Proteomic Analysis of Idiopathic Nephrotic Syndrome Triggered by Primary Podocytopathies in Adults: Regulatory Mechanisms and Diagnostic Implications.

Idiopathic nephrotic syndrome (NS) is a heterogeneous group of glomerular disorders which includes two major phenotypes: minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS). MCD and FSGS are classic types of primary podocytopathies. We aimed to explore the molecular mechanisms in NS triggered by primary podocytopathies and evaluate diagnostic value of the selected proteomic signatures by analyzing blood proteome profiling. Totally, we recruited 90 participants in two cohorts. The first cohort was analyzed using label-free quantitative (LFQ) proteomics to discover differential expressed proteins and identify enriched biological process in NS which were further studied in relation to clinical markers of kidney injury. The second cohort was analyzed using parallel reaction monitoring-based quantitative proteomics to verify the data of LFQ proteomics and assess the diagnostic performance of the selected proteins using receiver-operating characteristic curve analysis. Several biological processes (such as immune response, cell adhesion, and response to hypoxia) were found to be associated with kidney injury during MCD and FSGS. Moreover, three proteins (CSF1, APOC3, and LDLR) had over 90% sensitivity and specificity in detecting adult NS triggered by primary podocytopathies. The identified biological processes may play a crucial role in MCD and FSGS pathogenesis. The three blood protein markers are promising for diagnosing adult NS triggered by primary podocytopathies.

Cerebral Venous Sinus Thrombosis as an Initial Presentation of Nephrotic Syndrome: A Case Report.

Cerebral sinovenous thrombosis (CSVT) encompasses a spectrum of disorders involving thrombosis of the cerebral venous system. As shown by previous epidemiological studies, the prevalence of cerebral sinovenous thrombosis is 4-7 cases per million people. Nephrotic syndrome was very rarely associated with thrombosis cerebral veins or sinuses. Hypercoagulability and thrombotic complications in nephrotic syndrome are most commonly seen in deep veins of the lower extremities and renal veins. Our case highlights a unique scenario in which cerebral sinovenous thrombosis was the initial presentation of nephrotic syndrome in a patient that was not an important past medical or surgical problem. The patient was brought to the emergency department with severe headache, vomiting, altered mental status, and generalized body swelling. Laboratory results showed proteinuria, hypoalbuminemia and hyperlipidemia. Non-contrast brain CT demonstrated hemorrhagic venous infarct associated with vasogenic edema. A subsequent brain MR venogram demonstrated occlusion of superior sagittal and right transverse sinuses. She was managed with low molecular weight heparin and intervenous corticosteroids then shifted to rivaroxaban and oral steroids, respectively, which resulted in massive clinical improvement and resolution of thrombus.

A novel flow cytometry panel to identify prognostic markers for steroid-sensitive forms of idiopathic nephrotic syndrome in childhood.

Introduction: The clinical evolution of steroid-sensitive forms of pediatric idiopathic nephrotic syndrome (INS) is highly heterogeneous following the standard treatment with prednisone. To date, no prognostic marker has been identified to predict the severity of the disease course starting from the first episode. Methods: In this monocentric prospective cohort study we set up a reproducible and standardized flow cytometry panel using two sample tubes (one for B-cell and one for T-cell subsets) to extensively characterized the lymphocyte repertoire of INS pediatric patients. A total of 44 children with INS at disease onset were enrolled, sampled before and 3 months after standard induction therapy with prednisone and followed for 12 months to correctly classify their disease based on relapses. Age-matched controls with non immune-mediated renal diseases or with urological disorders were also enrolled. Demographical, clinical, laboratory and immunosuppressive treatment data were registered. Results: We found that children with INS at disease onset had significantly higher circulating levels of total CD19+ and specific B-cell subsets (transitional, mature-naïve, plasmablasts/plasmacells, CD19+CD27+, unswitched, switched and atypical memory B cells) and reduced circulating levels of Tregs, when compared to age-matched controls. Prednisone therapy restored most B- and T-cell alterations. When patients were subdivided based on disease relapse, relapsing patients had significantly more transitional, CD19+CD27+ memory and in particular unswitched memory B cells at disease onset, which were predictive of a higher risk of relapse in steroid-sensitive patients by logistic regression analysis, irrespective of age. In accordance, B-cell dysregulations resulted mainly associated with steroid-dependence when patients were stratified in different disease severity forms. Of note, Treg levels were reduced independently from the disease subgroup and were not completely normalized by prednisone treatment. Conclusion: We have set up a novel, reproducible, disease-specific flow cytometry panel that allows a comprehensive characterization of circulating lymphocytes. We found that, at disease onset, relapsing patients had significantly more transitional, CD19+CD27+ memory and unswitched memory B cells and those who are at higher risk of relapse had increased circulating levels of unswitched memory B cells, independently of age. This approach can allow prediction of clinical evolution, monitoring of immunosuppression and tailored treatment in different forms of INS.

Immunoglobulin G4-related disease presenting with nephrotic syndrome due to minimal change disease: a case report.

BACKGROUND: Immunoglobulin G4-related disease is an inflammatory disease affecting multiple organs including the kidney. Immunoglobulin G4-related kidney disease most commonly manifests as a tubulointerstitial nephritis and is associated with glomerular disease in a proportion of cases. Membranous nephropathy is the most frequent glomerular lesion. Herein, we report the first documented case of immunoglobulin G4-related disease presenting with nephrotic syndrome owing to minimal change disease. CASE PRESENTATION: A 67-year-old South Asian male presented to our service with systemic upset and leg swelling. He had heavy proteinuria (urine protein:creatinine ratio 1042 mg/mmol) and was hypoalbuminemic (17 g/L) and hypercholersterolemic (9.3 mmol/L), consistent with the nephrotic syndrome. His serum creatinine was 140 µmol/L, and he was hypocomplementemic (C3 0.59 g/L, C4 < 0.02 g/L) with raised immunoglobulin G4 subclass levels (5.29 g/L). Kidney biopsy demonstrated minimal change disease alongside a plasma-cell-rich tubulointerstitial nephritis with strong positive staining for immunoglobulin G4. A diagnosis of minimal change disease in the setting of immunoglobulin G4-related disease was made. He was commenced on oral prednisolone at 60 mg daily but suffered infectious complications, including necrotizing fasciitis within 3 weeks of starting treatment, ultimately resulting in his death 52 days after initial presentation. CONCLUSION: This case highlights the potential for immunoglobulin G4-related disease to be associated with a spectrum of glomerular pathologies including minimal change disease. It adds to the differential diagnosis of secondary causes of minimal change disease, and moreover, aids as an important reminder of the potential complications of high-dose steroids used in its treatment.

[Expansion of the genotypic and phenotypic spectrum and treatment of four children with Steroid-resistant nephrotic syndrome due to variants of TRPC6 gene].

OBJECTIVE: To summarize the clinical and genetic characteristics, treatment and prognosis of four children with Steroid-resistant nephrotic syndrome (SRNS) due to variants of TRPC6 gene. METHODS: Clinical data of four children with SRNS admitted to Children's Hospital Affiliated to Zhengzhou University between May 2020 and August 2022 were collected. Peripheral blood samples were collected from the children and their parents, and whole exome sequencing was carried out. Sanger sequencing was used to verify the pathogenicity of the candidate variants among the children and their parents. RESULTS: All of the four children were found to harbor heterozygous variants of the TRPC6 gene, including c.523C>T (p.R175W), c.1327T>A (p.F443I), c.430G>C (p.E144Q) (unreported previously), and c.523C>T (p.R175W), which were all missense variants. Two of the children have shown a simple type, whilst two have shown a nephritis type, none had extrarenal phenotype. Comprehensive renal pathology of three children revealed focal segmental glomerulosclerosis (FSGS). Two children were treated with steroids combined with calcineurin inhibitors (CNIs), among whom one showed significant improvement in symptoms. CONCLUSION: Discoveries of the novel c.430G>C variant and the new SRNS phenotype of the c.1327T>A variant have expanded the mutational and phenotypic spectrum of the TRPC6 gene, which has provided a reference for clinical diagnosis and genetic counseling for the families.

Percutaneous kidney biopsies in children: a 24-year review in a tertiary center in northern Portugal.

INTRODUCTION: Percutaneous kidney biopsy (KB) is crucial to the diagnosis and management of several renal pathologies. National data on native KB in pediatric patients are scarce. We aimed to review the demographic and clinical characteristics and histopathological patterns in children who underwent native percutaneous KB over 24 years. METHODS: Retrospective observational study of patients undergoing native percutaneous KB in a pediatric nephrology unit between 1998 and 2021, comparing 3 periods: period 1 (1998-2005), period 2 (2006-2013), and period 3 (2014-2021). RESULTS: We found that 228 KB were performed, 78 (34.2%) in period 1, 91 (39.9%) in period 2, and 59 (25.9%) in period 3. The median age at KB was 11 (7-14) years. The main indications for KB were nephrotic syndrome (NS) (42.9%), hematuria and/or non-nephrotic proteinuria (35.5%), and acute kidney injury (13.2%). Primary glomerulopathies were more frequent (67.1%), particularly minimal change disease (MCD) (25.4%), IgA nephropathy (12.7%), and mesangioproliferative glomerulonephritis (GN) (8.8%). Of the secondary glomerulopathies, lupus nephritis (LN) was the most prevalent (11.8%). In group 1, hematuria and/or non-nephrotic proteinuria were the main reasons for KB, as opposed to NS in groups 2 and 3 (p < 0.01). LN showed an increasing trend (period 1-3: 2.6%-5.3%) and focal segmental glomerular sclerosis (FSGS) showed a slight decreasing trend (period 1-3: 3.1%-1.8%), without statistical significance. CONCLUSIONS: The main indication for KB was NS, which increased over time, justifying the finding of MCD as main histological diagnosis. LN showed an increase in incidence over time, while FSGS cases did not increase.

A case report of youth-onset lipoprotein glomerulopathy with APOE Chicago mutation.

BACKGROUND: This article reports an extremely rare case of lipoprotein glomerulopathy (LPG) with apolipoprotein E gene (APOE) Chicago mutation in a young Chinese male. Only five cases or families with APOE Chicago mutations have been reported in the literature. CASE PRESENTATION: The young male patient is manifested with nephrotic syndrome, accompanied by hyperlipidemia with a preferable increase in triglycerides and elevated ApoE level. Renal biopsy of the patient showed highly dilated glomerular capillaries filled with vacuolar lipids, segmentally fused podocyte foot processes, vacuolar degeneration of renal tubular epithelial cells and absence of electron-dense material, which indicates the diagnosis of LPG. Whole-exome gene sequencing identified the heterozygous mutation of NM_000041.4:c.494G > C (p.Arg165Pro), which is in the exon 4 of the APOE gene and also known as APOE Chicago mutation, a rare mutation of LPG. Further family pedigree gene analysis clarified that the mutation was inherited from the patient's mother, who does not have high ApoE levels or renal manifestations. This is also consistent with the incomplete penetrance of APOE gene mutations in LPG. Under lipid-lowering treatments, including a low-fat diet and fenofibrate, the patient's urinary protein was partially controlled, and the albumin level was recovered. CONCLUSION: Patients with nephrotic syndrome and elevated ApoE levels should be prompted into renal biopsy to avoid delay of appropriate treatment and unnecessary use of glucocorticoids. This case of LPG was diagnosed by renal biopsy and further verified with genetic sequencing. The timely diagnosis and treatment improved the patient's symptoms. This case is one of only six reported LPG cases or families with APOE Chicago mutation in the world.

Preference for anti-phospholipase A2 receptor antibody assay in patients with suspected membranous nephropathy: a survey study on medical practice after publication of Japanese Guidelines for Nephrotic Syndrome 2020.

BACKGROUND: International practice guidelines advocate for the use of anti-phospholipase A2 receptor (PLA2R) antibody testing to diagnose primary membranous nephropathy (pMN). This study aimed to clarify the current status of anti-PLA2R antibody testing in the diagnosis of pMN in Japan and to scrutinize the factors associated with the implementation of this antibody test. METHODS: Utilizing a web-based questionnaire for nephrologists, responses were collected from 306 facilities and 427 nephrologists between November 2021 and December 2021. Preference for anti-PLA2R antibody testing was also investigated. Factors related to the experience of quantifying anti-PLA2R antibodies were estimated by generalized estimating equations using a robust analysis of variance with clusters of facilities of affiliation. RESULTS: Of the 427 respondents, 140 (32.8%) had previous measurement experience at their current workplace and 165 (38.6%) had previous measurement experience overall. In pMN-suspected cases without contraindications to renal biopsy, 147 (34.4%) of the respondents opted to request anti-PLA2R antibody testing. The respondents' experience with anti-PLA2R antibody quantification at their current place of work was generally higher in university hospitals and increased with the annual number of kidney biopsies and the number of years since graduation. CONCLUSION: The results of this study suggest that a significant proportion of nephrologists in Japan have no experience in performing anti-PLA2R antibody assays, and that the assays may be hampered by the limited capabilities of the current workplace and the financial burden on facilities and patients.

Hypothyroidism among children and adolescents with nephrotic syndrome in Mulago National Referral Hospital, Kampala, Uganda; a cross-sectional study.

BACKGROUND: Nephrotic syndrome (NS) is the commonest glomerular disease among children. It is characterized by heavy proteinuria and is a risk factor for hypothyroidism in the affected children. Hypothyroidism is of concern because it affects the physical and intellectual development of children and adolescents. This study sought to establish the prevalence and factors associated with hypothyroidism among children and adolescents with NS. METHODS: A cross-sectional design was used to study 70 children and adolescents aged 1-19 years diagnosed with nephrotic syndrome and being followed up in the kidney clinic in Mulago National Referral Hospital. Questionnaires were used to collect patients' socio-demographics and clinical information. A blood sample was taken for analysis for thyroid stimulating hormone (TSH) and free thyroxine (FT4), renal function tests and serum albumin. Hypothyroidism included both overt and subclinical forms. Overt hypothyroidism was defined as TSH level > 10 mU/L and FT4 < 10pmol/L, or FT4 < 10pmol/l with normal TSH, or TSH < 0.5mU/l. Sub-clinical hypothyroidism was defined as TSH ranging between 5 and10 mU/L with normal age appropriate FT4 levels. Urine samples were collected and taken for a dipstick examination. The data was analyzed using STATA version 14. The Bayesian Logistic regression analysis approach was used to estimate odds ratios (OR) and their associated 95% credible intervals. All predictor variables with p value < 0.05 at frequentist statistical analysis were considered significant. RESULTS: The mean age (standard deviation) of participants was 9 years (3.8). There were more males; 36 of 70 (51.4%). The prevalence of hypothyroidism was 23% (16/70 participants). Of the 16 children with hypothyroidism, 3 (18.7%) had overt hypothyroidism while 13 had subclinical hypothyroidism. Only low serum albumin was found to be strongly associated with hypothyroidism; Bayesian OR 132.57 (CI 9.13-567.10) with a frequentist OR of 37 and a p value of 0.001. CONCLUSION: The prevalence of hypothyroidism among children and adolescent with nephrotic syndrome attending Mulago Hospital paediatric kidney clinic was 23%. Hypoalbuminemia was found to be associated with hypothyroidism. Therefore, children and adolescents that have severely low levels of serum albumin should be screened for hypothyroidism and linked to endocrinologists for care.

Fractional excretion of total protein in patients with nephrotic syndrome.

BACKGROUND: The urine protein to creatinine ratio (UPCR) correlates well with the 24-h urine protein test (24-h UPT) and is a reliable indicator of proteinuria. However, in nephrotic syndrome, the correlation between the UPCR and the 24-h UPT tends to decrease. To address this, we introduced the fractional excretion of total protein (FETP), which reflects serum total protein and creatinine levels because severe hypoproteinemia and/or elevated serum creatinine levels tend to occur under these conditions. The 24-h UPT corrected for body surface area (BSA) (24-h UPT/BSA) was used to take body size into consideration. The correlation coefficients for 24-h UPT/BSA and FETP and 24-h UPT/BSA and UPCR were calculated. The statistical significance of the differences between these coefficients was also calculated. METHODS: Thirty-six pediatric patients with nephrotic syndrome were included in this study. The FETP was calculated as total protein clearance/creatinine clearance (%). Correlation coefficients were calculated for 24-h UPT/BSA and FETP and 24-h UPT/BSA and UPCR. The statistical significance of the differences between these coefficients was also calculated. RESULTS: The mean ± standard error of FETP was 0.11% ± 0.013%. The correlation coefficients of FETP and UPCR with 24-h UPT/BSA were 0.91 and 0.81, respectively. The FETP demonstrated a significantly stronger correlation with 24-h UPT/BSA than with UPCR (p = 0.01). CONCLUSIONS: The FETP correlated more strongly with 24-h UPT/BSA than with UPCR in patients with nephrotic syndrome. The FETP is a reliable indicator of proteinuria in nephrotic syndrome, especially in patients with severe hypoproteinemia or elevated serum creatinine levels.

Two successful pregnancies in a membranous nephropathy patient: Case report and literature review.

BACKGROUND: Pregnancy in patients with nephrotic syndrome presents enormous challenges to both the mother and fetus, and there are no treatment guidelines for these patients. METHODS: We show a case of a woman with anti-PLA2R antibody-positive membranous nephropathy who did not have a kidney biopsy. Her clinical course during both pregnancies was closely followed and her medications were guided. RESULTS: She gave birth to 2 healthy babies and her condition was very well controlled with the help of medication. CONCLUSION: Patients with nephrotic syndrome can have successful pregnancies after drug treatment. In addition, similar to the non-pregnant population, percutaneous kidney biopsy is not required for the diagnosis of idiopathic membranous nephropathy (IMN) in pregnant nephrotic syndrome patients with anti-PLA2R antibody positive, but the etiology of secondary MN should be excluded.

Rationale and design of the Japanese Biomarkers in Nephrotic Syndrome (J-MARINE) study.

INTRODUCTION: Disease subtyping and monitoring are essential for the management of nephrotic syndrome (NS). Although various biomarkers for NS have been reported, their clinical efficacy has not been comprehensively validated in adult Japanese patients. METHODS: The Japanese Biomarkers in Nephrotic Syndrome (J-MARINE) study is a nationwide, multicenter, and prospective cohort study in Japan, enrolling adult (≥18 years) patients with minimal change disease (MCD), focal segmental glomerulosclerosis (FSGS), membranous nephropathy (MN), membranoproliferative glomerulonephritis (MPGN), C3 glomerulopathy (C3G), and lupus nephritis (LN). Baseline clinical information and plasma and urine samples will be collected at the time of immunosuppressive therapy initiation or biopsy. Follow-up data and plasma and urine samples will be collected longitudinally based on the designated protocols. Candidate biomarkers will be measured: CD80, cytotoxic T-lymphocyte antigen 4, and soluble urokinase plasminogen activator receptor for MCD and FSGS; anti-phospholipase A2 receptor and thrombospondin type-1 domain-containing protein 7A antibodies for MN; fragment Ba, C3a, factor I, and properdin for MPGN/C3G; and CD11b, CD16b, and CD163 for LN. Outcomes include complete and partial remission, relapse of proteinuria, a 30% reduction in estimated glomerular filtration rate (eGFR), eGFR decline, and initiation of renal replacement therapy. The diagnostic accuracy and predictive ability for clinical outcomes will be assessed for each biomarker. RESULTS: From April 2019 to April 2023, 365 patients were enrolled: 145, 21, 138, 10, and 51 cases of MCD, FSGS, MN, MPGN/C3G, and LN, respectively. CONCLUSION: This study will provide valuable insights into biomarkers for NS and serve as a biorepository for future studies.

Podocyte-specific Nup160 knockout mice develop nephrotic syndrome and glomerulosclerosis.

More than 60 monogenic genes mutated in steroid-resistant nephrotic syndrome (SRNS) have been identified. Our previous study found that mutations in nucleoporin 160 kD (NUP160) are implicated in SRNS. The NUP160 gene encodes a component of the nuclear pore complex. Recently, two siblings with homozygous NUP160 mutations presented with SRNS and a nervous system disorder. However, replication of nephrotic syndrome (NS)-associated phenotypes in a mammalian model following loss of Nup160 is needed to prove that NUP160 mutations cause SRNS. Here, we generated a podocyte-specific Nup160 knockout (Nup160podKO) mouse model using CRISPR/Cas9 and Cre/loxP technologies. We investigated NS-associated phenotypes in these Nup160podKO mice. We verified efficient abrogation of Nup160 in Nup160podKO mice at both the DNA and protein levels. We showed that Nup160podKO mice develop typical signs of NS. Nup160podKO mice exhibited progression of proteinuria to average albumin/creatinine ratio (ACR) levels of 15.06 ± 2.71 mg/mg at 26 weeks, and had lower serum albumin levels of 13.13 ± 1.34 g/l at 30 weeks. Littermate control mice had urinary ACR mean values of 0.03 mg/mg and serum albumin values of 22.89 ± 0.34 g/l at the corresponding ages. Further, Nup160podKO mice exhibited glomerulosclerosis compared with littermate control mice. Podocyte-specific Nup160 knockout in mice led to NS and glomerulosclerosis. Thus, our findings strongly support that mutations in NUP160 cause SRNS. The newly generated Nup160podKO mice are a reliable mammalian model for future study of the pathogenesis of NUP160-associated SRNS.

Neonatal nephrotic syndrome: all is not gloomy.

Congenital nephrotic syndrome (CNS) is a rare clinical syndrome with a constellation of proteinuria, hypoalbuminaemia and oedema, presenting within 3 months of birth. We present a rare case of neonatal nephrotic syndrome with a probable sepsis induced aetiology. The neonate was referred at day of life 15 with Klebsiella pneumonia sepsis and anasarca. On investigation, the patient had nephrotic range proteinuria, hypoalbuminaemia, generalised anasarca and ascites. The neonate was started on broad-spectrum antibiotics and furosemide. Genetic and other secondary causes of CNS were ruled out. With supportive management and resolution of sepsis, the neonate improved. This case highlights the rare cause of sepsis-induced nephrotic syndrome (NS), which required only supportive treatment without the need for aggressive management of CNS.

Rationale and design of the Nephrotic Syndrome Study Network (NEPTUNE) Match in glomerular diseases: designing the right trial for the right patient, today.

Glomerular diseases are classified using a descriptive taxonomy that is not reflective of the heterogeneous underlying molecular drivers. This limits not only diagnostic and therapeutic patient management, but also impacts clinical trials evaluating targeted interventions. The Nephrotic Syndrome Study Network (NEPTUNE) is poised to address these challenges. The study has enrolled >850 pediatric and adult patients with proteinuric glomerular diseases who have contributed to deep clinical, histologic, genetic, and molecular profiles linked to long-term outcomes. The NEPTUNE Knowledge Network, comprising combined, multiscalar data sets, captures each participant's molecular disease processes at the time of kidney biopsy. In this editorial, we describe the design and implementation of NEPTUNE Match, which bridges a basic science discovery pipeline with targeted clinical trials. Noninvasive biomarkers have been developed for real-time pathway analyses. A Molecular Nephrology Board reviews the pathway maps together with clinical, laboratory, and histopathologic data assembled for each patient to compile a Match report that estimates the fit between the specific molecular disease pathway(s) identified in an individual patient and proposed clinical trials. The NEPTUNE Match report is communicated using established protocols to the patient and the attending nephrologist for use in their selection of available clinical trials. NEPTUNE Match represents the first application of precision medicine in nephrology with the aim of developing targeted therapies and providing the right medication for each patient with primary glomerular disease.

New insights from the genetic work-up in early onset nephrotic syndrome: report from a registry in western India.

BACKGROUND: Eighty-five percent of infants with congenital nephrotic syndrome (CNS) and 66% with infantile NS (INS) are likely to have a monogenic etiology. There exists a significant genetic variability between different regions and ethnic groups. This study aimed to determine the genetic defects in children with CNS and INS by establishing a registry in western India. METHODS: In this cross-sectional study, pediatric nephrologists from 13 private and government institutions shared relevant clinical data and details of the genetic evaluation of children presenting with NS within the first year of life. RESULTS: The median age at presentation was 9 months (range 1-23, IQR 3-13 months), history of consanguinity between parents existed in 14 patients (34%), family history of similar illness in 6 (15%), and extra-renal manifestations in 17 (41%). Twenty-five (61%) were confirmed to have a monogenic etiology. NPHS1 gene was the most implicated (9/25) followed by PLCE1 (5/25). There were 12 variants of uncertain significance (VUS) involving 10 genes (10/25, 40%), and no definite genetic abnormality was found in 4 (25%). A re-analysis of these VUS attempted 2-3 years later facilitated reclassification of 7/12 (58%); increasing the diagnostic yield from 61 to 68.2%. CONCLUSIONS: Consistent with worldwide data, variants in NPHS1 gene were the most common cause of NS in infancy; however, PLCE1 was implicated more frequently in our cohort. NUP93 and COL4A3 were reported in early onset NS for the first time. Reclassification of VUS should be attempted, if feasible, since it may lead to a useful revision of diagnosis.

Chronic thrombotic microangiopathy presenting as acute nephrotic syndrome in a patient with renal cancer receiving tyrosine kinase inhibitor therapy.

Thrombotic microangiopathy (TMA) is a rare but serious side effect of tyrosine kinase inhibitor (TKI) therapy. Previous case reports of renal TMA have usually occurred in the first few months of TKI initiation with only very few cases occurring within 2-3 years. We report a case of a patient who was referred to the Nephrology service for nephrotic syndrome and worsening renal function after 8 years of sunitinib therapy for metastatic clear cell carcinoma of the kidney. Renal biopsy showed chronic TMA without another secondary aetiology identified. With discontinuation of sunitinib and pharmacological optimisation of his hypertension, his renal function and proteinuria both significantly improved. No relapse or recurrence of disease activity was noted after a year of follow-up. This case highlights the importance of remaining vigilant for the development of renal TMA even after an extended duration of TKI therapy.

Loss of helicase C-terminal domain of SMARCAL1 protein associated with severe Schimke immuno-osseous dysplasia.

Schimke immuno-osseous dysplasia (SIOD) is a rare multi-system condition caused by biallelic loss-of-function mutations in the SMARCAL1 gene. This disorder is characterized by disproportionate growth failure, T-cell deficiency, and renal dysfunction. Pathogenic variants in the SMARCAL1 gene have been reported in only approximately half of SIOD-affected individuals. Among these alterations, nonsense and frameshift mutations generally lead to a severe phenotype with early onset. In this study, we identified novel mutations in an Iranian patient with SIOD. A 4-year-old girl with developmental delay and facial dysmorphism was referred to our center for molecular diagnosis. We applied whole-exome and Sanger sequencing for co-segregation analysis. Subsequently, bioinformatic analysis was performed to assess the pathogenic effects of the variants and their post-transcriptional effects. We discovered two novel mutations (c.2281delT and c.2283delA) in exon 15 of the SMARCAL1 gene, resulting in a truncated protein with a loss of 193 amino acids (p.S761Rfs*1). Variant effect predictors indicated that these variants are pathogenic, and multi-sequence alignments revealed high conservation of this region among different species. Given that our patient exhibited severe a phenotype and passed away soon after receiving a definitive molecular diagnosis, we propose that the loss of the helicase C-terminal domain in the deleted part of SMARCAL1 may lead to the severe form of SIOD. Besides, the combination of growth retardation and bone abnormalities also plays a crucial role in the early diagnosis of the disease.