Cell-Free DNA for the detection of kidney allograft rejection.

Donor-derived cell-free DNA (dd-cfDNA) is an emerging non-invasive biomarker that has the potential to detect allograft injury. The capacity of donor-derived cell-free DNA to detect kidney allograft rejection and its added clinical value beyond standard of care patient monitoring is unclear. We enrolled 2,882 kidney allograft recipients from 14 transplantation centers in Europe and the US in an observational population-based study. The primary analysis included 1,134 patients. Donor-derived cell-free DNA levels strongly correlated with allograft rejection including antibody-mediated rejection (p < 0.0001), T-Cell mediated rejection (p < 0.0001) and mixed rejection (p < 0.0001). In multivariable analysis, circulating dd-cfDNA was significantly associated with allograft rejection (OR: 2.275; CI:1.902-2.739; p < 0.0001) independently of standard of care patient monitoring parameters. The inclusion of dd-cfDNA to a standard of care prediction model showed improved discrimination (0.777 [95% CI: 0.741-0.811] to 0.821 [95% CI: 0.784-0.852]; p = 0.0011) and calibration. These results were confirmed in the external validation cohorts (n = 1,748) including a cohort of African American patients (n = 439). Finally, dd-cfDNA showed high predictive value to detect subclinical rejection in stable patients. Our study provides insights on the potential value of assessing dd-cfDNA, in addition to standard of care monitoring, to improve the detection of allograft rejection. ClinicalTrials.gov registration: NCT05995379.

Beyond traditional venous access: Midline catheter use in pediatric apheresis.

The objective of this study was to assess the use of midline catheters as venous access for apheresis procedures in pediatric patients. A retrospective analysis of medical records was conducted from September 2019 to June 2022 to evaluate the safety and efficacy of midline catheters for therapeutic pediatric apheresis. During the study period, a total of 121 procedures were inserted in 22 unique patients. The age of the subjects ranged from 2.7 to 21 years. The blood flow rates achieved with midline catheters met or exceeded the recommended rates for apheresis in children (40 mL/min), by the Wilcoxon signed-rank test (p < 0.0001). There was one episode of catheter-related thrombosis, but no cases of bloodstream infection or catheter dislodgement were reported. In conclusion, this study supports the use of midline catheters as a safe and effective alternative for venous access during therapeutic and donor apheresis procedures in pediatric patients.

Physician knowledge, attitudes, and practices regarding physical activity restrictions in pediatric hemodialysis patients.

INTRODUCTION: Epidemiologic studies of physical activity among pediatric hemodialysis (HD) patients are lacking. A sedentary lifestyle in End-Stage Kidney Disease is associated with a higher cardiovascular mortality risk. In those patients receiving HD, time spent on dialysis and restrictions on physical activity due to access also contribute. No consensus exists regarding physical activity restrictions based on vascular access type. The aim of this study was to describe the patterns of physical activity restrictions imposed by pediatric nephrologists on pediatric HD patients and to understand the basis for these restrictions. METHODS: We conducted a cross-sectional study involving US pediatric nephrologists using an anonymized survey through Pediatric Nephrology Research Consortium. The survey consisted of 19 items, 6 questions detailed physician characteristics with the subsequent 13 addressing physical activity restrictions. FINDINGS: A total of 35 responses (35% response rate) were received. The average years in practice after fellowship was 11.5 years. Significant restrictions were placed on physical activity and water exposure. None of the participants reported accesses damage or loss that was attributed to physical activity and sport participation. Physicians practice is based on their personal experience, standard practice at their HD center, and clinical practices they were taught. DISCUSSION: There is no consensus among pediatric nephrologists about allowable physical activity in children receiving HD. Due to the lack of objective data, individual physician beliefs have been utilized to restrict activities in the absence of any deleterious effects to accesses. This survey clearly demonstrates the need for more prospective and detailed studies to develop guidelines regarding physical activity and dialysis access in order to optimize quality of care in these children.

Longitudinal Evaluation of Donor-Derived Cellfree DNA in Pediatric Kidney Transplantation.

BACKGROUND AND OBJECTIVES: Donor-derived cellfree DNA (cfDNA) is a less-invasive marker of allograft injury compared with kidney biopsy. However, donor-derived cfDNA has not yet been extensively tested in children, where the test may have different characteristics. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We assayed donor-derived cfDNA (AlloSure; CareDx) from 290 stored plasma samples from a prospective biobank at our center, collected from 57 children monthly in the first year postkidney transplant between January 2013 and December 2019. We assessed the kinetic changes in donor-derived cfDNA levels within the first year post-transplant. We analyzed donor-derived cfDNA levels for associations with biopsy-proven acute rejection using area under the receiver operating characteristic curve to longitudinal plasma and urine BK viral loads using linear mixed models. We analyzed the prognostic effect of an elevated donor-derived cfDNA level on the eGFR 30 days after the assay via Kolmogorov-Smirnov two-sample tests or on measured GFR or interstitial fibrosis at 12 months post-transplant. RESULTS: The donor-derived cfDNA levels in children remained persistently elevated for at least 4 months post-transplant, more so if there is greater disparity in size between the donor and the recipient, before reaching a steady low level. A donor-derived cfDNA level of >1% discriminated between biopsy-proven acute rejection with a receiver operating characteristic area under the curve of 0.82 (95% confidence interval, 0.71 to 0.93). During BK viruria or viremia, patients had a significantly higher median donor-derived cfDNA than before or after and a significant rise within the same patient. A donor-derived cfDNA of >0.5% predicted a wider spread in the eGFR over the next 30 days but not the 12-month outcomes. CONCLUSIONS: In children, donor-derived cfDNA is a valuable, less invasive biomarker for assessment of allograft rejection and injury. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_10_27_CJN03840322.mp3.

Donor-derived Ehrlichiosis: 2 Clusters Following Solid Organ Transplantation.

Ehrlichiosis has been infrequently described as transmissible through organ transplantation. Two donor-derived clusters of ehrlichiosis are described here. During the summer of 2020, 2 cases of ehrlichiosis were reported to the Organ Procurement and Transplantation Network (OPTN) and the Centers for Disease Control and Prevention (CDC) for investigation. Additional transplant centers were contacted to investigate similar illness in other recipients and samples were sent to the CDC. Two kidney recipients from a common donor developed fatal ehrlichiosis-induced hemophagocytic lymphocytic histiocytosis. Two kidney recipients and a liver recipient from another common donor developed ehrlichiosis. All 3 were successfully treated. Clinicians should consider donor-derived ehrlichiosis when evaluating recipients with fever early after transplantation after more common causes are ruled out, especially if the donor has epidemiological risk factors for infection. Suspected cases should be reported to the organ procurement organization and the OPTN for further investigation by public health authorities.

Performance of the various serum creatinine-based GFR estimating equations in pediatric kidney transplant recipients, stratified by age and CKD staging.

BACKGROUND: Numerous equations are used to estimate glomerular filtration rate (eGFR), based on serum creatinine (SCr), demographic and anthropometric data, none established in pediatric kidney transplant recipients. This study aimed to validate the available SCr-based eGFR equations in comparison with a measured (mGFR), stratified by chronic kidney disease (CKD) stage and age at the time of testing. METHODS: One hundred twenty-seven pediatric kidney transplant recipients with 411 mGFR values (plasma clearance of iothalamate) were enrolled in this retrospective study. The bias, precision, and accuracy (percentage of estimates within 10% and 30% of mGFR) of five SCr eGFR equations (original Schwartz, CKiDSCr equation, Pottel, Modification of Diet in Renal Disease (MDRD), and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)) were assessed. RESULTS: Height-independent Pottel equation performed well across all the categories of age and CKD staging. CKiDSCr equation performed well in CKD stages II-V. The CKiDSCr equation had a lower bias in children < 15 years of age, while MDRD and CKD-EPI equations had less bias in children > 15 years. Overall, both the Pottel and CKiDSCr equations had high accuracy (80%) and low bias (< 5 ml/min/1.73 m2). In contrast, the original Schwartz, MDRD, and CKD-EPI equations displayed high bias and low precision/accuracy. CONCLUSIONS: Given their low bias and high accuracy across ages and CKD stages, the Pottel or the CKiDSCr equation is better to assess eGFR in pediatric kidney transplant recipients. The Pottel equation outperformed other eGFR equations in adolescents.

Rare cause of xanthinuria: a pediatric case of molybdenum cofactor deficiency B.

Molybdenum cofactor is essential for the activity of multiple enzymes including xanthine dehydrogenase. Molybdenum cofactor deficiencies are rare inborn errors of metabolism. Clinically, they present with intractable seizures, axial hypotonia, and hyperekplexia. They further develop cerebral atrophy, microcephaly, global developmental delay and ectopia lentis. We report a 5-year-old female with clinically, biochemically and genetically confirmed molybdenum cofactor deficiency type B due to compound heterozygous pathogenic variants in the molybdenum cofactor synthesis 2 gene found on whole exome sequencing. The xanthine stones were a key clue towards diagnosis. No mutation was detected in XDH gene. Implementation of a low-purine diet, urine alkalization and hydration lead to a near complete decrease in stone burden. The patient received pyridoxine supplementation with improvement in energy levels and attentiveness. Despite reports of high mortality at a young age, our patient was 9 years old at the time of this writing. Molybdenum cofactor deficiencies should be considered in neonates with early-onset seizures, hypotonia, and feeding difficulties. Screening with serum uric acid levels and empiric treatment may be considered while awaiting genetic results.

Late first acute rejection in pediatric kidney transplantation: A North American Pediatric Renal Trials and Collaborative Studies special study.

Rates of early AR in pediatric kidney transplantation have declined in every era but the most recent NAPRTCS cohort has shown an increase in late first AR rates. We hypothesized this was due to an increased proportion of deceased donor utilization and early steroid taper utilization. Using the NAPRTCS database, we compared the most recent three cohorts of patients transplanted between 2002-2006, 2007-2011, and 2012-2017. To determine variables that predict late first AR, we used two multivariable models: a standard Cox regression model and LASSO model. From the LASSO model, deceased donor source (P = .002), higher recipient age (P = .019), black race (P = .010), and transplant cohort 2012-17 (P = .014) were all significant predictors of more late first AR. On standard Cox regression analysis, those same variables, minus donor source, were significant, in addition to mycophenolates usage (P = .007) and lower eGFR at 12 months (P = .02). The most recent 2012-2017 cohort remains an independently significant risk factor for late first AR, suggesting unmeasured variables. Further research is needed to determine whether these higher late first AR rates will impact long-term graft survival in the most recent cohort.

Thrombotic Microangiopathy Following Onasemnogene Abeparvovec for Spinal Muscular Atrophy: A Case Series.

Spinal muscular atrophy is treated with onasemnogene abeparvovec, which replaces the missing survival motor neuron 1 gene via an adeno-associated virus vector. As of July 1, 2020, we had identified 3 infants who developed thrombotic microangiopathy following onasemnogene abeparvovec. Early recognition and treatment of drug-induced thrombotic microangiopathy may lessen mortality and morbidity.

Renal transplantation and predisposition to opportunistic infections.

PURPOSE OF REVIEW: Infections represent a significant source of morbidity and mortality after kidney transplantation in children. We review recent advances in epidemiology, assessment, prevention and treatment for several different infections. RECENT FINDINGS: Infections, such as bacterial urinary tract infection or opportunistic viral infection remain common, may be increasing and represent a large proportion of hospitalization. Extended antiviral agent use reduces the incidence of cytomegalovirus disease but its efficacy to reduce Epstein-Barr virus disease remains controversial. Human herpesvirus-6 and hepatitis E virus represent new infections to keep in mind. Ureteral stenting increases the rate of early UTI. Several new vaccines are now available, but rates of complete vaccination pretransplant are low. SUMMARY: Infections remain a critical posttransplant issue associated with significant medical burdens. Emerging data on associated risk factors, assessment of and treatment for infections provide clinicians with new knowledge.