Treatment of idiopathic nephrotic syndrome at onset: a comparison between 8- and 12-week regimens in everyday clinical practice.

BACKGROUND: Optimal steroid treatment at onset of idiopathic nephrotic syndrome is still debated. The aim of this study was to analyze the clinical outcome at 24 months of follow-up in patients admitted to our unit for the first episode of steroid-sensitive nephrotic syndrome comparing two different steroid regimens. METHODS: We collected data on patients treated from 1992 to 2007 with prednisone according to the International Study on Kidney Diseases in Children 8-week regimen and since 2008 according to the Arbeitsgemeinschaft fur Padiatrische Nephrologie 12-week regimen. The primary outcome was to evaluate cumulative prednisone dosage at 12 and 24 months of follow-up in the two groups. As secondary outcomes, we considered mean relapse rate per patient; number of children without relapses at 6, 12, and 24 months; and number of patients who developed frequent relapses and steroid-dependent disease. RESULTS: Data were collected on 127 patients. Sixty-one subjects received the 8-week regimen and 66 the 12-week regimen. The mean cumulative prednisone dose at 12 and 24 months was not different, and the rate of patients without relapses was lower at 6 and 12 months in patients treated with the 8-week course, while no difference was observed at 24 months. CONCLUSIONS: Despite the limitations of a retrospective study with limited follow-up, our data indicate that switching treatment from a shorter to a longer scheme did not improve the clinical outcome at 24 months of observation. A higher resolution version of the Graphical abstract is available as Supplementary information.

Results of the PROPINE randomized controlled study suggest tapering of prednisone treatment for relapses of steroid sensitive nephrotic syndrome is not necessary in children.

Corticosteroid-related toxicity in children with steroid-sensitive nephrotic syndrome is primarily related to the cumulative dose of prednisone. To optimize treatment of relapses, we conducted the PROPINE study, a multicentric, open-label, randomized, superiority trial. Seventy-eight relapsing children aged 3-17 years who had not received steroid-sparing medications during the previous 12 months were randomized to receive, from day five after remission, either 18 doses of 40 mg/m2 of prednisone on alternate days (short arm), or the same cumulative dose tapered over double the time (long arm). Patients were monitored with an ad-hoc smartphone application, allowing daily reporting. The primary outcome was the six-month relapse rate at which time, 23/40 and 16/38 patients had relapsed in the long and short arms, respectively (no significant difference). Additionally, 40/78 patients were also enrolled in a secondary crossover study and were allocated to the opposite arm. Altogether, at six months, the relapse rate was 32/40 and 28/40 in the long and short arms, respectively (no significant difference). A post-hoc analysis excluding 30 patients treated with low-dose prednisone maintenance therapy failed to show significant differences between the two arms. No differences in adverse events, blood pressure and weight gain were observed. Thus, our data do not support the prescription of prolonged tapering schedules for relapses of steroid-sensitive nephrotic syndrome in children.

Refining genotype-phenotype correlations in 304 patients with autosomal recessive polycystic kidney disease and PKHD1 gene variants.

Autosomal recessive polycystic kidney disease (ARPKD) is a severe disease of early childhood that is clinically characterized by fibrocystic changes of the kidneys and the liver. The main cause of ARPKD are variants in the PKHD1 gene encoding the large transmembrane protein fibrocystin. The mechanisms underlying the observed clinical heterogeneity in ARPKD remain incompletely understood, partly due to the fact that genotype-phenotype correlations have been limited to the association of biallelic null variants in PKHD1 with the most severe phenotypes. In this observational study we analyzed a deep clinical dataset of 304 patients with ARPKD from two independent cohorts and identified novel genotype-phenotype correlations during childhood and adolescence. Biallelic null variants frequently show severe courses. Additionally, our data suggest that the affected region in PKHD1 is important in determining the phenotype. Patients with two missense variants affecting amino acids 709-1837 of fibrocystin or a missense variant in this region and a null variant less frequently developed chronic kidney failure, and patients with missense variants affecting amino acids 1838-2624 showed better hepatic outcome. Variants affecting amino acids 2625-4074 of fibrocystin were associated with poorer hepatic outcome. Thus, our data expand the understanding of genotype-phenotype correlations in pediatric ARPKD patients and can lay the foundation for more precise and personalized counselling and treatment approaches.

The carboxy-terminus of the human ARPKD protein fibrocystin can control STAT3 signalling by regulating SRC-activation.

Autosomal recessive polycystic kidney disease (ARPKD) is mainly caused by variants in the PKHD1 gene, encoding fibrocystin (FC), a large transmembrane protein of incompletely understood cellular function. Here, we show that a C-terminal fragment of human FC can suppress a signalling module of the kinase SRC and signal transducer and activator of transcription 3 (STAT3). Consistently, we identified truncating genetic variants specifically affecting the cytoplasmic tail in ARPKD patients, found SRC and the cytoplasmic tail of fibrocystin in a joint dynamic protein complex and observed increased activation of both SRC and STAT3 in cyst-lining renal epithelial cells of ARPKD patients.

Urine-derived podocytes-lineage cells: A promising tool for precision medicine in Alport Syndrome.

Alport Syndrome (ATS) is a rare genetic disorder caused by collagen IV genes mutations, leading to glomerular basement membrane damage up to end-stage renal disease. Podocytes, the main component of the glomerular structure, are the only cells able to produce all the three collagens IV alpha chains associated with ATS and thus, they are key players in ATS pathogenesis. However, podocytes-targeted therapeutic strategies have been hampered by the difficulty of non-invasively isolating them and transcripts-based diagnostic approaches are complicated by the inaccessibility of other COL4 chains-expressing cells. We firstly isolated podocyte-lineage cells from ATS patients' urine samples, in a non-invasive way. RT-PCR analysis revealed COL4A3, COL4A4, and COL4A5 expression. Transcripts analysis on RNA extracted from patient's urine derived podocyte-lineage cells allowed defining the pathogenic role of intronic variants, namely one mutation in COL4A3 (c.3882+5G>A), three mutations in COL4A4 (c.1623+2T>A, c.3699_3706+1del, c.2545+143T>A), and one mutation in COL4A5 (c.3454+2T>C). Therefore, our cellular model represents a novel tool, essential to unequivocally prove the effect of spliceogenic intronic variants on transcripts expressed exclusively at a glomerular level. This process is a key step for providing the patient with a definite molecular diagnosis and with a proper recurrence risk. The established system also opens up the possibility of testing personalized therapeutic approaches on disease-relevant cells.

Alport syndrome: a unified classification of genetic disorders of collagen IV α345: a position paper of the Alport Syndrome Classification Working Group.

Mutations in the genes COL4A3, COL4A4, and COL4A5 affect the synthesis, assembly, deposition, or function of the collagen IV α345 molecule, the major collagenous constituent of the mature mammalian glomerular basement membrane. These mutations are associated with a spectrum of nephropathy, from microscopic hematuria to progressive renal disease leading to ESRD, and with extrarenal manifestations such as sensorineural deafness and ocular anomalies. The existing nomenclature for these conditions is confusing and can delay institution of appropriate nephroprotective therapy. Herein we propose a new classification of genetic disorders of the collagen IV α345 molecule with the goal of improving renal outcomes through regular monitoring and early treatment.

A randomized clinical trial indicates that levamisole increases the time to relapse in children with steroid-sensitive idiopathic nephrotic syndrome.

Levamisole has been considered the least toxic and least expensive steroid-sparing drug for preventing relapses of steroid-sensitive idiopathic nephrotic syndrome (SSINS). However, evidence for this is limited as previous randomized clinical trials were found to have methodological limitations. Therefore, we conducted an international multicenter, placebo-controlled, double-blind, randomized clinical trial to reassess its usefulness in prevention of relapses in children with SSINS. The efficacy and safety of one year of levamisole treatment in children with SSINS and frequent relapses were evaluated. The primary analysis cohort consisted of 99 patients from 6 countries. Between 100 days and 12 months after the start of study medication, the time to relapse (primary endpoint) was significantly increased in the levamisole compared to the placebo group (hazard ratio 0.22 [95% confidence interval 0.11-0.43]). Significantly, after 12 months of treatment, six percent of placebo patients versus 26 percent of levamisole patients were still in remission. During this period, the most frequent serious adverse event (four of 50 patients) possibly related to levamisole was asymptomatic moderate neutropenia, which was reversible spontaneously or after treatment discontinuation. Thus, in children with SSINS and frequent relapses, levamisole prolonged the time to relapse and also prevented recurrence during one year of treatment compared to prednisone alone. However, regular blood controls are necessary for safety issues.

Risk Factors for Early Dialysis Dependency in Autosomal Recessive Polycystic Kidney Disease.

OBJECTIVE: To identify prenatal, perinatal, and postnatal risk factors for dialysis within the first year of life in children with autosomal recessive polycystic kidney disease (ARPKD) as a basis for parental counseling after prenatal and perinatal diagnosis. STUDY DESIGN: A dataset comprising 385 patients from the ARegPKD international registry study was analyzed for potential risk markers for dialysis during the first year of life. RESULTS: Thirty-six out of 385 children (9.4%) commenced dialysis in the first year of life. According to multivariable Cox regression analysis, the presence of oligohydramnios or anhydramnios, prenatal kidney enlargement, a low Apgar score, and the need for postnatal breathing support were independently associated with an increased hazard ratio for requiring dialysis within the first year of life. The increased risk associated with Apgar score and perinatal assisted breathing was time-dependent and vanished after 5 and 8 months of life, respectively. The predicted probabilities for early dialysis varied from 1.5% (95% CI, 0.5%-4.1%) for patients with ARPKD with no prenatal sonographic abnormalities to 32.3% (95% CI, 22.2%-44.5%) in cases of documented oligohydramnios or anhydramnios, renal cysts, and enlarged kidneys. CONCLUSIONS: This study, which identified risk factors associated with onset of dialysis in ARPKD in the first year of life, may be helpful in prenatal parental counseling in cases of suspected ARPKD.

Rituximab in steroid-dependent or frequently relapsing idiopathic nephrotic syndrome.

The outcome of steroid-dependent or frequently relapsing nephrotic syndrome of minimal change disease (MCD), mesangial proliferative GN (MesGN), or FSGS may be poor and with major treatment toxicity. This academic, multicenter, off-on trial (ClinicalTrials.gov #NCT00981838) primarily evaluated the effects of rituximab therapy followed by immunosuppression withdrawal on disease recurrence in 10 children and 20 adults with MCD/MesGN (n=22) or FSGS who had suffered ≥2 recurrences over the previous year and were in steroid-induced remission for ≥1 month. Participants received one dose (n=28) or two doses of rituximab (375 mg/m(2) intravenously). At 1 year, all patients were in remission: 18 were treatment-free and 15 never relapsed. Compared with the year before rituximab treatment, total relapses decreased from 88 to 22 and the per-patient median number of relapses decreased from 2.5 (interquartile range [IQR], 2-4) to 0.5 (IQR, 0-1; P<0.001) during 1 year of follow-up. Reduction was significant across subgroups (children, adults, MCD/MesGN, and FSGS; P<0.01). After rituximab, the per-patient steroid maintenance median dose decreased from 0.27 mg/kg (IQR, 0.19-0.60) to 0 mg/kg (IQR, 0-0.23) (P<0.001), and the median cumulative dose to achieve relapse remission decreased from 19.5 mg/kg (IQR, 13.0-29.2) to 0.5 mg/kg (IQR, 0-9.4) (P<0.001). Furthermore, the mean estimated GFR increased from 111.3±25.7 to 121.8±29.2 ml/min per 1.73 m(2) (P=0.01), with the largest increases in children and in FSGS subgroups. The mean height z score slope stabilized in children (P<0.01). Treatment was well tolerated. Rituximab effectively and safely prevented recurrences and reduced the need for immunosuppression in steroid-dependent or frequently relapsing nephrotic syndrome, and halted disease-associated growth deficit in children.

Bone marrow transplantation in Schimke immuno-osseous dysplasia.

Schimke immuno-osseous dysplasia (SIOD, OMIM 242900) is a rare autosomal recessive multisystem childhood disorder characterized by short stature, renal failure, T-cell immunodeficiency, and hypersensitivity to genotoxic agents. SIOD is associated with biallelic mutations in SMARCAL1 (SWI/SNF-related matrix-associated actin-dependent regulator of chromatin, subfamily a-like 1), which encodes a DNA stress response enzyme with annealing helicase activity. Two features of SIOD causing much morbidity and mortality are bone marrow failure and T-cell deficiency with the consequent opportunistic infections. To address the safety and efficacy of bone marrow transplantation (BMT) in SIOD, we reviewed the outcomes of the only five SIOD patients known to us in whom bone marrow or hematopoietic stem cell transplantation has been attempted. We find that only one patient survived the transplantation procedure and that the existing indicators of a good prognosis for bone marrow transplantation were not predictive in this small cohort. Given these observations, we also discuss some considerations for the poor outcomes.

Rituximab in children with resistant idiopathic nephrotic syndrome.

Idiopathic nephrotic syndrome resistant to standard treatments remains a therapeutic dilemma in pediatric nephrology. To test whether the anti-CD20 monoclonal antibody rituximab may benefit these patients, we conducted an open-label, randomized, controlled trial in 31 children with idiopathic nephrotic syndrome unresponsive to the combination of calcineurin inhibitors and prednisone. All children continued prednisone and calcineurin inhibitors at the doses prescribed before enrollment, and one treatment group received two doses of rituximab (375 mg/m(2) intravenously) as add-on therapy. The mean age was 8 years (range, 2-16 years). Rituximab did not reduce proteinuria at 3 months (change, -12% [95% confidence interval, -73% to 110%]; P=0.77 in analysis of covariance model adjusted for baseline proteinuria). Additional adjustment for previous remission and interaction terms (treatment by baseline proteinuria and treatment by previous remission) did not change the results. In conclusion, these data do not support the addition of rituximab to prednisone and calcineurin inhibitors in children with resistant idiopathic nephrotic syndrome.

NUP85 as a Neurodevelopmental Gene: From Podocyte to Neuron.

Pathogenic gene variants encoding nuclear pore complex (NPC) proteins were previously implicated in the pathogenesis of steroid-resistant nephrotic syndrome (SRNS). The NUP85 gene, encoding nucleoporin, is related to a very rare form of SRNS with limited genotype-phenotype information. We identified an Italian boy affected with an SRNS associated with severe neurodevelopmental impairment characterized by microcephaly, axial hypotonia, lack of achievement of motor milestones, and refractory seizures with an associated hypsarrhythmic pattern on electroencephalography. Brain magnetic resonance imaging (MRI) showed hypoplasia of the corpus callosum and a simplified gyration of the cerebral cortex. Since the age of 3 years, the boy was followed up at our Pediatric Nephrology Department for an SRNS, with a focal segmental glomerulosclerosis at renal biopsy. The boy died 32 months after SRNS onset, and a Whole-Exome Sequencing analysis revealed a novel compound heterozygous variant in NUP85 (NM_024844.5): 611T>A (p.Val204Glu), c.1904T>G (p.Leu635Arg), inherited from the father and mother, respectively. We delineated the clinical phenotypes of NUP85-related disorders, reviewed the affected individuals so far reported in the literature, and overall expanded both the phenotypic and the molecular spectrum associated with this ultra-rare genetic condition. Our study suggests a potential occurrence of severe neurological phenotypes as part of the NUP85-related clinical spectrum and highlights an important involvement of nucleoporin in brain developmental processes and neurological function.

Eligibility criteria for pediatric patients who may benefit from anti SARS-CoV-2 monoclonal antibody therapy administration: an Italian inter-society consensus statement.

The fast diffusion of the SARS-CoV-2 pandemic have called for an equally rapid evolution of the therapeutic options.The Human recombinant monoclonal antibodies (mAbs) have recently been approved by the Food and Drug Administration (FDA) and by the Italian Medicines Agency (AIFA) in subjects aged ≥12 with SARS-CoV-2 infection and specific risk factors.Currently the indications are specific for the use of two different mAbs combination: Bamlanivimab+Etesevimab (produced by Eli Lilly) and Casirivimab+Imdevimab (produced by Regeneron).These drugs have shown favorable effects in adult patients in the initial phase of infection, whereas to date few data are available on their use in children.AIFA criteria derived from the existing literature which reports an increased risk of severe COVID-19 in children with comorbidities. However, the studies analyzing the determinants for progression to severe disease are mainly monocentric, with limited numbers and reporting mostly generic risk categories.Thus, the Italian Society of Pediatrics invited its affiliated Scientific Societies to produce a Consensus document based on the revision of the criteria proposed by AIFA in light of the most recent literature and experts' agreement.This Consensus tries to detail which patients actually have the risk to develop severe disease, analyzing the most common comorbidities in children, in order to detail the indications for mAbs administration and to guide the clinicians in identifying eligible patients.

Phenotypic Variability in Siblings With Autosomal Recessive Polycystic Kidney Disease.

Introduction: Autosomal recessive polycystic kidney disease (ARPKD) is a rare monogenic disorder characterized by early onset fibrocystic hepatorenal changes. Previous reports have documented pronounced phenotypic variability even among siblings in terms of patient survival. The underlying causes for this clinical variability are incompletely understood. Methods: We present the longitudinal clinical courses of 35 sibling pairs included in the ARPKD registry study ARegPKD, encompassing data on primary manifestation, prenatal and perinatal findings, genetic testing, and family history, including kidney function, liver involvement, and radiological findings. Results: We identified 70 siblings from 35 families with a median age of 0.7 (interquartile range 0.1-6.0) years at initial diagnosis and a median follow-up time of 3.5 (0.2-6.2) years. Data on PKHD1 variants were available for 37 patients from 21 families. There were 8 patients from 7 families who required kidney replacement therapy (KRT) during follow-up. For 44 patients from 26 families, antihypertensive therapy was documented. Furthermore, 37 patients from 24 families had signs of portal hypertension with 9 patients from 6 families having substantial hepatic complications. Interestingly, pronounced variability in the clinical course of functional kidney disease was documented in only 3 sibling pairs. In 17 of 20 families of our cohort of neonatal survivors, siblings had only minor differences of kidney function at a comparable age. Conclusion: In patients surviving the neonatal period, our longitudinal follow-up of 70 ARPKD siblings from 35 families revealed comparable clinical courses of kidney and liver diseases in most families. The data suggest a strong impact of the underlying genotype.

Guidelines for Genetic Testing and Management of Alport Syndrome.

Genetic testing for pathogenic COL4A3-5 variants is usually undertaken to investigate the cause of persistent hematuria, especially with a family history of hematuria or kidney function impairment. Alport syndrome experts now advocate genetic testing for persistent hematuria, even when a heterozygous pathogenic COL4A3 or COL4A4 is suspected, and cascade testing of their first-degree family members because of their risk of impaired kidney function. The experts recommend too that COL4A3 or COL4A4 heterozygotes do not act as kidney donors. Testing for variants in the COL4A3-COL4A5 genes should also be performed for persistent proteinuria and steroid-resistant nephrotic syndrome due to suspected inherited FSGS and for familial IgA glomerulonephritis and kidney failure of unknown cause.

Cobalamin C defect presenting as severe neonatal hyperammonemia.

UNLABELLED: Cobalamin C (Cbl-C) defect is the most common inborn error of cobalamin metabolism which causes a block in the pathway responsible for the synthesis of its two metabolically active forms methyl- and adenosylcobalamin. Cbl-C defect causes the accumulation of methylmalonic acid and homocysteine and decreased methionine synthesis. The clinical presentation of patients with early-onset Cbl-C defect, characterized by a multisystem disease with severe neurological, ocular, hematological, renal, gastrointestinal, cardiac, and pulmonary manifestations, differs considerably from what observed in the "classical" form of methylmalonic aciduria caused by defect of methylmalonyl-CoA mutase. This last condition is in most cases dominated in the neonatal period by a metabolic encephalopathy "intoxication type" with severe hyperammonemia and ketoacidosis. We report a Cbl-C defect patient presenting a neonatal encephalopathy with severe hyperammonemia and ketoacidosis who was successfully treated with peritoneal dialysis. CONCLUSION: To the best of our knowledge, there are no reported cases of Cbl-C defect showing an acute presentation resembling a classical methylmalonic aciduria. This observation enlarges the spectrum of inherited diseases to be considered in the differential diagnosis of neonatal hyperammonemia.

Case Report: Two Cases of Pediatric Thrombotic Thrombocytopenic Purpura Treated With Combined Therapy.

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy caused by a severely reduced activity of the von Willebrand factor-cleaving protease ADAMTS13. Over 95% of TTPs are acquired, due to autoantibody inhibitors. In children, acquired TTP is a very rare, life-threatening disease. To date, no consensus exists on the treatment strategy of pediatric TTP. We report the cases of two pediatric patients with a diagnosis of TTP, successfully treated with a combination of various therapeutic approaches. Although the patients complained of different sets of symptoms, laboratory data showed Coombs negative hemolytic anemia, renal impairment, and low platelet count in both cases. The diagnosis of acquired TTP was supported by the PLASMIC score and confirmed by the reduction of the ADAMTS13 activity and the presence of anti-ADAMTS13 antibodies. Intravenous immunoglobulin, corticosteroids, and plasma exchange (PEX) were performed without delay. As soon as available, caplacizumab was added to the therapy, with a prompt normalization of platelet count. Nevertheless, ADAMTS13 activity was persistently low, and anti-ADAMTS13 antibodies level was high; thus, a course of rituximab was administered, with persistent normalization of laboratory findings. No adverse events were observed during the treatment. In our experience, the combined use of PEX, caplacizumab, and immunosuppressive therapy during the acute phase of the disease is safe and may have a significant impact on the prognosis with successful clinical outcome and decrease in life-threatening events.

Early childhood height-adjusted total kidney volume as a risk marker of kidney survival in ARPKD.

Autosomal recessive polycystic kidney disease (ARPKD) is characterized by bilateral fibrocystic changes resulting in pronounced kidney enlargement. Impairment of kidney function is highly variable and widely available prognostic markers are urgently needed as a base for clinical decision-making and future clinical trials. In this observational study we analyzed the longitudinal development of sonographic kidney measurements in a cohort of 456 ARPKD patients from the international registry study ARegPKD. We furthermore evaluated correlations of sonomorphometric findings and functional kidney disease with the aim to describe the natural disease course and to identify potential prognostic markers. Kidney pole-to-pole (PTP) length and estimated total kidney volume (eTKV) increase with growth throughout childhood and adolescence despite individual variability. Height-adjusted PTP length decreases over time, but such a trend cannot be seen for height-adjusted eTKV (haeTKV) where we even observed a slight mean linear increase of 4.5 ml/m per year during childhood and adolescence for the overall cohort. Patients with two null PKHD1 variants had larger first documented haeTKV values than children with missense variants (median (IQR) haeTKV 793 (450-1098) ml/m in Null/null, 403 (260-538) ml/m in Null/mis, 230 (169-357) ml/m in Mis/mis). In the overall cohort, estimated glomerular filtration rate decreases with increasing haeTKV (median (IQR) haeTKV 210 (150-267) ml/m in CKD stage 1, 472 (266-880) ml/m in stage 5 without kidney replacement therapy). Strikingly, there is a clear correlation between haeTKV in the first eighteen months of life and kidney survival in childhood and adolescence with ten-year kidney survival rates ranging from 20% in patients of the highest to 94% in the lowest quartile. Early childhood haeTKV may become an easily obtainable prognostic marker of kidney disease in ARPKD, e.g. for the identification of patients for clinical studies.

Consensus statement on standards and guidelines for the molecular diagnostics of Alport syndrome: refining the ACMG criteria.

The recent Chandos House meeting of the Alport Variant Collaborative extended the indications for screening for pathogenic variants in the COL4A5, COL4A3 and COL4A4 genes beyond the classical Alport phenotype (haematuria, renal failure; family history of haematuria or renal failure) to include persistent proteinuria, steroid-resistant nephrotic syndrome, focal and segmental glomerulosclerosis (FSGS), familial IgA glomerulonephritis and end-stage kidney failure without an obvious cause. The meeting refined the ACMG criteria for variant assessment for the Alport genes (COL4A3-5). It identified 'mutational hotspots' (PM1) in the collagen IV α5, α3 and α4 chains including position 1 Glycine residues in the Gly-X-Y repeats in the intermediate collagenous domains; and Cysteine residues in the carboxy non-collagenous domain (PP3). It considered that 'well-established' functional assays (PS3, BS3) were still mainly research tools but sequencing and minigene assays were commonly used to confirm splicing variants. It was not possible to define the Minor Allele Frequency (MAF) threshold above which variants were considered Benign (BA1, BS1), because of the different modes of inheritances of Alport syndrome, and the occurrence of hypomorphic variants (often Glycine adjacent to a non-collagenous interruption) and local founder effects. Heterozygous COL4A3 and COL4A4 variants were common 'incidental' findings also present in normal reference databases. The recognition and interpretation of hypomorphic variants in the COL4A3-COL4A5 genes remains a challenge.

Time for initial response to steroids is a major prognostic factor in idiopathic nephrotic syndrome.

OBJECTIVE: To identify early prognostic factors for idiopathic nephrotic syndrome (INS) in childhood. STUDY DESIGN: A retrospective analysis of 103 patients with INS at onset, all treated in a single center with the same induction protocol, was conducted. Minimum length of follow-up was 2 years; median length of follow-up was 43 months. Survival data were assessed with Cox-Mantel analysis. Predictive values were estimated with receiver operating characteristic curves. RESULTS: The median time of response to steroid therapy was 7 days. A significant association was found between the interval from onset of steroid therapy to remission and the risk of relapsing within 3 months after steroid therapy discontinuation (P < .0001). A similar association was found between the time to achieve remission and the risk of developing frequent relapsing or steroid-dependent nephrotic syndrome (P < .0001), the prescription of maintenance steroid therapy (P < .003), and the prescription of all other non-steroid drugs (P < .0001) during follow-up. Patients with non-relapsing and infrequent relapsing nephrotic syndrome had a median time to achieve remission <7 days; in patients with frequent relapsing and steroid-dependent nephrotic syndrome, this median was >7 days. CONCLUSION: The interval from onset of steroid therapy to remission is an accurate early prognostic factor in INS.