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Background and Objectives: Steroid-resistant nephrotic syndrome overwhelmingly progresses to ESRD. More than 30 monogenic genes have been identified to cause steroid-resistant nephrotic syndrome. We previously detected causative mutations using targeted panel sequencing in 30% of patients with steroid-resistant nephrotic syndrome. Panel sequencing has a number of limitations when compared with whole exome sequencing. We employed whole exome sequencing to detect monogenic causes of steroid-resistant nephrotic syndrome in an international cohort of 300 families., Design, Setting, Participants, & Measurements: Three hundred thirty-five individuals with steroid-resistant nephrotic syndrome from 300 families were recruited from April of 1998 to June of 2016. Age of onset was restricted to <25 years of age. Exome data were evaluated for 33 known monogenic steroid-resistant nephrotic syndrome genes., Results: In 74 of 300 families (25%), we identified a causative mutation in one of 20 genes known to cause steroid-resistant nephrotic syndrome. In 11 families (3.7%), we detected a mutation in a gene that causes a phenocopy of steroid-resistant nephrotic syndrome. This is consistent with our previously published identification of mutations using a panel approach. We detected a causative mutation in a known steroid-resistant nephrotic syndrome gene in 38% of consanguineous families and in 13% of nonconsanguineous families, and 48% of children with congenital nephrotic syndrome. A total of 68 different mutations were detected in 20 of 33 steroid-resistant nephrotic syndrome genes. Fifteen of these mutations were novel. NPHS1 , PLCE1 , NPHS2 , and SMARCAL1 were the most common genes in which we detected a mutation. In another 28% of families, we detected mutations in one or more candidate genes for steroid-resistant nephrotic syndrome., Conclusions: Whole exome sequencing is a sensitive approach toward diagnosis of monogenic causes of steroid-resistant nephrotic syndrome. A molecular genetic diagnosis of steroid-resistant nephrotic syndrome may have important consequences for the management of treatment and kidney transplantation in steroid-resistant nephrotic syndrome., (Copyright © 2018 by the American Society of Nephrology.)

Background and Objectives: Mutations in podocyte genes are associated with steroid-resistant nephrotic syndrome (SRNS), mostly affecting younger age groups. To date, it is unclear whether these patients benefit from intensified immunosuppression with cyclosporine A (CsA). The aim of this study was to evaluate the influence of podocyte gene defects in congenital nephrotic syndrome (CNS) and pediatric SRNS on the efficacy of CsA therapy and preservation of renal function., Design, Settings, Participants, & Measurements: Genotyping was performed in 91 CNS/SRNS patients, irrespective of age at manifestation or response to CsA., Results: Mutations were identified in 52% of families (11 NPHS1, 17 NPHS2, 11 WT1, 1 LAMB2, 3 TRPC6). Sixty-eight percent of patients with nongenetic SRNS responded to CsA, most of them achieved complete remission. In contrast, none of the patients with genetic CNS/SRNS experienced a complete remission and only two (17%) achieved a partial response, both affected by a WT1 mutation. Preservation of renal function was significantly better in children with nongenetic disease after a mean follow-up time of 8.6 years (ESRD in 29% versus 71%)., Conclusions: The mutation detection rate in our population was high (52%). Most patients with genetic CNS/SRNS did not benefit from CsA with significantly lower response rates compared with nongenetic patients and showed rapid progression to end-stage renal failure. These data strongly support the idea not to expose CNS/SRNS patients with inherited defects related to podocyte function to intensified immunosuppression with CsA.

Background: The development of nephrotic syndrome (NS) after allogeneic hematopoietic stem cell transplantation (HS-CT) is a rare complication with few long-term outcome data., Patients: Clinical course and long-term outcome of three adult patients and one child with NS after HSCT (total number of transplants n = 533) are presented., Results: The median age at onset of NS was 35 years (range 15 - 56), occurring at a median of 17 months (range 11 - 21) after HSCT. Discontinuation of cyclosporine A (CSA) prior to onset of NS was a consistent feature and occurred a median of 6 months (range 2 - 10 months) prior to the development of NS. The histopathological lesion was membranous nephropathy (n = 3) and membranoproliferative glomerulonephritis Type 1 (n = 1). History of acute or concomitant clinically apparent chronic graft versus host disease (GVHD) was present in all cases except the pediatric patient who had abundant DR-activated cytotoxic T cells without evidence of viral reactivation. Long-term immunosuppression for 11 - 36 months with steroids (n = 1), combined steroids and CSA (n = 2) or CSA alone in steroid-refractory NS (n = 1) resulted in sustained remission of the NS in all patients (12 months - 8 years off immunosuppression)., Conclusion: NS after HSCT seems to be etiologically related to subclinical or overt chronic GVHD, which flares up after discontinuation of CSA. However, resumption of immunosuppression can reverse NS as well as GVHD and induce favorable sustained long-term remission.

Background: Growing evidence shows that steroid-sensitive nephrotic syndrome (SSNS) is the result of a primary T-cell disturbance and leads to secondary anatomical and functional, however, not to immunological glomerular changes. In addition, immunoglobulin abnormalities in SSNS indicate a role of B-cell involvement., Patients and Methods: We therefore analyzed T- and B-cell activation markers in children with SSNS at different stages of the disease including different treatment regimens by measuring the soluble IL-2 receptor (sCD25) and the soluble low-affinity IgE receptor (sCD23), respectively. Seventy-five patients with SSNS (median age 8.0, range 2.5 - 18 years) were studied, 33 in relapse (RL) including 21 patients relapsing during alternate-day steroids (RL-SD). Forty-two patients were studied in remission (RM; 14 off treatment and 28 on alternate-day steroids (RM-AD)) and 22 age-matched children served as controls., Results: Serum concentrations of sCD25 were increased in RL (113.6 +/- 19.5 micromol/l) compared to RM (79.8 +/- 8 micromol/l, p < 0.02) and controls (74.8 +/- 0.9 micromol/l, p < 0.02). Patients with RL-SD did not have elevated sCD25. In relapse, sCD25 was inversely correlated with age (R = -0.36, p < 0.04) and positively correlated with total IgG (R = 0.37, p < 0.04). Urinary excretion of sCD25 was also significantly elevated in RL of SSNS compared to RM and controls (71.2 +/- 11.9 micromol/g creatinine vs. 39.1 +/- 4.8 and 32.0 +/- 4.2 micromol/g, p < 0.05). Serum levels of sCD 23 were significantly elevated in RL (6.22 +/- 0.65 microg/l) compared to RM (3.1 +/- 0.83 microg/l, p < 0.02) and to controls (3.4 +/- 0.93 microg/l). The highest values, however, were found in RL-SD (7.8 +/- 1.7 microg/l) vs. untreated RL (p < 0.007) and RM-AD (p < 0.002). In untreated RL there was a significant correlation of sCD23 and total IgE (R = 0.67, p < 0.02) and in RL-SD with total IgG (R = 0.45, p < 0.05). sCD23 and sCD25 were not correlated with each other., Conclusion: These data document parallel abnormalities of both CD23-mediated B as well as CD25-mediated T-cell activation and suggest that SSNS is not solely a disorder of T-cell dysfunction.

Polymorphisms in the genes encoding the high-affinity IgE receptor, the interleukin 4 (IL4) receptor and IL13 can be associated with the development of asthma and allergy. Although several studies have described an association between atopy and idiopathic childhood nephrotic syndrome (NS), it is not clear whether this association is of a causal nature. Furthermore, it is not known whether these polymorphisms are associated with the clinical course of NS. A total of 84 children (52 male and 32 female; mean age 12.1 years) with NS were included in the present study. Of these, 78 could be classified as either atopic or non-atopic. Atopy was defined by elevated IgE levels (>100 k-units/l) and/or a positive history of atopy (33 of 78 patients). DNA was extracted from blood collected in EDTA tubes, and polymorphisms at positions 50 and 551 of the IL4 receptor, position 110 of IL13 and position 181 of the high-affinity IgE receptor were investigated by sequence-specific PCR or direct sequencing. Although we noted a strong tendency towards a higher allele frequency of polymorphisms in children with atopy and NS compared with children with NS but without atopy (IL4 50, 30% compared with 18%; IL4 551, 39% compared with 31%; IL13 110, 45% compared with 33%; IgE 181, 12% compared with 13%), these differences did not reach statistical significance. There were no differences in the frequency of polymorphisms between the different clinical courses of NS (frequent relapsers, steroid-dependent or steroid-resistant NS). We conclude that polymorphisms in the IL4 receptor, the high-affinity IgE receptor and IL13 do not seem to predict the clinical course of NS, despite the fact that serum IgE elevations are more frequent in patients with NS than in normal control subjects. The investigated polymorphisms may contribute to the IgE switch in patients with NS.

Development of steroid dependency represents a significant therapeutic challenge in steroid-sensitive nephrotic syndrome. Previous studies have shown conflicting results concerning the benefit of a 12-week treatment with cyclophosphamide (CPO), with 24%-67% of patients achieving long-term remission. We therefore analyzed the clinical response of 20 consecutive children with steroid-dependent nephrotic syndrome (SDNS) (12 male, median age at start of treatment 5.9 years, range 3.2-14.7 years) treated at our institution with CPO (2 mg/kg per day) for 12 weeks since 1989. Median duration of follow-up was 5.8 (range 1.1-9.25) years. Only 6 of 20 children (30%) showed a long-term remission of >2 years, while 14 of 20 (70%) developed relapses again. Of these, 12 patients (86%) again developed steroid dependency, requiring further alternative treatment. Our data show that a 12-week course of CPO leads to unfavorable results in the majority of patients with SDNS. We therefore conclude that there is a need for further optimization of therapy in SDNS.

Aim: Urinary transferrin loss is a typical feature in relapse of the idiopathic nephrotic syndrome, however, the impact on serum iron homeostasis and hematological parameters has not been studied systematically so far., Patients and Methods: Therefore, we investigated serum iron (Fe), erythropoietin (EPO), ferritin (FN), transferrin (TF), total iron-binding capacity (TEBK), transferrin saturation and the soluble transferrin receptor (sTFR) combined with hematological parameters (hemoglobin, MCV, MCH) in 42 children with relapsing, steroid-sensitive nephrotic syndrome (NS) in remission (RM, n = 26) and relapse (RL, n = 16), including 13 patients who were studied in both states. Thirty-three age-matched healthy children served as controls., Results: Fe, TEBK and TF were significantly reduced in RL compared to RM in cross-sectional as well as in paired studies while ferritin, hematological parameters and EPO levels remained unchanged. A significant increase, however, of the soluble transferrin-receptor could be demonstrated in cross-sectional analysis comparing RL to RM and healthy controls (3568+/-713 mg/ml vs 2625+/-576 vs 2646+/-697; p < 0.001 respectively) as well as in paired analysis of 13 patients in RL and RM (p < 0.001)., Conclusion: We conclude that transient transferrin and iron deficiency occurs in RL of INS but this seems to be counterbalanced by upregulation of the sTFR, a mechanism that might be important in preventing the development of iron deficiency anemia during the active nephrotic state.

Background and Objective: The treatment of frequently relapsing steroid-sensitive nephrotic syndrome in children with established immunosuppressive drugs (steroids, cyclophosphamide, cyclosporin A) sometimes presents problems because of the expected incidence of side effects. Stimulation of the immune system with the anthelminthic drug levamisole in this disease has been documented. Aim of this study was to assess in a prospective but uncontrolled series of observations its value and side effects., Patients and Methods: 25 patients (15 boys, ten girls; median age 10 [3.5-22] years) were given levamisole, 2 mg/kg/48 h. Before this treatment was started eight of the children/adolescents (32%) had frequent relapses and 17 (68%) had become steroid-dependent. Treatment was started during steroid-induced remission and continued for 3-24 (median 6) month, while steroids were discontinued after four weeks., Results: Relapse frequency per patient month was reduced from a mean of 0.5 (0.33-0.83) before to 0.31 (0-0.67) during levamisole administration (P < 0.001). In 12 patients (48%) no or considerably fewer relapses were observed. Patients with exclusively frequent relapses responded to levamisole better than those with steroid dependence (7/8 [87.5%] vs. 5/18 [27.7%], P = 0.01). Side effects were reversible leukopenia in two patients and nonspecific skin rash as well as epigastric pain in one patient., Conclusion: Levamisole is an efficacious addition or alternative, with a low incidence of side effects, in the treatment of frequently relapsing nephrotic syndrome, particularly so in yet steroid-dependent patients.