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Nephrotic syndrome (NS) is a severe glomerulopathy characterized by severe proteinuria, hypoproteinemia, hypoalbuminemia, hyperlipidemia and widespread edema. There’ve been over sixty genes identified to date that are responsible for the development, structural integrity and functioning of podocytes. Pathogenic nucleotide variants of these genes lead to the podocytopathy in steroid-resistant nephrotic syndrome in 30% of cases. Depending on the protein damaged, the severity of the course, the extrarenal manifestations as well as the therapeutic options may vary. The molecular genetic research has therefore resulted in the fore in recent decades when pediatric patients with steroid-resistant NS are diagnosed.

It is believed that IgA nephropathy (IgAN) in childhood is predominantly manifested by hematuria with episodes of macrohematuria and has a relatively favorable course. The purpose of this research was to analyze the frequency of the use of mycophenolate mofetil (MMF) in children with IgAN in the Nephrology Department of the National Medical Research Center for Children’s Health (Moscow, Russia) and to evaluate the results of treatment in terms of the severity of proteinuria and the presence of a decrease in renal function by glomerular filtration. Materials and methods used: to assess the clinical course, histological features and kidney function during therapy, Authors analyzed the results of 737 biopsies performed in 2018-2022. Results: 126 biopsy specimens with predominant IgA deposition and mesangial proliferation and/or crescents were identified, 20 of them were excluded from further analysis due to the clinical picture of IgA vasculitis. 17 (16% of the remaining 106) patients had nephrotic-level of proteinuria prior to the biopsy, 11 had a history of acute kidney injury and 9 had a persistent decrease in glomerular filtration renal function. Steroid therapy with prednisolone at a dose of 0.5 to 1 mg/kg was carried out in 21 children, 14 (66.7%; CI 45.4-84.1%) of them had relapse or resistance. MMF therapy was started in 16 (11 boys and 5 girls) patients, median age of the therapy initiation was 13.4 [7.9; 15.3] y/o, 6 had a decrease in glomerular filtration rate (GFR) in the range of 64 to 85 ml/min. Kidney biopsy specimens were ere scored according to the Oxford classification MEST-C criteria. During the follow-up period (median 27.6 [20.0; 49.4] months), 14 (88% CI; 66-98) of 16 achieved complete (10) or partial remission, 2 patients had proteinuria of more than 1 g/l. Of 56 patients (median age 13.3 [9.6; 14.9] months) with a follow-up period of more than 6 months, a decrease in GFR was recorded in 5 (31.3%; CI 12.5-55.5) patients on MMF therapy and 4 (22.2%; CI 7.5-44.3) patients who received only a course of steroids and a single one (4.5%; CI 0.3-18.5) who received ACE inhibitor only. Analysis of biopsy results showed an increased risk of reduced GFR in patients with tubular atrophy. Conclusion: MMF therapy may have limited efficacy for proteinuria in IgAN though it does not prevent the GFR decline.

Introduction. Nephrotic syndrome (NS) with an onset in the first year of life is one of the actual problems in pediatric nephrology due to the limited therapeutic options, the ineffectiveness of immunosuppressive therapy, and inevitable progression to chronic kidney disease (CKD). The basis of congenital NS (CNS) and infantile NS (INS) is a genetically determined pathology of podocytes. The timely verification of such pathology allows avoiding ineffective therapy and helps to predict outcomes. Aim. To determine CNS and INS’s clinical and molecular genetic characteristics in Russian children. Materials and methods. This study performed molecular genetic testing of 99 children with an early onset of NS. Results. In children with CNS and INS, the genetic cause of the disease was verified in 85%. Causative nucleotide variants prevailed in the NPHS1, NPHS2, WT1 genes. It became possible to identify the significant nucleotide variants for the Russian group of children. Children with NS at an early age turned out to be resistant to therapy with calcineurin inhibitors, which should be considered when choosing therapy tactics. Conclusion. We detected the genetic structure of congenital and infantile NS in the Russian Federation during the study. We analyzed the effectiveness of therapy with calcineurin inhibitors and the rate of CKD progression in this group.