IPNA clinical practice recommendations for the diagnosis and management of children with steroid-resistant nephrotic syndrome

Factors associated with chronic calcineurin inhibitor nephrotoxicity in children with minimal-change disease

BACKGROUND

Calcineurin inhibitors (CNIs), such as cyclosporine (CsA) and tacrolimus (TAC), are commonly used to treat children with complicated minimal change nephrotic syndrome. However, chronic nephrotoxicity associated with CNIs poses a significant safety concern. This study aimed to identify the risk factors that contribute to chronic nephrotoxicity in these patients.

MATERIAL AND METHODS

Clinical and pathological data of MCD children treated with CsA or TAC in our center between 1 January 2003 and 31 December 2022, were retrospectively reviewed. Kidney biopsies were performed on 80 patients who received CNI treatment for more than 6 months.

RESULTS

Chronic CNI nephrotoxicity (striped interstitial fibrosis with tubular atrophy) was observed in 15% (12/80) of patients. Higher CNI culminating amounts were shown in patients who developed nephrotoxicity regardless of CsA or TAC treatment. Risk factors for chronic CNI nephrotoxicity included persistent nephrotic-range proteinuria for more than 30 days during CNI treatment, increased urinary NAG level, and CNI resistance. Multivariate analysis revealed that increased urinary NAG level and CNI resistance were the independent risk factors for chronic CNI nephrotoxicity in children with MCD.

CONCLUSION

MCD children who developed CNI resistance were susceptible to chronic CNI nephrotoxicity. Urinary NAG might be a valuable biomarker for CNI nephrotoxicity prediction in MCD children.

Outcomes and prognostic factors in childhood-onset steroid-resistant nephrotic syndrome: a retrospective single-center study

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is the second leading cause of chronic kidney disease (CKD) in childhood. It represents a heterogeneous group of diseases with variable kidney outcomes that are still challenging to predict. In this study, our main objective is to describe predictive factors of remission states and kidney survival comparing genetic and non-genetic SRNS.

METHODS

We conducted a retrospective analysis of 65 pediatric patients with SRNS treated at the pediatric outpatient clinic in Berlin between 2000 and 2023. Clinical characteristics, laboratory findings, and treatment strategies were systematically collected at multiple time points. Outcomes were defined by remission status, kidney survival (CKD stage I-IV), or progression to CKD stage V. Statistical analyses included univariate and multivariate logistic and Cox regression models adjusted for monogenic SRNS to identify predictors of remission and kidney survival.

RESULTS

The median age of onset was 4.0 years, with a male predominance of 57%. Patients were followed for a median of 5.9 years. At the last follow-up, 26 patients achieved complete remission, 12 achieved partial remission, and 27 showed no remission. Kidney survival rates at 5 and 10 years were 71% and 56%, respectively. High initial nephrotic-range proteinuria, confirmed genetic diagnoses, reduced eGFR, and hypoalbuminemia at 3-month and 1-year follow-ups were identified as negative predictive factors for complete or partial remission. These factors also correlated strongly with an elevated risk of progression to CKD stage V.

CONCLUSION

Our findings highlight additional prognostic factors influencing remission status and long-term kidney survival in pediatric SRNS, emphasizing the value of detailed early time-point analyses.

The application of omalizumab in children with atopic diseases complicated by nephrotic syndrome: a case report

Nephrotic syndrome (NS) and atopic diseases are linked through shared immunological pathways, with allergic triggers often contributing to NS relapses, particularly in immunoglobulin E (IgE)-mediated pathways. Omalizumab, a humanized monoclonal antibody targeting free and cell-bound IgE, is commonly used in treating atopic diseases. We presented a pediatric case with a history of eczema, asthma, and recurrent atopic rhinitis, who first developed NS at age three, responding well to steroid therapy. The patient experienced four NS relapses, three of which were associated with significant atopic symptoms, elevated eosinophil counts, and increased IgE levels, suggesting allergic triggers. After the latest relapse achieved remission, steroid therapy was discontinued, and Omalizumab was initiated two months later. The patient received monthly subcutaneous Omalizumab (300 mg) with regular urine protein monitoring. To date, the patient has shown marked improvement in atopic symptoms, sustained NS control, and reduced steroid dependence. This case highlights the potential of Omalizumab in treating NS triggered by allergic reactions, further prospective pilot studies and randomized controlled trials are warranted to rigorously evaluate its efficacy and safety.

Whole genome sequencing identifies monogenic disease in 56.1% of families with early-onset steroid-resistant nephrotic syndrome

Genetic causes of steroid-resistant-nephrotic-syndrome (SRNS) represent a rapidly growing number of monogenic diseases. The reported diagnostic yield of various studies applying genetic panels and exome-sequencing to diagnose SRNS is usually < 30%. We performed genome-sequencing in a cohort of Egyptian SRNS patients. We recruited 47 SRNS patients belonging to 41 unrelated families [28 males/19 females; median (range): 6 (0.5-22 years)]. We established a pipeline for genome sequencing, bioinformatics analysis, variant curation and protein modeling at the Egypt Center for Research and Regenerative Medicine (ECRRM). Disease-causing variants were detected in 27/47 patients (57.4%) belonging to 23/41 families (56.1%), including nine novel variants in NPHS1, NPHS2, COL4A3, MYO1E, NUP93, PLCE1, PODXL, SMARCAL1 and WT1. Novel variants were confirmed by Sanger sequencing and were segregated in families of affected patients. NPHS2 was the most common causative gene in 8/23 (34.8%) of confirmed families, followed by NPHS1, WT1, and SMARCAL1 in 2/23 families (8.7%) each. All detected missense variants were evaluated through protein modeling and were predicted deleterious. Our study expanded the spectrum of SRNS disease-causing variants and revealed a monogenic cause in 56.1% of investigated families. In our cohort, no deep intronic or regulatory variants were detected by genome-sequencing. Pursuing genetic diagnosis in SRNS patients is crucial to inform clinical decision making, genetic counseling, transplantation strategy and prenatal diagnosis thus improving clinical outcome of affected patients.

Anti-nephrin antibodies guide living donor kidney transplantation in a pediatric patient with primary focal segmental glomerular sclerosis

INTRODUCTION

Disease recurrence after kidney transplantation (KTx) remains a major challenge in patients with primary focal segmental glomerulosclerosis (pFSGS). Antibodies targeting the slit diaphragm protein nephrin have been identified in patients with early disease recurrence. Here, we describe monitoring and effective pre-transplant elimination of anti-nephrin antibodies in an adolescent with pFSGS prior to living-donor KTx.

METHODS

Anti-nephrin antibodies were assessed in pre- and post-transplant serum samples by ELISA, Western blot and immunoprecipitation using three different nephrin proteins.

RESULTS

Pre-transplant treatment including rituximab and repetitive therapeutic plasma exchanges resulted in effective and sustainable reduction of anti-nephrin antibodies. Allograft function has remained excellent without albuminuria over a follow-up of more than one year. Further analysis showed, that the antibodies were cross-reactive with NEPH3 (filtrin), another key slit diaphragm protein.

CONCLUSIONS

Monitoring and pre-transplant elimination of anti-slit diaphragm antibodies may become a standard, personalized approach in patients with pFSGS requiring KTx.

SIRT1: potential target in glucocorticoid-resistant diseases

Glucocorticoid resistance is a challenging problem in clinical practice. Increasing glucocorticoid sensitivity and reducing resistance are important in the management of certain diseases. In steroid-resistant airway inflammatory diseases, glucocorticoid receptor (GR) expression is reduced, and impaired GR nuclear translocation is closely related to glucocorticoid resistance. Histone deacetylase SIRT1 regulates steroid hormone receptor activity and interacts with the androgen receptor and GR. In some glucocorticoid-resistant diseases, SIRT1 expression is reduced. Here, we review recent advances in the role of SIRT1 in regulating glucocorticoid signaling. First, we describe the structure, tissue expression, and subcellular localization of SIRT1. We also discuss the molecular mechanisms by which SIRT1 regulates glucocorticoid activity and its association with GR, as well as the mechanisms and roles of SIRT1 in several common glucocorticoid-resistant diseases. SIRT1 may serve as a potential therapeutic target, providing an opportunity for the treatment of glucocorticoid-resistant diseases.

Interventions for idiopathic steroid-resistant nephrotic syndrome in children

BACKGROUND

Nephrotic syndrome is a condition in which the glomeruli of the kidney leak large amounts of protein from the blood into the urine. Most children who present with their first episode of nephrotic syndrome achieve remission with corticosteroids. Children who fail to respond to corticosteroids in the first episode of nephrotic syndrome (initial resistance) or develop resistance after one or more responses to corticosteroids (delayed resistance) may be treated with immunosuppressive agents, including calcineurin inhibitors (cyclosporin or tacrolimus), and with non-immunosuppressive agents, such as angiotensin-converting enzyme inhibitors and angiotensin receptor blockers. However, response to these agents is limited, so newer agents, including anti-CD20 antibodies (rituximab, ofatumumab) and dual endothelin-angiotensin receptor antagonists (sparsentan), are being assessed for efficacy and safety. This is an update of a review first published in 2004 and updated in 2006, 2010, 2016 and 2019.

OBJECTIVES

To evaluate the benefits and harms of different interventions used in children with idiopathic nephrotic syndrome, who do not achieve remission following four weeks or more of daily corticosteroid therapy.

SEARCH METHODS

The Cochrane Kidney and Transplant (CKT) Information Specialist searched the CKT Register of Studies to 28 January 2025 using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE and Embase, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) and quasi-RCTs that compared different immunosuppressive or non-immunosuppressive agents with placebo, prednisone or another agent given orally or parenterally in children aged three months to 18 years with steroid-resistant nephrotic syndrome (SRNS). We included studies that enrolled children and adults, in which paediatric data could not be separated from adult data.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results, determined study eligibility, assessed risk of bias and extracted study data. We expressed dichotomous outcomes as risk ratios (RRs) with 95% confidence intervals (CIs), and continuous outcomes as mean differences (MDs) with 95% CIs. We used a random-effects model to pool data, and GRADE to assess the certainty of the evidence. The main outcomes of interest were treatment response (complete, partial, or complete or partial remission), kidney failure and adverse events.

MAIN RESULTS

We included 29 studies (1248 evaluated children). Sixteen studies were at low risk of bias for sequence generation and allocation concealment. Seven and 21 studies were at low risk of performance and detection bias, respectively. Sixteen, 15 and 15 studies were at low risk of attrition bias, reporting bias and other bias, respectively. Compared with placebo, corticosteroid or no treatment, cyclosporin may increase the number who achieve complete remission (RR 3.50, 95% CI 1.09 to 11.20; 4 studies, 74 children) or complete or partial remission (RR 3.15, 95% CI 1.04 to 9.57; 4 studies, 74 children) by two to six months (low-certainty evidence). It is uncertain whether cyclosporin reduces the likelihood of kidney failure or increases the likelihood of worsening hypertension or infection (very low-certainty evidence). Compared with intravenous cyclophosphamide, calcineurin inhibitors may increase the number with complete remission (RR 3.43, 95% CI 1.84 to 6.41; 2 studies, 156 children) and complete or partial remission (RR 1.98, 95% CI 1.25 to 3.13; 2 studies, 156 children) at three to six months (low-certainty evidence), and probably reduces the number with treatment failure (no response, serious infection, persistently elevated creatinine) and medications ceased due to adverse events (moderate-certainty evidence), with little or no increase in serious infections (moderate-certainty evidence). Kidney failure was not reported. Tacrolimus may make little or no difference to the number who achieve complete, or complete or partial remission at six and 12 months compared with cyclosporin, but may reduce the number who relapse during treatment (RR 0.22, 95% CI 0.06 to 0.90; 1 study, 34 children) or the number with worsening hypertension (low-certainty evidence). Hypertrichosis and gingival hyperplasia probably increased with cyclosporin. Kidney failure was not reported. Compared with mycophenolate mofetil (MMF) and dexamethasone, cyclosporin probably makes little or no difference to complete, partial, or complete or partial remission (moderate-certainty evidence), and may make little or no difference to kidney failure, serious infection requiring hospitalisation or hypertension (low-certainty evidence). Among children who have achieved complete remission, tacrolimus compared with MMF may increase the number who maintain complete, partial, or complete or partial response for 12 months, but may make little or no difference to serious adverse events and serious infection (low-certainty evidence). Oral cyclophosphamide plus prednisone compared with prednisone alone may make little or no difference to the number who achieve complete remission (low-certainty evidence) and has uncertain effects on adverse events. Kidney failure was not reported. Compared with oral cyclophosphamide plus intravenous dexamethasone, intravenous cyclophosphamide may make little or no difference to complete, partial, or complete or partial remission at six months. There may be little or no difference in bacterial infections; however, hypertension may decrease (all low-certainty evidence). Kidney failure was not reported. It is uncertain whether rituximab/cyclosporin/prednisolone compared with cyclosporin/prednisolone increases the likelihood of remission or reduces adverse events because the certainty of the evidence is very low. Kidney failure was not reported.

AUTHORS' CONCLUSIONS

Calcineurin inhibitors may increase the likelihood of complete or partial remission compared with placebo/no treatment or cyclophosphamide. For other regimens, it remains unclear whether the interventions alter outcomes because the certainty of the evidence is low. Further adequately powered, well-designed RCTs are needed to evaluate other regimens for children with idiopathic SRNS. Since SRNS represents a spectrum of diseases, future studies should enrol children from better-defined groups of people with SRNS.

Mechanisms of podocyte injury in genetic kidney disease

Glomerular diseases are a leading cause of chronic kidney disease worldwide. Both acquired and hereditary glomerulopathies frequently share a common final disease mechanism: disruption of the glomerular filtration barrier, podocyte injury, and ultimately podocyte death and detachment. Over 70 monogenic causes of proteinuric kidney disease have been identified, and most of these genes are highly expressed in podocytes, regulating key processes such as maintenance of the slit diaphragm, regulation of actin cytoskeleton remodeling, and modulation of downstream transcriptional pathways. Collectively, these are increasingly being referred to as hereditary "podocytopathies," in which podocyte injury is the central feature driving proteinuria and kidney dysfunction. In this review, we provide an overview of the monogenic podocytopathies and discuss the molecular mechanisms by which single-gene defects lead to podocyte injury and ultimately glomerulosclerosis. We review how advances in genomic technology and a better understanding of the cell biological basis of disease have led to the development of more targeted and personalized therapeutic strategies, including an overview of small molecule and gene therapy approaches.

Executive summary of the KDIGO 2025 Clinical Practice Guideline for the Management of Nephrotic Syndrome in Children

The Kidney Disease: Improving Global Outcomes (KDIGO) Clinical Practice Guideline for the Management of Glomerular Diseases was last updated and published in 2021. KDIGO continues to be committed to the nephrology community to provide periodic updates, based on new developments for each of the glomerular diseases. For children with nephrotic syndrome, the updated guideline now contains a treatment algorithm on when to perform a kidney biopsy and/or genetic testing and which immunosuppressive therapy to use in children with a complete response to glucocorticoids (steroid sensitive), who subsequently become infrequent or frequent relapsers or even steroid dependent. If a glucocorticoid-sparing agent must be considered after failure of an initial glucocorticoid therapy to induce remission, the choice among a calcineurin inhibitor, oral cyclophosphamide, levamisole, mycophenolate mofetil, and rituximab is a decision that requires consideration of patient-related issues such as resources, adherence, adverse effects, and patient preferences. Herein, an executive summary of the most important changes in the KDIGO 2025 Clinical Practice Guideline for the Management of Nephrotic Syndrome in Children is provided as a quick reference.

Emerging pharmacotherapies for the treatment of childhood nephrotic syndrome

INTRODUCTION

Childhood nephrotic syndrome (NS) is a relatively rare condition but an important cause of morbidity. It is classified based on histopathology and response to corticosteroid therapy.

AREAS COVERED

Children with steroid-sensitive disease have a favorable long-term prognosis with maintenance of normal kidney function. However, nearly half of these patients have persistent disease activity requiring chronic corticosteroid therapy or exposure to second-line immunosuppressive agents. The identification of anti-nephrin antibodies in many patients with steroid-sensitive disease suggests immunotherapy to reduce pathogenic antibody formation may represent a qualitative advance in treatment. Children with steroid-resistant disease are likely to have focal segmental glomerulosclerosis (FSGS). There are no approved treatments for this condition. FSGS is a heterogeneous entity, and improvements in care will likely depend on molecular classification of subtypes based on the underlying disease mechanism. This approach will enable selection of treatments that match the cause of NS in each child for precision medicine therapy.

EXPERT OPINION

Children with NS today benefit from therapeutic options not previously available, but clinical decisions still rely on steroid responsiveness at disease onset. Continued advancement in treating NS requires collaboration between basic scientists and nephrologists and the organization of a clinical trial framework to evaluate novel therapies.

Genetic and clinical spectrum of steroid-resistant nephrotic syndrome with nuclear pore gene mutation

BACKGROUND

Steroid-resistant nephrotic syndrome (SRNS) is insensitive to steroid therapy and overwhelmingly progresses to kidney failure (KF), the known pathogenic genes of which include key subunits of the nuclear pore complex (NPC), a less-recognized contributor to glomerular podocyte injury.

METHODS

After analyzing their clinical characterizations and obtaining parental consent, whole-exome sequencing (WES) was performed on patients with SRNS. Several nucleoporin (NUP) biallelic pathogenic variants were identified and further analyzed by cDNA-PCR sequencing from white cells of peripheral blood, minigene assay, immunohistochemical (IHC) staining, and electron microscopy (EM) ultrastructure observation of kidney biopsy, as well as multiple in silico prediction tools, including 3D protein modeling.

RESULTS

Here, in six families with SRNS, we identified pathogenic mutations in NUP85/93/107/160 genes. Specifically, the patient with NUP93 mutation developed KF six months after diagnosis at 1 year 2 months. Two missense mutations, c.1655A > G and c.1604A > C, disrupted the protein stability of NUP93 by IHC staining of kidney biopsy. Ultrastructurally, the above mutations led to severe vacuolization and deformed nucleus in podocytes, torn and dissolved glomerular basement membrane, and diffuse foot process effacement. The patient with NUP85 mutation reached chronic kidney disease (CKD) stage 3 after 4 years follow-up, with exons 2-5 in-frame loss and a missense variant at c.511C > T, not affecting NUP85 expression but possibly weakened interaction with Seh1. Additionally, an extended endoplasmic reticulum (ER) tubule was readily observed under EM. Meanwhile, dilated ER was also found in two children with NUP160 mutations (c.3330 delA and c.2407 G > A; c.2241 + 1 (IVS17) G > T and c.3656 T > G), one of which has undergone kidney transplantation. Compound heterozygous variants in NUP107, c.1695 G > C and c.1360 C > T, were found in a 14-year-old girl initially diagnosed with CKD stage 5, with the former variant causing exon 19 skipping and early translation termination. c.1311 + 1(IVS15) G > A and c.1790 C > T were identified in the second affected girl, with the former causing exon 15 skipping and an in-frame loss of aa417-438, which disrupted the stability of NUP107 and interaction with NUP133.

CONCLUSIONS

Our findings expand the spectrum of phenotypes and genotypes of NUPs-associated SRNS and suggest its possible pathogenic mechanism in nuclear and ER homeostasis.

WT1 Gene Pathogenic Variants: Clinical Challenges and Treatment Strategies in Pediatric Nephrology-One Center Practice

Pathogenic variants in the Wilms' tumor suppressor gene 1 (WT1 gene) can lead to serious disorders within the kidney and urogenital system, including chronic kidney disease. There is still much uncertainty regarding the optimal management of diseases caused by WT1 dysfunction, posing a challenge for physicians caring for these patients. The aim of our study is to present experiences related to the course and treatment of patients with confirmed WT1 pathogenic variants. Data from seven patients (five girls, two boys), who were at the age of 4.8 ± 5.1 years (0.3-14 years) at their first admission and were treated between 1997-2022, were analyzed. The analysis included each patient's age at the day of diagnosis, anthropometric measurements, comorbidities, and laboratory and genetic test results, as well as their treatment, oncological procedures, and performed surgeries. Wilms' tumor was the first manifestation of the disease in three patients. Arterial hypertension was diagnosed in three patients, and anemia in four. Treatment of patients with nephrotic syndrome included glucocorticosteroid therapy (GCS), calcineurin inhibitors (CNIs), and mycophenolate mofetil (MMF). Nephrectomy was performed in five children, while kidney transplantation was carried out in two patients. An interdisciplinary approach to WT1 gene pathogenic variants, including early diagnosis, individualization, regular monitoring of treatment, and oncological vigilance, is crucial for improving prognosis and ensuring proper care for patients with nephrological manifestations of WT1 gene region disorders. Furthermore, for a comprehensive understanding of the scope of this disease and the development of effective therapy methods, continued research on the clinical manifestations of WT1 pathogenic variants is essential.

The efficacy and dynamic changes of immune function of rituximab with mycophenolate mofetil in the treatment of steroid-dependent /frequently relapsing nephrotic syndrome: a retrospective follow-up study

INTRODUCTION

Approximately 70%～90% of children with steroid-sensitive nephrotic syndrome (SSNS) will suffer from steroid dependency or frequent relapses, prompting the use of steroid-sparing agent. In this study, we investigate the efficacy and the characteristics of dynamic changes in immune function of two doses of rituximab (RTX) in the treatment of steroid-dependent/frequently relapsing nephrotic syndrome (SDNS /FRNS).

METHOD

Retrospective follow-up study was conducted in our hospital from June 2022 to September 2023. 7 children with SDNS /FRNS were allocated to intravenous 2 doses RTX (each dose 375mg/m2, 1 dose per week) and administered the standard oral dose of mycophenolate mofetil (MMF) (1000-1200/m2/d, divided into 2 doses) when B cells have recovered (≥ 5/ul). The study subjects after treatment were monitored for the efficacy and dynamic changes of immune function for 12 months.

RESULT

7 children with SDNS/FRNS who were treated RTX with MMF and followed up for 12 months have no relapse. The rate of B cell depletion (< 5/ul) was 100% at 1 week after the second dose of RTX treatment, and the rate of B cell recovery was 100% at 5-12 months after the first dose of RTX treatment. There was no significant difference with T cell subsets (CD3, CD4, CD8, CD4/CD8) at each follow-up time points (all P > 0.05). The count of NK cells was significantly higher than that of other groups at 1 week after the second dose (P < 0.05). The IgM level at 1 week after the second dose was significantly lower than that before treatment and 1 week after the first dose (P < 0.05). There were no significant differences with IgA, IgG, C3 and C4 before treatment, 1 week after the first dose and 1 week after the second dose (all P > 0.05).

CONCLUSION AND RECOMMENDATION

Administering two doses of RTX along with the standard dose of MMF has been effective in maintaining remission for children with SDNS/FRNS. B cell depletion can be achieved one week after the second dose of RTX treatment. NK cell proliferation may play a role in B cell depletion, and early B cell depletion may suppress the production of IgM. These findings require further validation through additional clinical trials and basic research.

Case Report: a novel variant in WT1 leads to focal segmental glomerulosclerosis and uterovaginal anomalies through exon skipping

Background

Podocytopathies are a varied set of renal diseases in which podocytes are unable to perform their typical filtration function within the glomerulus. This typically leads to edema, proteinuria, and hypoalbuminemia early in life. Among podocytopathies, focal segmental glomerulosclerosis (FSGS) is characterized by histology demonstrating segmental and focal sclerosis of the glomerular tuft. FSGS affects an estimated 1-20 per one million individuals and leads to significant morbidity and mortality related to renal failure. While FSGS can be attributed to many causes, such as drug reactions and infections, underlying pathogenic genetic variants play an increasingly well-recognized role in this disease.

Case

A 38-year-old 46,XX female patient of self-reported Cambodian ancestry was evaluated due to her history of atypical uterovaginal morphology. She had a history of hypertension and nephrotic range proteinuria that was diagnosed early in adulthood. A kidney biopsy at that time revealed FSGS. Following worsening renal function and subsequent end-stage renal disease (ESRD), she underwent a kidney transplant at 33 years of age. After kidney transplant, she presented with hematocolpos and was found to have distal vaginal atresia and an arcuate uterus. She underwent vaginoplasty and then had regular menses. She was noted to have persistently elevated follicle stimulating hormone levels, consistent with primary ovarian insufficiency, but with normal anti-Müllerian hormone levels. Assessment of her family history was suggestive of other individuals in her family with similar renal disease and uterine differences. Genetic analysis identified a WT1 variant (c.1338A>C; p. =) of uncertain significance that is also present in her similarly affected mother. To help clarify the potential impact of this variant, we completed a mini-gene assay to detect in vitro splicing changes in the presence of the WT1 variant sequence uncovered in this individual. This demonstrated resultant aberrant splicing that further supports the pathogenicity of the uncovered variant for this individual.

Conclusions

To our knowledge, this represents the first case of a podocytopathy with co-occurring uterovaginal anomalies due to exon skipping in WT1. The patient exhibited a severe course of chronic kidney dysfunction requiring a kidney transplant. Clinical RNA sequencing to clarify variants impacting splicing remains challenging due to tissue- specific gene expression for genes such as WT1, thus, research-based assays may be beneficial to understand the consequence of rare or previously uncharacterized variants.

Genotype-Phenotype Correlations in Denys-Drash Syndrome in Children

Introduction

Denys-Drash syndrome (DDS) is a rare disease typically associated with a triad of early onset nephrotic syndromes (NS), susceptibility to Wilms tumor (WT), and genitourinary structural defects. DDS is caused by Wilms' tumor suppression gene (WT1) variants, with the most frequent variants in exons 8 and 9. This study aimed to evaluate the long-term clinical outcomes and genotype-to-phenotype correlations in a large, multicenter cohort of children with typical DDS.

Methods

We conducted a national retrospective study of all children diagnosed with a pathogenic variant in WT1 exons 8 or 9 in France between 2000 and 2022.

Results

Fifty-eight children with DDS and variants in exons 8 (n = 23) and 9 (n = 35) of the WT1 gene were identified. Half of the children presented with NS (57% congenital, median age at presentation 0.3 years [interquartile range, IQR: 0.0-0.6]). Twenty-nine percent of children developed WT at a median age of 1.2 (0.5-2.2) years. Children with a variant in exon 8 developed NS much earlier than those with a variant in exon 9 (P = 0.0048), regardless of the type of genetic variation, leading to earlyier kidney failure (KF) (0.3 vs.1.4 years respectively; P = 0.0001) and higher mortality (35% vs 9%, P = 0.02). More than 90% of the truncating variants were located in exon 9 and were significantly associated with the occurrence of WT compared with the DNA-binding-site variants (P < 0.0015).

Conclusion

In our cohort, children's DDS clinical trajectory was associated with exon localization. In the era of genomic newborn screening, depicting genetic risk is of utmost importance for personalized patient care.

Differences in kidney prognosis between congenital and infantile nephrotic syndrome

BACKGROUND

More than half of patients with congenital nephrotic syndrome (CNS) or infantile nephrotic syndrome (infantile NS) have a monogenic aetiology. This study aimed to clarify differences in the clinical course, genetic background, and genotype-phenotype correlation between CNS and infantile NS.

METHODS

We enrolled patients who were diagnosed with CNS or infantile NS and referred to our hospital for genetic analysis and investigated the clinical characteristics and genetic background of patients with identified causative genes.

RESULTS

Among 74 patients enrolled, disease-causing genetic variants were detected in 50 patients. The median age for developing kidney failure in the genetic CNS (n = 33) and genetic infantile NS (n = 17) groups with monogenic variants was 13.2 and 19.0 months, respectively (P = 0.13). The age at developing kidney failure was significantly earlier in CNS patients with genes other than NPHS1 than in CNS patients with NPHS1 variants (1.0 vs. 31.0 months; P < 0.001). In patients with pathogenic variants other than NPHS1, there was a significant difference in the age at developing kidney failure between CNS and infantile NS patients (1.0 vs. 15.0 months; P < 0.001). Of patients with NPHS1 variants, no infants with NS had any truncating variants or developed kidney failure during follow-up.

CONCLUSIONS

The onset of CNS or infantile NS affects the kidney prognosis in patients with genetic nephrotic syndrome. Among patients with pathogenic variants in the same gene, patients with infantile NS may have a milder genotype and better prognosis than those with CNS.

Amino acid variants in the HLA-DQA1 and HLA-DQB1 molecules explain the major association of variants with relapse status in pediatric patients with steroid-sensitive nephrotic syndrome

BACKGROUND

Management of patients with steroid-sensitive nephrotic syndrome (SSNS) is challenging because of frequent relapses. Causal variants in the human leukocyte antigen (HLA) class II region that are associated with relapse remain undetermined.

METHODS

We collected a cohort of East Asian individuals comprising 206 pediatric patients with SSNS and 435 healthy controls from Southwest China. Ninety children with steroid-sensitive nephrotic syndrome without relapse (SSNSWR) and 116 children with steroid-dependent and/or frequent relapse nephrotic syndrome (SDNS/FRNS) were genotyped using Sanger sequencing. We then measured the transcriptional level, allele expression imbalance (AEI) and functional proteins of HLA-DQA1 and HLA-DQB1 in different stages of SDNS/FRNS.

RESULTS

rs1464545187 in ANKRD36 was associated with an approximately 1.69-fold greater risk for SSNSWR (P = 0.04; 95% confidence interval [CI], 1.05-2.72). Clustered risk variants in HLA-DQA1 and HLA-DQB1 were significantly associated with SDNS/FRNS (rs1047989: P = 2.26E-07, odds ratio [OR] = 2.25, 1.65-3.05; rs9273471: P = 5.45E-05, OR = 1.84, 1.37-2.46; HLA-DQB1*06:02: P = 0.017, OR = 0.19, 0.04-0.77). The genotype distributions of rs1047989, 2:171713702, rs1049123, rs9273471, and HLA-DQB1*06:02 in patients with SSNS were significantly different from those in healthy controls. rs1047989 (HLA-DQA1) was significantly associated with a greater number of infections at relapse in SDNS/FRNS patients (P = 0.045, OR = 6.79, 95% CI: 1.29-168.52). Flow cytometry showed that the proportion of cells expressing HLA-DQA1+/DQB1+ (HLA-DQA1+, P = 0.0046; HLA-DQB1+, P = 0.0045) was lowest in the relapse stage. In addition, the mRNA levels of HLA-DQA1 and HLA-DQB1 were significantly greater in the relapse group than in the remission group (HLA-DQA1, P = 0.03; HLA-DQB1, P = 0.002). No significant AEIs were detected in the different stages of SDNS/FRNS. The rs1047989 variant is likely to affect the structure and stability of HLA-DQA1.

CONCLUSION

rs1464545187 is a risk locus for SSNSWR but not SDNS/FRNS in Chinese children. Functional variations in HLA-DQA1 and HLA-DQB1 are implicated in regulating the immune response of SSNS patients, which may explain the typical triggering of SDNS/FRNS onset by infections.

Secondary congenital nephrotic syndrome complicated by acute mesenteric ischemia: A case report

Thromboembolic events are among the most serious, yet rare complications of nephrotic syndrome. While peripheral venous thrombosis and pulmonary embolism are the most common, superior mesenteric artery thrombosis is a rare but life-threatening occurrence. We present a case of severe cytomegalovirus (CMV) infection complicated by congenital nephrotic syndrome, leading to mesenteric ischemia.

Autoantibodies Targeting Proteasome Subunit Alpha Type 1 in Autoimmune Podocytopathies

Key Points

Serum anti-proteasome subunit alpha type 1 (PSMA1) autoantibodies were specifically elevated in the active phase of idiopathic nephrotic syndrome, which may assist in disease diagnosis and monitoring. Serum anti-PSMA1 antibodies could cause damage to the glomerular filtration barrier, which may be a pathogenic antibody of idiopathic nephrotic syndrome. PSMA1 played an important role in the maintenance of podocyte morphology and function.

Background

The antibody against proteasome subunit alpha type 1 (PSMA1) is a podocyte autoantibody in children with idiopathic nephrotic syndrome identified in our previous study. The aim of this study was to explore the characteristics of idiopathic nephrotic syndrome in children and the mechanism underlying its involvement in the development of idiopathic nephrotic syndrome.

Methods

The levels of serum anti-PSMA1 autoantibodies in children were detected through protein microarray and compared among different disease groups. The recombinant PSMA1 protein was injected subcutaneously and intraperitoneally into mice to observe glomerular morphology and function. The PSMA1-knockdown and PSMA1-overexpressing cell lines were constructed from mouse podocytes, and their cytoskeleton and function were analyzed. Homozygous zebrafish with psma1 knockout were observed.

Results

The levels of serum anti-PSMA1 autoantibodies were higher in children with idiopathic nephrotic syndrome and varied with urinary protein. In mice immunized with PSMA1, the presence of serum anti-PSMA1 autoantibody caused albuminuria and damage to the glomerular filtration membrane. Deficiency of PSMA1 impaired the podocyte cytoskeleton and physiological function. Complete deletion of psma1 caused edema, abnormal glomerular morphology, and effacement of foot processes in zebrafish.

Conclusions

PSMA1 played an important role in the maintenance of podocyte morphology and function.

IPNA consensus definitions for clinical trial outcomes in steroid-resistant nephrotic syndrome

Assessment of the true impact of therapeutic interventions is a challenge in the absence of universal, standardized definitions for clinical trial endpoints in children with kidney diseases. Steroid-resistant nephrotic syndrome (SRNS) is a difficult kidney disease to treat, with unremitting disease progressing to kidney failure. Currently, available therapies result in suboptimal cure rates. Clinical trials with innovative, targeted treatments will likely be conducted for this disease in the foreseeable future. An international consortium of the IPNA Best Practices and Standards Committee and the Pediatric Nephrology Expert Group of the conect4children (c4c) network developed through consensus, standardized, internationally acceptable definitions for trial outcomes for SRNS. The endpoint definitions were formulated for use with urine protein to creatinine ratios and estimated glomerular filtration rates. Definitions of complete remission, partial remission, non-remission of disease, reduction in proteinuria, kidney disease progression, kidney failure, and composite kidney outcome were refined using an iterative process until a consensus was achieved.

To biopsy or not to biopsy a teenager with typical idiopathic nephrotic syndrome? Start steroids first

It is well known that minimal change disease (MCD) and focal segmental glomerulosclerosis are the most common histopathology findings in children with idiopathic nephrotic syndrome. Moreover, several studies demonstrated that MCD is associated with high steroid-responsiveness and a low incidence of kidney failure, suggesting that routine kidney biopsy is not warranted. Over time, the indications for performing a kidney biopsy have become increasingly stringent, aiming to limit unnecessary invasive procedures in the paediatric population. The most recent guidelines state that a kidney biopsy is not usually necessary at disease onset. Still, it should be performed in case of atypical features suggestive of systemic diseases or glomerulonephritis and in case of steroid-resistance, to assess the different differential diagnoses, regardless of patient age. Moreover, it has been shown that the best prognostic marker in childhood nephrotic syndrome is response to treatment and that kidney histology is not accurate in predicting prognosis. Furthermore, a kidney biopsy is not necessary to predict the relapsing course. Notably, kidney biopsy is an invasive procedure and may lead to significant complications. Finally, novel non-invasive biomarkers have been validated or are in the process of being approved to guide differential diagnoses and thus limit the need for kidney biopsies in patients with typical nephrotic syndrome. In the following sections, we aim to explain why initiating steroid treatment as the initial approach in teenagers with typical nephrotic syndrome is a reasonable strategy. Additionally, we explore how kidney biopsy indications may be alleviated in this population.

Case report: Novel ACTN4 variant of uncertain significance in a pediatric case of steroid-resistant nephrotic syndrome requesting kidney transplantation

Background

Steroid-resistant nephrotic syndrome (SRNS) is a rare kidney disease commonly characterized histopathologically by focal and segmental glomerulosclerosis (FSGS) or minimal change disease. One-third of SRNS-FSGS cases are attributed to a genetic cause ultimately leading to end-stage kidney disease (ESKD) during childhood or adulthood. ACTN4 variants, although rare, typically manifest in early adulthood as SRNS-FSGS with autosomal dominant inheritance pattern and are associated with variable progression toward ESKD.

Case–diagnosis/treatment

A 10-year-old Chilean male patient, born to a complicated pregnancy without any history of prenatal care, was incidentally found to have mild proteinuria during pre-surgery analysis. He was diagnosed with nephrotic syndrome and treatment with prednisone was started, but 12 months later, he persisted with hyperlipidemia, hypoalbuminemia, and proteinuria. Within a few weeks, proteinuria rapidly increased, and a kidney biopsy exhibited FSGS features. At the age of 12, he reached ESKD and initiated peritoneal dialysis, experiencing an episode of posterior reversible encephalopathy syndrome. Exome sequencing identified a novel variant of uncertain significance (VUS), ACTN4 c.625_633del that predicted the in-frame deletion p.L209_E211del in a highly conserved functional domain. He requested to be considered for kidney transplantation and the VUS in ACTN4 was re-analyzed to assess potential risks, resulting in a reclassification as likely pathogenic (PM1+PM2+PM4 criteria). At 14 years old, he received a deceased donor kidney allograft without recurrence during the subsequent 5 months.

Conclusions

Identifying VUS is a recurring challenge in routine clinical genetics, particularly for patients with rare diseases or atypical phenotypes in underrepresented populations. This case underscores the benefit of timely genetic diagnosis taking into account the patient's request. VUS reassessment becomes more relevant when considering a kidney transplant not only as an appropriate procedure, but as the therapy of choice, especially considering the patient's history of complications with variable long-term consequences.

Molecular signaling pathways in doxorubicin-induced nephrotoxicity and potential therapeutic agents

Doxorubicin (DOX), an anthracycline chemotherapeutic agent, is extensively utilized in the clinical management of both solid and hematological malignancies. Nevertheless, the clinical application of this treatment is significantly limited by adverse reactions and toxicity that may arise during or after administration. Its cytotoxic effects are multifaceted, with cardiotoxicity being the most prevalent side effect. Furthermore, it has the potential to adversely affect other organs, including the brain, kidneys, liver, and so on. Notably, it has been reported that DOX may cause renal failure in patients and there is currently no effective treatment for DOX-induced kidney damage, which has raised a high concern about DOX-induced nephrotoxicity (DIN). Although the precise molecular mechanisms underlying DIN remain incompletely elucidated, prior research has indicated that reactive oxygen species (ROS) are pivotal in this process, triggering a cascade of detrimental pathways including apoptosis, inflammation, dysregulated autophagic flux, and fibrosis. In light of these mechanisms, decades of research have uncovered several DIN-associated signaling pathways and found multiple potential therapeutic agents targeting them. Thus, this review intends to delineate the DIN associated signaling pathways, including AMPK, JAKs/STATs, TRPC6/RhoA/ROCK1, YAP/TEAD, SIRTs, Wnt/β-catenin, TGF-β/Smad, MAPK, Nrf2/ARE, NF-κB, and PI3K/AKT, and to summarize their potential regulatory agents, which provide a reference for the development of novel medicines against DIN.

Emerging Role of SH3BP2 as Regulator of Immune and Nonimmune Cells in Nephrotic Syndrome

Background

Minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are major forms of nephrotic syndrome that remain difficult to treat. MCD and FSGS have distinct but also overlapping clinical, histological, metabolic, and molecular features. Effective use of immunosuppressive drugs, activated immune cells, altered cytokine profiles, and upregulated signaling pathways suggest a link between immune dysfunction and nephrotic syndrome, but the exact mechanism of immunopathogenesis is unclear. Immune dysfunction is an area of ongoing research for identifying novel molecular targets for treating nephrotic syndrome. However, the available animal models do not directly address the role of immune dysfunction in nephrotic syndrome.

Summary

Genetic analysis indicates that heterogeneous genes related to the podocyte-specific proteins may indirectly cause damage to filtration barrier and influence the onset and progression of nephrotic syndrome. SH3BP2 protein regulates several pathways through its role as a scaffold for many signaling mediators and enzymes. SH3BP2 is expressed in immune as well as in nonimmune cells including podocytes. The role of SH3BP2 is discussed in the context of cells and molecules of adaptive and innate immune systems. Available information on the importance of SH3BP2 in diseases other than nephrotic syndrome and its role in the immunopathogenesis of human nephrotic syndrome are summarized. We outline the key features of a transgenic mouse strain with a gain-in-function mutation (Sh3bp2 KI/KI ) as a potential model to study immunopathogenesis of nephrotic syndrome.

Key Messages

Non-receptor, non-catalytic proteins such as SH3BP2 are a novel group of proteins that regulate the innate and adaptive immune responses in nephrotic syndrome. New evidence suggests a critical role of SH3BP2 in immunopathogenesis of nephrotic syndrome. Our recent results demonstrate that transgenic mice (Sh3bp2 KI/KI ) with a gain-in-function mutation will likely be a unique model to study immunopathogenesis of nephrotic syndrome.

Mechanistic Insights Into Redox Damage of the Podocyte in Hypertension

Podocytes are specialized cells within the glomerular filtration barrier, which are crucial for maintaining glomerular structural integrity and convective ultrafiltration. Podocytes exhibit a unique arborized morphology with foot processes interfacing by slit diaphragms, ladder-like, multimolecular sieves, which provide size and charge selectivity for ultrafiltration and transmembrane signaling. Podocyte dysfunction, resulting from oxidative stress, dysregulated prosurvival signaling, or structural damage, can drive the development of proteinuria and glomerulosclerosis in hypertensive nephropathy. Functionally, podocyte injury leads to actin cytoskeleton rearrangements, foot process effacement, dysregulated slit diaphragm protein expression, and impaired ultrafiltration. Notably, the renin-angiotensin system plays a pivotal role in podocyte function, with beneficial AT2R (angiotensin receptor 2)-mediated nitric oxide (NO) signaling to counteract AT1R (angiotensin receptor 1)-driven calcium (Ca2+) influx and oxidative stress. Disruption of this balance contributes significantly to podocyte dysfunction and drives albuminuria, a marker of kidney damage and overall disease progression. Oxidative stress can also lead to sustained ion channel-mediated Ca2+ influx and precipitate cytoskeletal disorganization. The complex interplay between GPCR (G-protein coupled receptor) signaling, ion channel activation, and redox injury pathways underscores the need for additional research aimed at identifying targeted therapies to protect podocytes and preserve glomerular function. Earlier detection of albuminuria and podocyte injury through routine noninvasive diagnostics will also be critical in populations at the highest risk for the development of hypertensive kidney disease. In this review, we highlight the established mechanisms of oxidative stress-mediated podocyte damage in proteinuric kidney diseases, with an emphasis on a hypertensive renal injury. We will also consider emerging therapies that have the potential to selectively protect podocytes from redox-related injury.

Childhood idiopathic nephrotic syndrome: recent advancements shaping future guidelines

Childhood idiopathic nephrotic syndrome is an important pediatric kidney disease associated with significant morbidities and even mortality. Several guidelines have been developed to standardize the terminology and patient care among the pediatric nephrology community. Since the publication of these guidelines, there have been major breakthroughs in the disease management and the understanding of underlying pathogenesis through multi-omics investigations, including the identification of anti-nephrin autoantibodies, genetic susceptibility loci, and the pathogenic role of B cell subsets. In this educational review, we summarize the recent major advancements in idiopathic nephrotic syndrome and attempt to provide potential therapeutic approaches in both steroid-sensitive and steroid-resistant nephrotic syndrome that may shape future guideline development.

Clinical Implementation of Nephrologist-Led Genomic Testing for Glomerular Diseases in Singapore: Rationale and Protocol

INTRODUCTION

The early diagnosis and appropriate treatment of monogenic glomerular diseases can reduce kidney failure, avoid unnecessary investigations such as kidney biopsies and ineffective treatment with immunosuppressants, guide transplant decisions, and inform the genetic risks of their family members. Yet, genetic testing for kidney disease is underutilized in Singapore. We aimed to implement a nephrologist-led genetic service and evaluate the acceptance, adoption, utility, and cost-effectiveness of genetic testing for monogenic glomerular disease in Singapore.

METHODS

We will perform a prospective, multi-centre, type II hybrid effectiveness-implementation study with a post-design to evaluate both implementation and clinical outcomes of nephrologist-led genetic testing for suspected genetic glomerular kidney diseases. The multi-disciplinary implementation team will train "genetic nephrologists" to provide pre- and post-test counselling, order targeted exome panel sequencing for suspected glomerular kidney diseases (persistent microscopic haematuria and/or albuminuria or proteinuria in the absence of known causes, steroid-resistant primary nephrotic syndrome, apparent familial IgA nephropathy, or chronic kidney disease with no apparent cause), and interpret genetic test results; create workflows for patient referral, evaluation and management, and discuss genetic results at regular genomic board meetings. The outcomes are acceptance, appropriateness and adoption among patients and nephrologists, utility (proportion of patients who received genetic testing and have a confirmed diagnosis of genetic glomerular disease), and cost-effectiveness.

CONCLUSION

This study will create and evaluate a nephrologist-led genetic service, develop an efficient variant curation process, and inform future recommendations on the optimal referral and genetic testing strategy for monogenic glomerular disease in Singapore. This will facilitate the future mainstreaming of genetic testing that will enable precision medicine in kidney care.

A multicenter study investigating the genetic analysis of childhood steroid-resistant nephrotic syndrome: Variants in COL4A5 may not be coincidental

This study aimed to discuss the pathogenic hereditary factors of children with steroid-resistant nephrotic syndrome (SRNS) in Guangxi, China. We recruited 89 patients with SRNS or infantile NS from five major pediatric nephrology centers in Guangxi, and conducted a retrospective analysis of clinical data. Whole-exome sequencing analysis was also performed on all patients. The risk of progression to chronic kidney disease (CKD) was assessed using the Kaplan-Meier method and Cox proportional hazards model. The study included 69 male and 20 female participants from 86 distinct families, with the median age of disease onset being 48 months (interquartile range: 24-93). Overall, 24.7% had a family history of SRNS, whereas 13.5% exhibited extra-kidney manifestations. We identified disease-causing variants in 24.7% (22/89) of patients across eight screened genes. The most frequently detected variant was found in COL4A5, followed by NPHS2 (5.6%), NPHS1 (2.2%), PAX2 (2.2%), WT1 (1.1%), LMX1B (1.1%), NUP105 (1.1%), and COL4A6 (1.1%). Twelve of the 26 pathogenic variants were determined to be de novo. Based on gene detection results, pathogenic variants were categorized into two groups: identified and unidentified variants. The identified variant group demonstrated a significant association with positive family history, steroid resistant-style, and response to immune therapy (P<0.001). Patients with the identified genetic variant were approximately ten times more likely to develop CKD (P<0.001) than those in the unidentified group at the last follow-up. Kidney biopsy was performed on 66 patients, and minimal change disease was the most prevalent histopathological diagnosis (29 cases; 32.6%). These findings suggest that children diagnosed with SRNS exhibit a diverse range of genetic alterations. We identified the COL4A5 variant as the predominant genetic abnormality and a low frequency of NPHS1 gene involvement in these children. Gene variants may serve as an independent predictor for SRNS progression to CKD.

Steroid-Resistant Nephrotic Syndrome Is Associated With a Unique Genetic Profile in a Highly Admixed Pediatric Population

Introduction

The profile of genetic and nongenetic factors associated with progression to kidney failure (KF) in steroid-resistant nephrotic syndrome (SRNS) is largely unknown in admixed populations.

Methods

A total of 101 pediatric patients with primary SRNS were genetically assessed targeting Mendelian causes and APOL1 status with a 62-NS-gene panel or whole exome sequencing, as well as genetic ancestry. Variant pathogenicity was evaluated using the American College Medical of Genetics and Genomics (ACMG) criteria.

Results

Focal segmental glomerulosclerosis (FSGS) was diagnosed in 54% of patients whereas familial disease was reported by 13%. The global genetic ancestry was 65% European, 22% African, 10.5% Native American, and 2% East-Asian, while 96% of cases presented with the first 3 components. APOL1 high-risk genotypes were identified in 8% of families and causative Mendelian variants in 12%: NPHS1 = 3, NPHS2 = 3, PLCE1 = 2, WT1 = 2, COQ2 = 1, and CUBN = 1. Two novel causative variants arose in the Native American background. The percentage of African genetic ancestry did not associate with the number of APOL1 risk alleles. Forty-four percent of all patients progressed to KF. Mendelian forms and APOL1 high-risk genotypes were associated with faster progression to KF. Cox regression analyses revealed that higher non-European genetic ancestry, self-declared non-White ethnicity, age of onset <1 year or ≥9 years, and non-minimal change disease (MCD) histology associated with higher risk of KF, independently of genetic findings.

Conclusion

Mendelian variants and APOL1 high-risk genotype compose a unique causative genetic profile associated with pediatric SRNS in this highly admixed population, accounting for approximately 20% of families. This ancestry pattern is consistent with the identification of APOL1 high-risk genotypes in children with low proportion of African genetic ancestry. Self-declared ethnicity, age of manifestation and histology were independently associated with the risk of KF.

In steroid-resistant nephrotic syndrome that meets the strict definition, monogenic variants are less common than expected

BACKGROUND

In patients with steroid-resistant nephrotic syndrome (SRNS), the presence of monogenic variants influences therapeutic strategies. Large cohort studies reported the detection of monogenic variants in approximately 30% of patients with SRNS. However, these cohorts included many patients, such as those with symptomatic proteinuria, who did not meet the strict diagnostic criteria for pediatric nephrotic syndrome (NS). Therefore, we investigated the proportion of causative monogenic variants detected in patients who strictly met the diagnostic criteria of SRNS and explored their clinical characteristics.

METHODS

We examined pediatric SRNS cases with genetic analysis conducted in our hospital. Cases satisfying all of the following criteria were included: (1) age at onset 1-18 years, (2) serum albumin at onset ≤ 2.5 g/dl, (3) persistent heavy proteinuria, and (4) no complete remission after 4 weeks of steroid monotherapy.

RESULTS

The proportion of detected monogenic variants was 12% (22/185) among all patients. The proportion was only 7% (9/129) in patients with edema at disease onset compared with 38% (9/24) in those without (p < 0.0001). Monogenic variants were rare in patients with acute kidney injury associated with NS (1% (1/11)) or a history of complete remission (4% (2/51)).

CONCLUSIONS

Our study revealed a monogenic cause in 12% of individuals with strictly defined SRNS, a much smaller proportion than previously reported. The presence or absence of edema at the onset was an important factor to distinguish SRNS with monogenic cause from SRNS without. Our results provide further evidence of the SRNS types attributable to monogenic causes.

Advances in Diagnosis and Treatment of Inherited Kidney Diseases in Children

Background

Inherited kidney diseases (IKDs) in children pose unique diagnostic and therapeutic challenges. IKD significantly impact patient quality of life, morbidity, mortality, and cost to the healthcare system. With over 150 genetic abnormalities, they account for approximately 30% of cases requiring renal replacement therapy. There is an urgent need to advance both diagnosis and treatment strategies. In this review, we present recent advances in diagnosis and treatment for facilitating personalized treatment approaches.

Summary

The diagnostic landscape for IKDs have evolved significantly, emphasizing precise genetic identification and classification of these disorders. Recent advancements include the refinement of genetic testing techniques, such as whole exome sequencing, which has improved the accuracy of diagnosing specific diseases and facilitated early intervention strategies. Additionally, this review categorizes IKDs based on genetic abnormalities and clinical manifestations, enhancing understanding and management approaches. Finally, it summarizes the corresponding treatment, and lists the application of emerging therapeutic options such as gene therapy and organoids, which show promise in transforming treatment outcomes.

Key Messages

This review summarizes the common types of IKDs in children, including their diagnosis and treatment advances, and provides an update on the status of gene therapy development for these disorders.

An international, multi-center study evaluated rituximab therapy in childhood steroid-resistant nephrotic syndrome

The efficacy and safety of rituximab in childhood steroid-resistant nephrotic syndrome (SRNS) remains unclear. Therefore, we conducted a retrospective cohort study at 28 pediatric nephrology centers from 19 countries in Asia, Europe, North America and Oceania to evaluate this. Children with SRNS treated with rituximab were analyzed according to the duration of calcineurin inhibitors (CNIs) treatment before rituximab [6 months or more (CNI-resistant) and under 6 months]. Primary outcome was complete/partial remission (CR/PR) as defined by IPNA/KDIGO guidelines. Secondary outcomes included kidney failure and adverse events. Two-hundred-forty-six children (mean age, 6.9 years; 136 boys; 57% focal segmental glomerulosclerosis, FSGS) were followed a median of 32.4 months after rituximab. All patients were in non-remission before rituximab. (146 and 100 children received CNIs for 6 month or more or under 6 months before rituximab, respectively). In patients with CNI-resistant SRNS, the remission rates (CR/PR) at 3-, 6-, 12- and 24-months were 26% (95% confidence interval 19.3-34.1), 35.6% (28.0-44.0), 35.1% (27.2-43.8) and 39.1% (29.2-49.9), respectively. Twenty-five patients were in PR at 12-months, of which 22 had over 50% reduction in proteinuria from baseline. The remission rates among children treated with CNIs under 6 months before rituximab were 42% (32.3-52.3), 52% (41.8-62.0), 54% (44.3-64.5) and 60% (47.6-71.3) at 3-, 6-, 12-, and 24-months. Upon Kaplan-Meier analysis, non-remission and PR at 12-months after rituximab, compared to CR, were associated with significantly worse kidney survival. Adverse events occurred in 30.5% and most were mild. Thus, rituximab enhances remission in a subset of children with SRNS, is generally safe and CR following rituximab is associated with favorable kidney outcome.

Anti-slit diaphragm antibodies on kidney biopsy identify pediatric patients with steroid-resistant nephrotic syndrome responsive to second-line immunosuppressants

Podocytopathies represent a group of glomerular disorders associated with minimal changes (MC) or focal segmental glomerulosclerosis (FSGS) lesion patterns at biopsy and heterogeneous responses to steroids. Anti-nephrin antibodies were previously found in such patients, suggesting an autoimmune form of podocytopathy. High resolution confocal microscopy on kidney biopsies of a cohort of 128 pediatric patients revealed localization of IgG along the slit diaphragm in 30% of patients with MC and 25% of those with FSGS, but not in other lesion patterns. Anti-nephrin IgG ELISA assay in the serum and stimulated emission depletion microscopy of kidney biopsies showed IgG-nephrin co-localization only in 77.8% of cases. Similar observations were obtained in a cohort of 48 adult patients with MC or FSGS at kidney biopsy, where IgG-nephrin colocalization was only 44.4%, suggesting the existence of autoantibodies binding to other slit proteins. Patients with anti-slit antibodies showed nephrotic syndrome at onset in 94.4% of cases. Patients with primary steroid-resistance had anti-slit antibodies in 27%, while those with secondary steroid-resistance in 87.5% of cases, irrespective of the histopathological lesion pattern. Steroid-resistant patients with anti-slit antibodies responded to second-line immunosuppressants in 92.3% vs. only 20% of patients that were anti-slit negative. No patient with anti-slit antibodies developed kidney failure vs. 51.7% of those negative for antibodies (66.7% with a genetic cause and 41.2% with a non-genetic cause). Thus, the detection of anti-slit antibodies can identify patients with an autoimmune podocytopathy responsive to treatment with second-line immunosuppressants, irrespective of the histopathological lesion pattern at biopsy.

K acetyltransferase 2B (KAT2B) variants can be responsible for early onset steroid-resistant nephrotic syndrome

In children, 15% of nephrotic syndromes are steroid-resistant (SRNS); approximately 30% of early onset SRNS have a genetic origin, with more than 100 causal genes described so far. SRNS can be syndromic, if associated with signs and symptoms affecting other organs or systems, such as the central nervous system, the heart or the eyes. Patients with SRNS are at high risk of chronic kidney disease and progressive renal failure, and as such need multidisciplinary care, centred on renal protection. Recently, K acetyltransferase 2B (KAT2B) loss of function was identified as a risk factor for morphological and functional defects in Drosophila nephrocytes; in vitro knockdown of KAT2B also impaired the adhesion and migration ability of human podocytes.Here we provide the first clinical description of a family affected by a loss of function mutation of KAT2B Clinically, both siblings presented with early onset SRNS and bilateral cataract, without neurological or heart defects. Renal function was maintained in the teenage years; nephrotic-range proteinuria was insensitive to immunosuppressive therapies. Therefore, mutations of KAT2B should be sought in patients with unexplained syndromic SRNS affecting the eye.

Rituximab Administration to Treat Nephrotic Syndrome in Children: 2-Year Follow-Up

BACKGROUND

Steroid-sensitive nephrotic syndrome (SSNS) and steroid-resistant nephrotic syndrome (SRNS) significantly affect children's quality of life. There are frequent relapses in SSNS and progression in SRNS. IPNA guidelines suggest that monoclonal antibodies like rituximab (RTX) are promising treatments.

OBJECTIVE

This study aims to evaluate the long-term efficacy and safety of rituximab administration in children with SSNS, encompassing FRNS and SDNS, and SRNS over a two-year follow-up period, facilitating individualized management.

METHODS

We conducted an open-label, multicenter, randomized, and patient-oriented study (RICHNESS), involving children aged 3-18 with SRNS (18) and SSNS (11) undergoing 2 years continuous RTX therapy. The primary outcome was complete/partial remission (CR/PR), as defined by IPNA/KDIGO guidelines, at 6, 12, 18, and 24 months on RTX; secondary outcomes included adverse events. Key endpoints included the estimated glomerular filtration rate (eGFR), the albumin-to-creatinine ratio (ACR), CD20 levels, IgG levels, and the incidence of infections. Kidney biopsies were performed in 94% of SRNS patients. RTX was administered every 6-9 months, depending on CD20 levels, IgG levels, and the presence of infections. The eGFR and ACR were assessed every 6 months.

RESULTS

Some 31 children were selected for RTX treatment. Overall, 2 experienced severe allergic reactions, leading to their exclusion from the final analysis of 29 children. In the SSNS group, all children achieved and maintained complete remission within 2 years. Remission rates in the SRNS group ranged from 39% (RR 0.78; 95% CI: 16.4-61.4%, NNT 9) at the 6th month to 72% (RR 1.44; 95% CI: 51.5-92.9%) over the 2-year follow-up period due to continuous RTX therapy. The median duration of RTX use was 26.1 months, with a median cumulative dose of 1820 mg/m2. Adverse reactions and complications were presented by mild infusion-related reactions in 3 children (10.3%), severe allergic reactions in 2 children (6.2%), hypogammaglobulinemia in 7 children (24%), infections in 3 children (10.3%), severe destructive pneumonia in 1 child, recurrent respiratory infections in 2 children, and neutropenia in 1 child (3.44%).

CONCLUSIONS

RTX was tolerated well, and proved highly effective as a steroid-sparing agent, offering potential in terms of stopping relapses and minimizing steroid-related side effects. It also demonstrated efficacy in slowing progression in SRNS, indicating potential for use in ACR reduction and renal function restoration, but requires careful use given potential severe allergic reactions and infectious complications. Further studies should focus on long-term cost-effectiveness and deferred side effects.

Clinical characteristics and prognosis of steroid-resistant nephrotic syndrome in children: a multi-center retrospective study

BACKGROUND

This study investigated the factors influencing the prognosis of children with steroid-resistant nephrotic syndrome (SRNS) in patients from the Guangxi region.

METHODS

We retrospectively analyzed clinical and pathological data of 279 patients with SRNS from six tertiary hospitals in Guangxi. Clinical data were compared between initial (I-SRNS) and secondary (S-SRNS) steroid resistance subgroups and Cox regression analysis was used to determine risk factors for chronic kidney disease (CKD) and CKD stage 5 (CKD5) in patients with SRNS.

RESULTS

The median age of onset was 54 months. Thirty-three patients had extra-kidney manifestations. Fifty-two, 24, 57, 33, and 41 patients had hypertension, acute kidney injury, vitamin D deficiency, high intraocular pressure, and dwarfism, respectively. One hundred eighty-two and 92 patients had I-SRNS and S-SRNS, respectively. There were significant differences in sex, ethnicity, family history, incidence of hematuria, clinical classification, efficacy of immune agents, and prognosis between groups (P < 0.05). Among the 279 cases of SRNS, 239 had normal kidney function, 37 developed CKD, and 16 had CKD5. An increase in serum creatinine level (HR = 1.003) was significantly associated with CKD in children with SRNS, and effective immunosuppressant therapy decreased the CKD risk (HR = 0.168). Patients with increased serum creatinine levels (HR = 1.003) and acute kidney injury (HR = 4.829) were more likely to progress to CKD5.

CONCLUSIONS

Children with S-SRNS showed a higher response to immunosuppressants than those with I-SRNS. Effective immunosuppressant therapy was found to protect against CKD, whereas increased acute kidney injury was an independent risk factor for CKD5.

Management and long-term outcome of recurrent idiopathic FSGS in pediatric kidney transplant recipients

Focal segmental glomerulosclerosis (FSGS) is a major cause of pediatric kidney failure. Most cases of FSGS in children are idiopathic and have a high risk of post-transplantation recurrence and graft loss. Common treatments for recurrent FSGS (rFSGS) post-transplantation include plasmapheresis, immunoadsorption, and/or immunomodulatory therapy. This study retrospectively evaluated the efficacy and safety of early plasmapheresis followed by rituximab for inducing and maintaining remission in rFSGS. Between 2014 and 2023, 8 of 65 pediatric kidney transplant recipients at our center were diagnosed with idiopathic FSGS. rFSGS was diagnosed based on nephrotic range proteinuria with no other cause and managed with plasmapheresis. Rituximab therapy was used for those who did not achieve complete remission with prolonged plasmapheresis or remained plasmapheresis dependent. 6 of 8 (75%) transplant recipients with idiopathic FSGS experienced rFSGS. All patients achieved partial or complete remission with plasmapheresis, with response times ranging from 8 to 379 days (median 13 days). Rituximab therapy was introduced for 5 plasmapheresis-dependent patients, leading to sustained remission and cessation of plasmapheresis in 3 patients, while 2 showed improved proteinuria and reduced plasmapheresis frequency. Adverse effects included rituximab-induced serum sickness in one patient and one mild allergic reaction. One patient experienced graft loss due to humoral rejection, but no grafts were lost to rFSGS, and all other grafts remained functional over an average follow-up of 50 months. Early plasmapheresis followed by rituximab therapy effectively induces remission in most post-transplantation rFSGS cases, is well tolerated, and prevents graft loss. Larger studies are needed to confirm these findings.

Ambulatory blood pressure monitoring in Egyptian children with nephrotic syndrome: single center experience

BACKGROUND

Hypertension (HTN), especially masked hypertension, is one of the cardiovascular consequences of nephrotic syndrome. Masked hypertension cannot be identified during routine follow-up visits and adversely effects the patients' cardiac function. The purpose of this study was to use ambulatory blood pressure monitoring (ABPM) to evaluate the blood pressure status of children with nephrotic syndrome.

METHODS

Ninety children with nephrotic syndrome (NS) participated in this cross-sectional study, which was carried out at Cairo University Children Hospital's nephrology clinic (CUCH). A sphygmomanometer was used in the clinic to measure blood pressure, and a Meditech monitor was used for 24-hour ambulatory blood pressure monitoring (ABPM). Interventricular septum (IVS) was measured, and heart functions were evaluated, using echocardiography.

RESULTS

Two groups comprised the included patients: Group1 (n = 70): HTN group included masked and ambulatory hypertension, and Group 2 (n = 20): non-HTN group included normal blood pressure, white coat HTN and well controlled HTN, 35% of the studied cohort (n = 32/90) had masked HTN.The serum urea was significantly higher in HTN group than non-HTN group with p-value: 0.047, while the serum albumin was significantly lower in HTN group than non-HTN group with p-value: 0.017. The cut-off point of 9.9, the sensitivity and specificity of serum urea to predict the occurrence of hypertension in NS patients was 92.9% and 35% respectively, with p-value : 0.024 and 95% CI (0.534-0.798). The z score of IVS is significantly higher in group 1 (2.5 ± 1.2) when compared to group 2 (1.7 ± 2.1) with p-value: 0.025 and Among group 1, it was noticed that 74% (n = 52/70) of them were systolic non-dipper, also it was observed that the mean serum potassium and cholesterol were significantly higher among systolic non-dipper when compared with systolic dipper patients with p-values: 0.045 and 0.005 respectively.

CONCLUSION

Children with nephrotic syndrome are particularly vulnerable to experience ambulatory hypertension and masked hypertension, which may adversely impact their cardiac condition because they are not detectable by standard blood pressure readings at the clinic.

Clinical Characteristics, Pathological Features and Treatment Outcomes of Children With Nephrotic Syndrome at Princess Marina Hospital, Botswana

Objective. Despite the remarkable progress made in the understanding and treatment of childhood nephrotic syndrome (NS), a lot is still unknown about its epidemiology in many African countries. This study sought to determine the clinicopathological features and treatment outcomes of children with NS at the largest tertiary hospital in Botswana. Methods. A retrospective study of 26 children with NS treated from 2009 to 2014 was conducted. Results. Mean age at presentation was 5.96 ± 3.06. Hematuria was found in 92.3%, low C3 in 26.7%, high creatinine in 19.2% and hypertension in 46.2% of the patients. 92.3% had primary NS out of which 23.1% had familial NS. HIV, tuberculosis and hepatitis B infections were diagnosed in 3.85%, 9.09% and 4.16% respectively. 69.2% had steroid-resistant nephrotic syndrome, focal segmental glomerulosclerosis (SRNS-FSGS). Conclusion. The frequency of primary SRNS-FSGS and familial SRNS appears to be much higher in Botswana highlighting the possibility of genetic causes.

Efficacy of rituximab and risk factors for poor prognosis in patients with childhood-onset steroid-resistant nephrotic syndrome: a multicenter study

BACKGROUND

The efficacy of rituximab in steroid-resistant nephrotic syndrome (SRNS) is controversial. We previously reported that rituximab in combination with methylprednisolone pulse therapy (MPT) and immunosuppressants was associated with favorable outcomes. We determined risk factors for poor response following rituximab treatment, which remains unknown.

METHODS

This retrospective study included 45 patients with childhood-onset SRNS treated with rituximab across four pediatric kidney facilities. Treatment effects were categorized as complete remission (CR), partial remission (PR), and no remission (NR) at one year after rituximab treatment. The primary outcome was the rate of CR, PR, and NR. Risk factors for non-CR were calculated with multivariate logistic regression. Adverse events and the relationship between disease status at one year and long-term prognosis were also evaluated.

RESULTS

The rates of CR, PR, and NR at one year were 69%, 24%, and 7%, respectively. The median time from rituximab administration to CR was 90 days. The median follow-up period after rituximab administration was 7.4 years. In multivariate analysis, significant risk factors for poor response were the pathologic finding of focal segmental glomerular sclerosis and a long interval between SRNS diagnosis and rituximab administration. The rates of CR were 90.3% and 21.4% in patients receiving rituximab within and after 6 months following SRNS diagnosis, respectively (p < 0.001). Five patients developed chronic kidney disease stage G5, including 2 of the 11 patients with PR and all 3 patients with NR, whereas none of the 31 patients with CR developed chronic kidney disease stage G5.

CONCLUSION

Early administration of rituximab in combination with MPT and immunosuppressants might achieve favorable outcomes in patients with SRNS.

The impact of severe nephrotic syndrome on thyroid function, nutrition and coagulation

Background

Nephrotic syndrome (NS) is characterized by urinary loss of proteins, including hormones and their carrier proteins, potentially resulting in endocrine disorders. This study aimed to assess thyroid dysfunction frequency and potential implications in NS.

Methods

In this case-control study, patients with severe NS (serum albumin ≤2.5 g/dl) and controls without proteinuria were evaluated for thyroid, haemostatic and nutritional parameters, including body composition.

Results

A total of 42 nephrotic and 40 non-proteinuric patients were enrolled. The NS group showed higher thyroid-stimulating hormone and lower free hormones, corresponding to a higher frequency of both euthyroid sick syndrome {ESS; 36% versus 5%; odds ratio [OR] 10.6 [95% confidence interval (CI) 2.2-50.0]} and hypothyroidism [31% versus 5%; OR 8.5 (95% CI 1.8-40.7)] compared with the control group. Levothyroxine supplementation was required for 11 NS patients (26% of the NS group). In addition, compared with control individuals, NS patients exhibited lower lean tissue mass and a trend towards hypercoagulability, which was evidenced by higher levels of most coagulation factors and fibrinolysis inhibitors, and reduced endogenous anticoagulants activities. Furthermore, NS patients with ESS presented with a 10.4 kg (95% CI -18.68 to -2.12) lower lean tissue mass. Those with hypothyroidism had significantly reduced activity of coagulation factor X [by -30% (95% CI -47 to -13)] and protein S [by -27% (95% CI -41 to -13)] compared with euthyroid NS individuals.

Conclusions

Thyroid dysfunction is common in severe NS, often necessitating levothyroxine supplementation, which supports routine thyroid workup. A potential link between thyroid, nutritional and coagulation disorders in NS requires further investigation.

WT1-related disorders: more than Denys-Drash syndrome

Historically, specific mutations in WT1 gene have been associated with distinct syndromes based on phenotypic characteristics, including Denys-Drash syndrome (DDS), Frasier syndrome (FS), Meacham syndrome, and WAGR syndrome. DDS is classically defined by the triad of steroid-resistant nephrotic syndrome (SRNS) onset in the first year of life, disorders of sex development (DSD), and a predisposition to Wilms tumor (WT). Currently, a paradigm shift acknowledges a diverse spectrum of presentations beyond traditional syndromic definitions. Consequently, the concept of WT1-related disorders becomes more precise. A genotype-phenotype correlation has been established, emphasizing that the location and type of WT1 mutations significantly influence the clinical presentation, the condition severity, and the chronology of patient manifestations. Individuals presenting with persistent proteinuria, with or without nephrotic syndrome, and varying degrees of kidney dysfunction accompanied by genital malformations should prompt suspicion of WT1 mutations. Recent genetic advances enable a more accurate estimation of malignancy risk in these patients, facilitating a conservative nephron-sparing surgery (NSS) approach in select cases, with a focus on preserving residual kidney function and delaying nephrectomies. Other key management strategies include kidney transplantation and addressing DSD and gonadoblastoma. In summary, recent genetic insights underscore the imperative to implement individualized, integrated, and multidisciplinary management strategies for WT1-related disorders. This approach is pivotal in optimizing patient outcomes and addressing the complexities associated with these diverse clinical manifestations.

Urine-derived podocytes from steroid resistant nephrotic syndrome patients as a model for renal-progenitor derived extracellular vesicles effect and drug screening

BACKGROUND

Personalized disease models are crucial for evaluating how diseased cells respond to treatments, especially in case of innovative biological therapeutics. Extracellular vesicles (EVs), nanosized vesicles released by cells for intercellular communication, have gained therapeutic interest due to their ability to reprogram target cells. We here utilized urinary podocytes obtained from children affected by steroid-resistant nephrotic syndrome with characterized genetic mutations as a model to test the therapeutic potential of EVs derived from kidney progenitor cells (nKPCs).

METHODS

EVs were isolated from nKPCs derived from the urine of a preterm neonate. Three lines of urinary podocytes obtained from nephrotic patients' urine and a line of Alport syndrome patient podocytes were characterized and used to assess albumin permeability in response to nKPC-EVs or various drugs. RNA sequencing was conducted to identify commonly modulated pathways after nKPC-EV treatment. siRNA transfection was used to demonstrate the involvement of SUMO1 and SENP2 in the modulation of permeability.

RESULTS

Treatment with the nKPC-EVs significantly reduced permeability across all the steroid-resistant patients-derived and Alport syndrome-derived podocytes. At variance, podocytes appeared unresponsive to standard pharmacological treatments, with the exception of one line, in alignment with the patient's clinical response at 48 months. By RNA sequencing, only two genes were commonly upregulated in nKPC-EV-treated genetically altered podocytes: small ubiquitin-related modifier 1 (SUMO1) and Sentrin-specific protease 2 (SENP2). SUMO1 and SENP2 downregulation increased podocyte permeability confirming the role of the SUMOylation pathway.

CONCLUSIONS

nKPCs emerge as a promising non-invasive source of EVs with potential therapeutic effects on podocytes with genetic dysfunction, through modulation of SUMOylation, an important pathway for the stability of podocyte slit diaphragm proteins. Our findings also suggest the feasibility of developing a non-invasive in vitro model for screening regenerative compounds on patient-derived podocytes.

Rare heterozygous variants in paediatric steroid resistant nephrotic syndrome - a population-based analysis of their significance

Genetic testing in nephrotic syndrome may identify heterozygous predicted-pathogenic variants (HPPVs) in autosomal recessive (AR) genes that are known to cause disease in the homozygous or compound heterozygous state. In such cases, it can be difficult to define the variant's true significance and questions remain about whether a second pathogenic variant has been missed during analysis or whether the variant is an incidental finding. There are now known to be over 70 genes associated with nephrotic syndrome, the majority inherited as an AR trait. Knowledge of whether such HPPVs occur with equal frequency in patients compared to the general population would assist interpretation of their significance. Exome sequencing was performed on 187 Steroid-Resistant Nephrotic Syndrome (SRNS) paediatric patients recruited to a UK rare disease registry plus originating from clinics at Evelina, London. 59 AR podocytopathy linked genes were analysed in each patient and a list of HPPVs created. We compared the frequency of detected HPPVs with a 'control' population from the gnomAD database containing exome data from approximately 50,000 individuals. A bespoke filtering process was used for both patients and controls to predict 'likely pathogenicity' of variants. In total 130 Caucasian SRNS patients were screened across 59 AR genes and 201 rare heterozygous variants were identified. 17/201 (8.5%) were assigned as 'likely pathogenic' (HPPV) using our bespoke filtering method. Comparing each gene in turn, for SRNS patients with a confirmed genetic diagnosis, in 57 of the 59 genes we found no statistically significant difference in the frequency of these HPPVs between patients and controls (In genes ARHGDIA and TP53RK, we identified a significantly higher number of HPPVs in the control population compared with the patients when filtering was performed with 'high stringency' settings only). In the SRNS patients without a genetics diagnosis confirmed, there was no statistically significant difference identified in any gene between patient and control. In children with SRNS, we propose that identification of HPPV in AR podocytopathy linked genes is not necessarily representative of pathogenicity, given that the frequency is similar to that seen in controls for the majority. Whilst this may not exclude the presence of genetic kidney disease, this type of heterozygous variant is unlikely to be causal and each result must be interpreted in its clinical context.

Clinical Course of Nonresponders With Recurrent Focal Segmental Glomerulosclerosis After Pediatric Kidney Transplantation: A Retrospective Multicenter Study

BACKGROUND

Primary focal segmental glomerulosclerosis (FSGS) frequently recurs after kidney transplantation and is associated with poor graft survival. Patients who do not achieve remission (nonresponders) have an especially poor graft survival. However, the characteristics that may affect graft survival in nonresponders are unknown. This study aimed to determine the clinical characteristics associated with graft survival in nonresponders.

METHODS

We retrospectively collected the clinical records of patients with FSGS and an age at onset <16 years who experienced posttransplant recurrence of FSGS at six hospitals in Japan from 1993 to 2018.

RESULTS

Eight nonresponders with recurrent FSGS were enrolled in this study. The median time to recurrence after kidney transplantation was 1 day (interquartile range, 1-2 days). All patients received therapeutic plasma exchange and methylprednisolone pulse therapy. Rituximab was used as an add-on therapy in three patients. Five patients lost their graft within 2 years after kidney transplantation (rapid group). In contrast, three patients had much longer graft survival (nonrapid group). We compared the clinical characteristics of the rapid and nonrapid groups. Proteinuria tended to be lower in the nonrapid group at the third and subsequent months of therapy. The rapid group had persistent nephrotic syndrome. The rate of reduction in proteinuria was lower in the rapid group than in the nonrapid group.

CONCLUSIONS

Our study suggests that persistent nephrotic syndrome and a low rate of reduction in proteinuria may predict rapid progression to graft failure in nonresponders.

Novel mutation patterns in children with steroid-resistant nephrotic syndrome

Background

Idiopathic nephrotic syndrome (NS) in children poses treatment challenges, with a subset developing steroid-resistant nephrotic syndrome (SRNS). Genetic factors play a role, yet data on paediatric SRNS genetics in India are scarce. We conducted a prospective study using whole-exome sequencing to explore genetic variants and their clinical correlations.

Methods

A single-centre prospective study (October 2018-April 2023) enrolled children with SRNS, undergoing renal biopsy and genetic testing per institutional protocol. Clinical, histological, and genetic data were recorded. DNA isolation and next-generation sequencing were conducted for genetic analysis. Data collection included demographics, clinical parameters, and kidney biopsy findings. Syndromic features were evaluated, with second-line immunosuppressive therapy administered. Patient and renal outcomes are presented for patients with and without genetic variants.

Results

A total of 680 paediatric NS patients were analysed, with 121 (17.8%) having SRNS and 96 consent to genetic analysis. 69 (71.9%) had early SRNS, 27 (28.1%) late. Among participants, 62 (64.58%) had reportable genetic variants. The most common were in COL4A genes, with 20 (31.7%) positive. Renal biopsy showed focal segmental glomerulosclerosis in 31/42 (74%) with variants, 16/28 (57.1%) without variants. Second-line immunosuppressions varied, with CNIs the most common. Outcomes varied, with partial or complete remission achieved in some while others progressed to ESRD.

Conclusion

The study underscores the importance of genetic analysis in paediatric SRNS, revealing variants in 65.7% of cases. COL4A variants were predominant. Variants correlated with varied renal outcomes, highlighting potential prognostic implications. These findings emphasize the value of personalized approaches and further research in managing paediatric SRNS.