) is an orphan inborn error of oxalate metabolism leading to hyperoxaluria, progressive renal failure, oxalate deposition, and increased cardiovascular complications. As endothelial dysfunction and arterial stiffness are early markers of cardiovascular risk, we investigated early endothelial and vascular dysfunction in young PH1 patients either under conservative treatment (PH1-Cons) or after combined kidney liver transplantation (PH1-T) in comparison to healthy controls (Cont-H) and patients with a past of renal transplantation (Cont-T). Skin microvascular function was non-invasively assessed by laser Doppler flowmetry before and after stimulation by current, thermal, or pharmacological (nitroprussiate (SNP) or acetylcholine (Ach)) stimuli in young PH1 patients and controls. Seven PH1-Cons (6 F, median age 18.2) and 6 PH1-T (2 F, median age 13.3) were compared to 96 Cont-H (51 F, median age 14.2) and 6 Cont-T (4 F, median age 14.5). The endothelium-independent vasodilatation (SNP) was severely decreased in PH1-T compared to Cont-H. Ach, current-induced vasodilatation (CIV), and thermal response was increased in PH1-Cons and Cont-T compared to controls. PH1-T patients displayed severely decreased smooth muscle capacity to vasodilate. An exacerbated endothelial-dependent vasodilation suggests a role for silent inflammation in the early dysfunction of microcirculation observed in PH1-Cons and Cont-T.

Summary There are limited clinical data regarding prolonged‐release tacrolimus (PR‐T) use in pediatric transplant recipients. This Phase 2 study assessed the efficacy and safety of PR‐T in stable pediatric kidney, liver, and heart transplant recipients (aged ≥5 to ≤16 years) over 1 year following conversion from immediate‐release tacrolimus (IR‐T), on a 1:1 mg total‐daily‐dose basis. Endpoints included the incidence of acute rejection (AR), a composite endpoint of efficacy failure (death, graft loss, biopsy‐confirmed AR, and unknown outcome), and safety. Tacrolimus dose and whole‐blood trough levels (target 3.5–15 ng/ml) were also evaluated. Overall, 79 patients (kidney, n = 48; liver, n = 29; heart, n = 2) were assessed. Following conversion, tacrolimus dose and trough levels remained stable; however, 7.6–17.7% of patients across follow‐up visits had trough levels below the target range. Two (2.5%) patients had AR, and 3 (3.8%) had efficacy failure. No graft loss or deaths were reported. No new safety signals were identified. Drug‐related treatment‐emergent adverse events occurred in 28 patients (35.4%); most were mild, and all resolved. This study suggests that IR‐T to PR‐T conversion is effective and well tolerated over 1 year in pediatric transplant recipients and highlights the importance of therapeutic drug monitoring to maintain target tacrolimus trough levels.

BACKGROUND: Liver lesions of hemolytic uremic syndrome due to Shiga-toxin-producing Escherichia coli (STEC-HUS) are uncommon. CASE-DIAGNOSIS/TREATMENT: We report three observations of severe STEC-HUS with delayed hepatic involvement. They presented with multiple organ failure and received eculizumab; 15 days after the onset of STEC-HUS, cholestasis appeared and cytolysis worsened. Abdominal ultrasonography showed vesicular sludge. Liver biopsy performed 3 to 6 months after the STEC-HUS found cholangiolar proliferation and inflammatory portal fibrosis. Despite renal recovery, cholestasis persisted and worsened in two cases, leading to biliary cirrhosis and subsequent liver transplantation. Pathological examination of one native liver found thrombotic microangiopathy. CONCLUSIONS: Even though the pathological examination performed on one native liver demonstrated areas of thrombotic microangiopathy, we cannot completely rule out that eculizumab may have worsened the liver lesions. Before the efficacy of eculizumab in STEC-HUS is formally demonstrated, physicians should stay cautious in its use.

International audience; Background: Cases reports and small series of patients with C3 glomerulopathy have reported variable efficacy of eculizumab.Study design: Case series of C3 glomerulopathy.Setting & participants: Pediatric and adult patients with C3 glomerulopathy treated with eculizumab between 2010 and 2016 were identified through the C3 glomerulopathy French registry database, and a questionnaire was sent to participating French pediatric and adult nephrology centers, as well as one pediatric referral center in Québec, Canada.Outcomes: Global or partial clinical renal response.Measurements: Evolution of serum creatinine and proteinuria values.Results: 26 patients (13 children/adolescents) were included. 22 (85%) patients had received steroids, plasma exchange, or immunosuppressive therapy before eculizumab, and 3 of them had rapid progression of their kidney disease despite treatment. At the initiation of eculizumab therapy, 11 (42%) patients had chronic kidney disease, 7 (27%) had rapidly progressive disease, and 3 (12%) required dialysis. After eculizumab treatment (median duration, 14 months), 6 (23%) patients had a global clinical response; 6 (23%), a partial clinical response; and 14 (54%), no response. Compared with those who had a partial clinical or no response, patients who had a global clinical response had lower estimated glomerular filtration rates, a more rapidly progressive course, and more extracapillary proliferation on kidney biopsy. Age, extent of renal fibrosis, frequency of nephrotic syndrome, low serum C3 and C3 nephritic factor and elevated soluble C5b-9 concentrations, or complement gene variants did not differ between responders and nonresponders.Limitations: Retrospective design without a control group, relatively small number of cases, inclusion of pediatric and adult cases.Conclusions: Eculizumab appears to be a potential treatment for patients with crescentic rapidly progressive C3 glomerulopathy. Its benefit in patients with non-rapidly progressing forms seems to be limited.

BACKGROUND AND OBJECTIVES: Inherited complement hyperactivation is critical for the pathogenesis of atypical hemolytic uremic syndrome (HUS) but undetermined in postdiarrheal HUS. Our aim was to investigate complement activation and variants of complement genes, and their association with disease severity in children with Shiga toxin–associated HUS. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Determination of complement biomarkers levels and next-generation sequencing for the six susceptibility genes for atypical HUS were performed in 108 children with a clinical diagnosis of post-diarrheal HUS (75 Shiga toxin–positive, and 33 Shiga toxin–negative) and 80 French controls. As an independent control cohort, we analyzed the genotypes in 503 European individuals from the 1000 Genomes Project. RESULTS: During the acute phase of HUS, plasma levels of C3 and sC5b-9 were increased, and half of patients had decreased membrane cofactor protein expression, which normalized after 2 weeks. Variants with minor allele frequency

Background Online hemodiafiltration (oHDF) is increasingly used in children; we treated 28 children since 2009, adapting this technique to pediatric patients. Methods In this service evaluation audit, we assessed plasma electrolytes to evaluate the evolution of total (tCa) and ionized (iCa) during a session, as well as dialysate calcium (dCa) concentrations. Results Using a 1.25 mmol Ca/L-dialysate, both tCa and iCa decreased during the session, with iCa falling below 1.1 mmol/L in 4/5 patients. In contrast, using a 1.5 mmol Ca/L-dialysate, iCa remained normal in all patients. Major discrepancies were observed between the expected and the measured dCa: 1.25 vs. 1.01 (0.83–1.04), and 1.5 vs. 1.47 (0.85–1.75) mmol/L, respectively (results presented as median [range]). These differences were explained by the modality of reconstituting dialysate: increasing bicarbonates and/or decreasing sodium requested in the dialysate decreases calcium extraction from the acid preparation. Proof of concept was given when requesting in an “ex-vivo” setting modifications in the requested sodium and bicarbonate in dialysate directly on the Fresenius machine. Conclusion Nephrologists should be aware that “high bicarbonate and/or low sodium” requirements in oHDF decrease calcium in the dialysate.

Background Thrombotic microangiopathy (TMA) is a severe complication after hematopoietic stem cell transplantation (HSCT), with the reported mortality rate in such cases usually reaching 90%. Cases We report on two pediatric cases of patients successfully treated by eculizumab for severe HSCT-TMA, occurring in two girls (8.4 and 3.6 years). The first patient developed TMA with hematologic abnormalities and renal/pulmonary lesions after allogeneic HSCT for Philadelphia-positive acute lymphoblastic leukemia; she received eculizumab 7 months after HSCT, with a dramatic improvement of renal function. The second patient developed severe TMA (cardiac tamponade, renal failure requiring dialysis, gastritis) after autologous HSCT for metastatic neuroblastoma. She received eculizumab for 7 months, with a dramatic improvement of renal function. No side effects were observed. Conclusion The use of eculizumab as first-line therapy in pediatric patients with severe HSCT-TMA with multisystemic lesions appears promising. Larger international studies are required to confirm its benefit and safety for this specific indication.

BACKGROUND: Hemolytic uremic syndrome related to Shiga-toxin-secreting Escherichia coli infection (STEC-HUS) remains a common cause of acute kidney injury in young children. No specific treatment has been validated for this severe disease. Recently, experimental studies highlight the potential role of complement in STEC-HUS pathophysiology. Eculizumab (EC), a monoclonal antibody against terminal complement complex, has been used in severe STEC-HUS patients, mostly during the 2011 German outbreak, with conflicting results. METHODS: On behalf of the French Society of Pediatric Nephrology, we retrospectively studied 33 children from 15 centers treated with EC for severe STEC-HUS. Indication for EC was neurologic involvement in 20 patients, cardiac and neurologic involvement in 8, cardiac involvement in 2, and digestive involvement in 3. Based on medical status at last follow-up, patients were divided into two groups: favorable (n = 15) and unfavorable outcomes (n = 18). RESULTS: Among patients with favorable outcome, 11/14 patients (79%) displayed persistent blockade of complement activity before each EC reinjection. Conversely, in patients with unfavorable outcome, only 9/15 (53%) had persistent blockade (p = n.s.). Among 28 patients presenting neurological symptoms, 19 had favorable neurological outcome including 17 with prompt recovery following first EC injection. Only two adverse effects potentially related to EC treatment were reported. CONCLUSIONS: Taken together, these results may support EC use in severe STEC-HUS patients, especially those presenting severe neurological symptoms. The study, however, is limited by absence of a control group and use of multiple therapeutic interventions in treatment groups. Thus, prospective, controlled trials should be undertaken.

In nephrology, some diseases begin specifically during childhood; however, they must be known by adult nephrologists so that to ensure continuity and homogeneity for their management. The aim of this review is therefore to propose a brief overview of the main pediatric diseases, for which a specific knowledge is warranted, and notably pediatric idiopathic nephrotic syndrome, cystinosis, primary hyperoxaluria and hereditaries tubulopathies.

Eculizumab may be used to treat C3-glomerulopathy (C3G), a rare but severe glomerular disease. Patients 1, 2 and 3 were diagnosed with nephritic syndrome with alternative complement pathway activation (low C3, C3Nef-positive) and C3G at the age of 9, 13 and 12 years, respectively. Treatment with eculizumab normalized proteinuria within 1, 2 and 7 months, respectively. Proteinuria relapsed when eculizumab was withdrawn, but the re-introduction of eculizumab normalized proteinuria. Patient 4 was diagnosed with C3G at 9 years of age, with progression to end-stage renal disease within 2 years, followed by a first renal transplantation (R-Tx) with early disease recurrence and graft loss within 39 months. After a second R-Tx, she rapidly presented with biological and histological recurrence: therapy with eculizumab was started, with no effect on proteinuria after 5 months, in a complex clinical setting (i.e. association of C3G recurrence, humoral rejection and BK nephritis). Eculizumab was withdrawn due to multiple viral reactivations, but the re-introduction of the drug a few months later enabled a moderate decrease in proteinuria. These cases illustrate the efficacy of eculizumab, at least on native kidneys, in paediatric C3G. However, larger international studies are warranted to confirm the benefit and safety of eculizumab therapy.

Heterozygous mutations of TCF2 (transcription factor 2) have been associated with maturity onset diabetes of the young, renal malformations, hyperuricemia, and occasionally internal genital malformations in female. We report a female patient with bilateral renal hypodysplasia and de novo heterozygous TCF2 gene mutation. At the age of 9 yr, she developed transient ketoacidosis immediately posttransplant, temporarily requiring insulin. During glucocorticoid tapering, impaired glucose tolerance persisted and overt insulin-dependent diabetes mellitus developed 1 yr later. Pathogenic factors which might have played a role in the acceleration of diabetes were (i) switch from cyclosporine to tacrolimus, (ii) weight excess, and (iii) cytomegalovirus infection. TCF2 analysis might, therefore, be of interest in patients with congenital abnormalities of the kidney and the urinary tract in order to improve posttransplant management in terms of steroid and tacrolimus exposure.

Plasmatherapy has become empirically first-line treatment in atypical hemolytic uremic syndrome (aHUS), although no prospective controlled trials have been conducted. Patients with mutations that induce complete or partial factor H (FH) quantitative deficiency may be controlled by plasma infusions (PI), but plasma exchanges appear more efficient than PI in patients with mutations that result in a mutant dysfunctional FH in the circulation. Early treatment is crucial. Long-term prophylactic plasmatherapy appears more efficient to prevent end-stage renal disease (ESRD) than plasmatherapy only during relapses. However, the longest follow-up with preserved renal function under plasmatherapy is only 6.5 years. Plasmatherapy does not appear to influence the outcome of aHUS with membrane cofactor protein mutation, and its efficacy in patients with factor I, C3, or factor B mutations is suggested by a few reports. We hope complement blockers will offer patients a better chance to avoid ESRD and provide a better quality of life.

The etiology of idiopathic nephrotic syndrome (INS) remains partially unknown. Viral infections have been reported to be associated with INS onset and relapse. The aim of this study was to describe the epidemiology of a population-based cohort of children with INS and propose a spatiotemporal analysis. All children aged 6 months to 15 years with INS onset between December 2007 and May 2010 and living in the Paris area were included in a prospective multicenter study. Demographic and clinical features at diagnosis and 2 years were collected. INS was diagnosed in 188 children, 93 % of whom were steroid sensitive. Annual incidence was 3.35/100,000 children. Standardized incidence ratio (SIR) was higher in one of the eight counties: Seine-Saint-Denis, with SIR 1.43 [95 % confidence interval (CI) 1.02–1.95]. A spatial cluster was further identified with higher SIR 1.36 (95 % CI 1.09–1.67). Temporal analysis within this overincidence area showed seasonal variation, with a peak during the winter period (p

International audience; Dent disease is a rare X-linked tubulopathy characterized by low molecular weight proteinuria, hypercalciuria, nephrocalcinosis and/or nephrolithiasis, progressive renal failure, and variable manifestations of other proximal tubule dysfunctions. It often progresses over a few decades to chronic renal insufficiency, and therefore molecular characterization is important to allow appropriate genetic counseling. Two genetic subtypes have been described to date: Dent disease 1 is caused by mutations of the CLCN5 gene, coding for the chloride/proton exchanger ClC-5; and Dent disease 2 by mutations of the OCRL gene, coding for the inositol polyphosphate 5-phosphatase OCRL-1. Herein, we review previously reported mutations (n = 192) and their associated phenotype in 377 male patients with Dent disease 1 and describe phenotype and novel (n = 42) and recurrent mutations (n = 24) in a large cohort of 117 Dent disease 1 patients belonging to 90 families. The novel missense and in-frame mutations described were mapped onto a three-dimensional homology model of the ClC-5 protein. This analysis suggests that these mutations affect the dimerization process, helix stability, or transport. The phenotype of our cohort patients supports and extends the phenotype that has been reported in smaller studies.

Introduction Post-transplant infection-related hospitalisations have increased over time in children after renal transplantation. We attempt to describe those hospitalisations in a cohort of paediatric renal transplant recipients, to study the risk factors of infections and to evaluate the additional cost of those hospitalisations. Material and methods Patients under 20 years receiving a kidney transplant in France between 2008 and 2013 were screened from the National medico-administrative Hospital Discharge database and a probabilistic matching was performed with the National Renal Transplant Database. Costs’ calculation was based on the Public Health Care Tariff. We used Cox regression to study the risk factors of hospitalisation. To assess the evolution of the risk with time, we calculated the instantaneous risk of hospitalisation per month for all infections and by type of infection. Results Among 593 patients, 660 hospitalisations in 260 patients were identified; median follow-up time was 34.7 [14.7–53.2] months. The first cause of hospitalisation was UTI, incidence rate of 16.6 per 100 patient–years (py) followed by viral infections (15.6/100 py) including 128 digestive infections, 70 respiratory tract infections and 47 hospitalizations related to herpes viruses. Risk factors of hospitalisation were a younger age [HR 0.95 (0.92–0.97) per year], HLA mismatches [HR 1.14 (1.01–1.28) per mismatch] and the use of Cyclosporine rather than tacrolimus [HR 0.72 (0.54–0.95)]. Female gender, uropathy and cold ischemia time were specific risk factors of UTI. Instantaneous risk of infection decreased with time but CMV infection displayed a peak at the end of the prophylaxis. Total cost of infection-related hospitalisations was 1600k € (933 €/py) for 3529 days of hospitalisation. Conclusion This study points out the high burden of infection in paediatric transplanted patients, especially the youngest ones in terms of quality of life and health cost and highlights possible ways of improvement for clinical practice.