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Blasco M, Quiroga B, García-Aznar JM, Castro-Alonso C, Fernández-Granados SJ, Luna E, Fernández Fresnedo G, Ossorio M, Izquierdo MJ, Sanchez-Ospina D, Castañeda-Infante L, Mouzo R, Cao M, Besada-Cerecedo ML, Pan-Lizcano R, Torra R, Ortiz A, de Sequera P. Genetic Characterization of Kidney Failure of Unknown Etiology in Spain: Findings From the GENSEN Study. Am J Kidney Dis 2024:S0272-6386(24)00844-8. [PMID: 38972501 DOI: 10.1053/j.ajkd.2024.04.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 04/17/2024] [Accepted: 04/30/2024] [Indexed: 07/09/2024]
Abstract
RATIONALE & OBJECTIVE Chronic kidney disease (CKD) of unknown etiology (CKDUE) is one of the main global causes of kidney failure. While genetic studies may identify an etiology in these patients, few studies have implemented genetic testing of CKDUE in population-based series of patients which was the focus of the GENSEN. STUDY DESIGN Case series. SETTINGS & PARTICIPANTS 818 patients aged ≤45 years at 51 Spanish centers with CKDUE, and either an estimated GFR <15 mL/min/1.73 m2 or treatment with maintenance dialysis or transplantation. OBSERVATIONS Genetic testing for 529 genes associated to inherited nephropathies using high-throughput sequencing (HTS). Pathogenic and/or likely pathogenic (P/LP) gene variants concordant with the inheritance pattern were detected in 203 (24.8%) patients. Variants in type IV collagen genes were the most frequent (COL4A5, COL4A4, COL4A3; 35% of total gene variants), followed by NPHP1, PAX2, UMOD, MUC1 and INF2 (7.3%, 5.9%, 2.5%, 2.5% and 2.5% respectively). Overall, 87 novel variants classified as P/LP were identified. The top 5 most common previously undiagnosed diseases were Alport syndrome spectrum (35% of total positive reports), genetic podocytopathies (19%), nephronophthisis (11%), autosomal dominant tubulointerstitial kidney disease (7%) and congenital anomalies of the kidney and urinary tract (CAKUT: 5%). Family history of kidney disease was reported by 191 (23.3 %) participants and by 65/203 (32.0%) patients with P/LP variants. LIMITATIONS Missing data. Selection bias resulting from voluntary enrollment. CONCLUSIONS Genomic testing with HTS identified a genetic cause of kidney disease in approximately one quarter of young patients with CKDUE and advanced kidney disease. These findings suggest that genetic studies are a potentially useful tool for the evaluation of people with CKDUE.
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Affiliation(s)
- Miquel Blasco
- Nephrology and Kidney Transplant Department. National Reference Center for Complex Glomerular Diseases (CSUR). Hospital Clínic, Barcelona University, Barcelona, Spain; Fundació de Recerca Clínic Barcelona-Institut d'Investigacions Biomèdiques August Pi i Sunyer (FRCB-IDIBAPS), Barcelona, Spain; RICORS2040, Madrid, Spain
| | - Borja Quiroga
- RICORS2040, Madrid, Spain; IIS-La Princesa. Servicio de Nefrología, Hospital Universitario de la Princesa, Madrid, Spain
| | - José M García-Aznar
- (H)ealthincode. Clinical Area of Genetic Diagnostic in Nephrology and Immunology, A Coruña, Spain
| | - Cristina Castro-Alonso
- Department of Nephrology. Doctor Peset University Hospital. Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunitat Valenciana (FISABIO) Valencia, Spain
| | - Saulo J Fernández-Granados
- Hospital Universitario Insular de Gran Canaria, Nephrology Service, Las Palmas de Gran Canaria, Las Palmas, Spain
| | - Enrique Luna
- Complejo Hospitalario Universitario de Badajoz, Unidad enfermedades genéticas renales, Servicio de Nefrologia. Badajoz, Spain
| | - Gema Fernández Fresnedo
- Nephrology Department,Hospital Marqués de Valdecilla-Grupo de Inmunopatología IDIVAL,Santander,Spain
| | - Marta Ossorio
- Nephrology Department, Hospital Universitario La Paz, Madrid, Spain
| | | | | | | | - Ricardo Mouzo
- Nephrology Department, Hospital El Bierzo, Ponferrada, Spain
| | - Mercedes Cao
- Nephrology Department, Complexo Hospitalario Universitario A Coruña, A Coruña, Spain
| | | | | | - Roser Torra
- RICORS2040, Madrid, Spain; Inherited kidney diseases, Nephrology Department, Fundació Puigvert. Institut de Recerca Sant Pau. Medicine Department, Universitat Autònoma de Barcelona (UAB). Spain
| | - Alberto Ortiz
- RICORS2040, Madrid, Spain; Nephrology and Hypertension Department, IIS-Fundación Jiménez Díaz UAM, Madrid, Spain; Medicine Department, Facultad de Medicina, Universidad Autónoma de Madrid, Madrid, Spain.
| | - Patricia de Sequera
- RICORS2040, Madrid, Spain; Nephrology Department,Hospital Universitario Infanta Leonor,Madrid,Spain; Universidad Complutense de Madrid,Madrid,Spain.
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Finn LS. Nephrotic Syndrome Throughout Childhood: Diagnosing Podocytopathies From the Womb to the Dorm. Pediatr Dev Pathol 2024:10935266241242669. [PMID: 38745407 DOI: 10.1177/10935266241242669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
The etiologies of podocyte dysfunction that lead to pediatric nephrotic syndrome (NS) are vast and vary with age at presentation. The discovery of numerous novel genetic podocytopathies and the evolution of diagnostic technologies has transformed the investigation of steroid-resistant NS while simultaneously promoting the replacement of traditional morphology-based disease classifications with a mechanistic approach. Podocytopathies associated with primary and secondary steroid-resistant NS manifest as diffuse mesangial sclerosis, minimal change disease, focal segmental glomerulosclerosis, and collapsing glomerulopathy. Molecular testing, once an ancillary option, has become a vital component of the clinical investigation and when paired with kidney biopsy findings, provides data that can optimize treatment and prognosis. This review focuses on the causes including selected monogenic defects, clinical phenotypes, histopathologic findings, and age-appropriate differential diagnoses of nephrotic syndrome in the pediatric population with an emphasis on podocytopathies.
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Affiliation(s)
- Laura S Finn
- Department of Pathology and Laboratory Medicine, Perelman School of Medicine at The University of Pennsylvania, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
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Goodman KN, Puapatanakul P, Barton KT, He M, Miner JH, Gaut JP. A Case of Congenital Nephrotic Syndrome with Crescents Caused by a Novel Compound Heterozygous Pairing of NPHS1 Genetic Variants. Case Rep Nephrol 2024; 2024:5121375. [PMID: 38444459 PMCID: PMC10914425 DOI: 10.1155/2024/5121375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 02/07/2024] [Accepted: 02/17/2024] [Indexed: 03/07/2024] Open
Abstract
Congenital nephrotic syndrome is an autosomal recessive inherited disorder that manifests as steroid-resistant massive proteinuria in the first three months of life. Defects in the glomerular filtration mechanism are the primary etiology. We present a child who developed severe nephrotic syndrome at two weeks of age and eventually required a bilateral nephrectomy. Genetic testing revealed compound heterozygous variants in NPHS1 including a known pathogenic variant and a missense variant of uncertain significance. Light microscopy revealed crescent formation-an atypical finding in congenital nephrotic syndrome caused by nephrin variants-in addition to focal segmental and global glomerulosclerosis. Electron microscopy showed diffuse podocyte foot process effacement. Confocal and Airyscan immunofluorescence microcopy showed aggregation of nephrin in the podocyte cell body that is not a result of diffuse podocyte foot process effacement as seen in minimal change disease. These findings confirm the novel variant as pathogenic.
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Affiliation(s)
- Kyle N. Goodman
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Pongpratch Puapatanakul
- Division of Nephrology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Kevin T. Barton
- Division of Nephrology, Hypertension and Apheresis, St. Louis Children's Hospital, St. Louis, MO, USA
| | - Mai He
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Jeffrey H. Miner
- Division of Nephrology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
| | - Joseph P. Gaut
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, MO, USA
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Keller MP, O’Connor C, Bitzer M, Schueler KL, Stapleton DS, Emfinger CH, Broman AT, Hodgin JB, Attie AD. Genetic Analysis of Obesity-Induced Diabetic Nephropathy in BTBR Mice. Diabetes 2024; 73:312-317. [PMID: 37935024 PMCID: PMC10796299 DOI: 10.2337/db23-0444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 10/24/2023] [Indexed: 11/09/2023]
Abstract
Diabetic nephropathy (DN) is the leading cause of end-stage renal disease in the U.S. and has a significant impact on human suffering. Leptin-deficient BTBR (BTBRob/ob) mice develop hallmark features of obesity-induced DN, whereas leptin-deficient C57BL/6J (B6ob/ob) mice do not. To identify genetic loci that underlie this strain difference, we constructed an F2 intercross between BTBRob/ob and B6ob/ob mice. We isolated kidneys from 460 F2 mice and histologically scored them for percent mesangial matrix and glomerular volume (∼50 glomeruli per mouse), yielding ∼45,000 distinct measures in total. The same histological measurements were made in kidneys from B6 and BTBR mice, either lean or obese (Lepob/ob), at 4 and 10 weeks of age, allowing us to assess the contribution of strain, age, and obesity to glomerular pathology. All F2 mice were genotyped for ∼5,000 single nucleotide polymorphisms (SNPs), ∼2,000 of which were polymorphic between B6 and BTBR, enabling us to identify a quantitative trait locus (QTL) on chromosome 7, with a peak at ∼30 Mbp, for percent mesangial matrix, glomerular volume, and mesangial volume. The podocyte-specific gene nephrin (Nphs1) is physically located at the QTL and contains high-impact SNPs in BTBR, including several missense variants within the extracellular immunoglobulin-like domains. ARTICLE HIGHLIGHTS
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Affiliation(s)
- Mark P. Keller
- Department of Biochemistry, University of Wisconsin–Madison
| | - Chris O’Connor
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | - Markus Bitzer
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI
| | | | | | | | - Aimee Teo Broman
- Department of Biostatistics and Medical Informatics, University of Wisconsin–Madison
| | | | - Alan D. Attie
- Department of Biochemistry, University of Wisconsin–Madison
- Department of Chemistry, University of Wisconsin–Madison, Madison, WI
- Department of Medicine, University of Wisconsin–Madison
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Ma S, Qiu Y, Zhang C. Cytoskeleton Rearrangement in Podocytopathies: An Update. Int J Mol Sci 2024; 25:647. [PMID: 38203817 PMCID: PMC10779434 DOI: 10.3390/ijms25010647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/14/2023] [Accepted: 01/01/2024] [Indexed: 01/12/2024] Open
Abstract
Podocyte injury can disrupt the glomerular filtration barrier (GFB), leading to podocytopathies that emphasize podocytes as the glomerulus's key organizer. The coordinated cytoskeleton is essential for supporting the elegant structure and complete functions of podocytes. Therefore, cytoskeleton rearrangement is closely related to the pathogenesis of podocytopathies. In podocytopathies, the rearrangement of the cytoskeleton refers to significant alterations in a string of slit diaphragm (SD) and focal adhesion proteins such as the signaling node nephrin, calcium influx via transient receptor potential channel 6 (TRPC6), and regulation of the Rho family, eventually leading to the disorganization of the original cytoskeletal architecture. Thus, it is imperative to focus on these proteins and signaling pathways to probe the cytoskeleton rearrangement in podocytopathies. In this review, we describe podocytopathies and the podocyte cytoskeleton, then discuss the molecular mechanisms involved in cytoskeleton rearrangement in podocytopathies and summarize the effects of currently existing drugs on regulating the podocyte cytoskeleton.
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Affiliation(s)
| | | | - Chun Zhang
- Department of Nephrology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China; (S.M.); (Y.Q.)
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Thomasová D, Zelinová M, Libik M, Geryk J, Votýpka P, Rajnochová Bloudíčková S, Krejčí K, Reiterová J, Jančová E, Machová J, Kollárová M, Rychík I, Havrda M, Horáčková M, Putzová M, Šafránek R, Kollár M, Macek M. The most common founder pathogenic variant c.868G > A (p.Val290Met) in the NPHS2 gene in a representative adult Czech cohort with focal segmental glomerulosclerosis is associated with a milder disease and its underdiagnosis in childhood. Front Med (Lausanne) 2023; 10:1320054. [PMID: 38170106 PMCID: PMC10759319 DOI: 10.3389/fmed.2023.1320054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 11/24/2023] [Indexed: 01/05/2024] Open
Abstract
Background Genetic focal segmental glomerulosclerosis (FSGS) is caused by pathogenic variants in a broad spectrum of genes that have a variable representation based on subjects' ethnicity and/or age. The most frequently mutated autosomal recessive gene in FSGS is NPHS2. In this study, we analyzed the spectrum of NPHS2 variants and their associated phenotype in Czech adult FSGS patients. Methods A representative cohort of 234 adult patients with FSGS, derived from 225 families originating from all regions of Czechia, was analyzed by massively parallel sequencing. In this study, we focused on the comprehensive analysis of the NPHS2 gene. The histological classification of FSGS followed the Columbia classification. Results We detected seven (3%) cases bearing homozygous or compound heterozygous pathogenic NPHS2 variants. A single pathogenic variant c.868G > A (p.Val290Met) was found in the majority of NPHS2-positive cases (86%; 6 out of 7) in histologically confirmed instances of FSGS. Its allele frequency among unrelated NPHS2-associated FSGS patients was 50% (6/12), and Haplotype analysis predicted its origin to be a result of a founder effect. There is an identical V290M-related haplotype on all V290M alleles spanning a 0,7 Mb region flanking NPHS2 in Central European FSGS populations. The phenotype of the p.Val290Met NPHS2-associated FSGS demonstrated a later onset and a much milder course of the disease compared to other NPHS2 pathogenic variants associated with FSGS. The mean age of the FSGS diagnosis based on kidney biopsy evaluation was 31.2 ± 7.46 years. In 50% of all cases, the initial disease manifestation of proteinuria occurred only in adulthood, with 83% of these cases not presenting with edemas. One-third (33%) of the studied subjects progressed to ESRD (2 out of 6) at the mean age of 35.0 ± 2.82 years. Conclusions We identified the most prevalent pathogenic variant, p.Val290Met, in the NPHS2 gene among Czech adult FSGS patients, which has arisen due to a founder effect in Central Europe. The documented milder course of the disease associated with this variant leads to the underdiagnosis in childhood. We established the histopathological features of the NPHS2-associated adult FSGS cases based on the Columbia classification. This might improve patient stratification and optimize their treatment.
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Affiliation(s)
- Dana Thomasová
- Institute of Biology and Medical Genetics, University Hospital Motol and 2nd Faculty of Medicine, Charles University Prague, Prague, Czechia
| | - Michaela Zelinová
- Institute of Biology and Medical Genetics, University Hospital Motol and 2nd Faculty of Medicine, Charles University Prague, Prague, Czechia
| | - Malgorzata Libik
- Institute of Biology and Medical Genetics, University Hospital Motol and 2nd Faculty of Medicine, Charles University Prague, Prague, Czechia
| | - Jan Geryk
- Institute of Biology and Medical Genetics, University Hospital Motol and 2nd Faculty of Medicine, Charles University Prague, Prague, Czechia
| | - Pavel Votýpka
- Institute of Biology and Medical Genetics, University Hospital Motol and 2nd Faculty of Medicine, Charles University Prague, Prague, Czechia
| | | | - Karel Krejčí
- 3rd Department of Internal Medicine-Nephrology, Rheumatology and Endocrinology, University Hospital and Faculty of Medicine Palacký University Olomouc, Olomouc, Czechia
| | - Jana Reiterová
- Department of Nephrology, General University Hospital in Prague, First Faculty of Medicine, Charles University, Prague, Czechia
| | - Eva Jančová
- Department of Nephrology, General University Hospital in Prague, First Faculty of Medicine, Charles University, Prague, Czechia
| | - Jana Machová
- Department of Internal Medicine I, Faculty of Medicine in Pilsen, Charles University and Teaching Hospital, Pilsen, Czechia
- Biomedical Centre, Faculty of Medicine in Pilsen, Charles University, Pilsen, Czechia
| | - Martina Kollárová
- Department of Internal Medicine, University Hospital Vinohrady and Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Ivan Rychík
- Department of Internal Medicine, University Hospital Vinohrady and Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Martin Havrda
- Department of Internal Medicine, University Hospital Vinohrady and Third Faculty of Medicine, Charles University, Prague, Czechia
| | - Miroslava Horáčková
- Department of Internal Medicine, University Hospital Motol and 2nd Faculty of Medicine, Charles University, Prague, Czechia
| | - Martina Putzová
- Biopticka Laboratory, Pilsen, Czechia
- Faculty of Medicine in Plzeň - Charles University, Pilsen, Czechia
| | - Roman Šafránek
- Department of Nephrology, University Hospital Hradec Králové, Faculty of Medicine in Hradec Králové, Charles University, Hradec Králové, Czechia
| | - Marek Kollár
- Department of Pathology, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Milan Macek
- Institute of Biology and Medical Genetics, University Hospital Motol and 2nd Faculty of Medicine, Charles University Prague, Prague, Czechia
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7
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Sambharia M, Rastogi P, Thomas CP. Monogenic focal segmental glomerulosclerosis: A conceptual framework for identification and management of a heterogeneous disease. AMERICAN JOURNAL OF MEDICAL GENETICS. PART C, SEMINARS IN MEDICAL GENETICS 2022; 190:377-398. [PMID: 35894442 PMCID: PMC9796580 DOI: 10.1002/ajmg.c.31990] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 05/31/2022] [Accepted: 06/30/2022] [Indexed: 01/29/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is not a disease, rather a pattern of histological injury occurring from a variety of causes. The exact pathogenesis has yet to be fully elucidated but is likely varied based on the type of injury and the primary target of that injury. However, the approach to treatment is often based on the degree of podocyte foot process effacement and clinical presentation without sufficient attention paid to etiology. In this regard, there are many monogenic causes of FSGS with variable presentation from nephrotic syndrome with histological features of primary podocytopathy to more modest degrees of proteinuria with limited evidence of podocyte foot process injury. It is likely that genetic causes are largely underdiagnosed, as the role and the timing of genetic testing in FSGS is not established and genetic counseling, testing options, and interpretation of genotype in the context of phenotype may be outside the scope of practice for both nephrologists and geneticists. Yet most clinicians believe that a genetic diagnosis can lead to targeted therapy, limit the use of high-dose corticosteroids as a therapeutic trial, and allow the prediction of the natural history and risk for recurrence in the transplanted kidney. In this manuscript, we emphasize that genetic FSGS is not monolithic in its presentation, opine on the importance of genetic testing and provide an algorithmic approach to deployment of genetic testing in a timely fashion when faced with a patient with FSGS.
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Affiliation(s)
- Meenakshi Sambharia
- Division of Nephrology, Department of Internal MedicineUniversity of IowaIowa CityIowaUSA
| | - Prerna Rastogi
- Department of PathologyUniversity of IowaIowa CityIowaUSA
| | - Christie P. Thomas
- Division of Nephrology, Department of Internal MedicineUniversity of IowaIowa CityIowaUSA,Department of PediatricsUniversity of IowaIowa CityIowaUSA,The Iowa Institute of Human GeneticsUniversity of IowaIowa CityIowaUSA,Medical ServiceVeterans Affairs Medical CenterIowa CityIowaUSA
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Spectrum of NPHS1 and NPHS2 variants in egyptian children with focal segmental glomerular sclerosis: identification of six novel variants and founder effect. Mol Genet Genomics 2022; 297:689-698. [DOI: 10.1007/s00438-022-01877-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 02/20/2022] [Indexed: 01/10/2023]
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Li Q, Zhu L, Shi S, Xu D, Lv J, Zhang H. Case Report: A Pathogenic Missense Variant of WT1 Cosegregates With Proteinuria in a Six-Generation Chinese Family With IgA Nephropathy. Front Med (Lausanne) 2022; 8:810940. [PMID: 35174184 PMCID: PMC8841721 DOI: 10.3389/fmed.2021.810940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/30/2021] [Indexed: 11/13/2022] Open
Abstract
Immunoglobulin A (IgA) nephropathy (IgAN) is the most common type of primary glomerulonephritis worldwide. In addition to hematuria, proteinuria is observed in a considerable proportion of patients with IgAN and has proven to be a strong risk factor for disease progression. Although the exact pathogenesis of IgAN is still unclear, genetic factors are widely considered to play a role in its occurrence and development. Here, we investigated a large IgAN-associated pedigree of 47 members belonging to six generations. Two members of the family who presented with proteinuria and hematuria were diagnosed with IgAN through renal biopsy. Four other members also exhibited proteinuria or hematuria but without renal biopsy. Using whole-exome sequencing, we identified a likely pathogenic variant in WT1 (c.1397C>T; p.Ser466Phe) that cosegregated with proteinuria in the affected family members. In addition, another pathogenic variant in NPHS1 (c.3478C>T; p.Arg1160Ter) was identified; however, it did not cosegregate with abnormal proteinuria. Compared to individuals in the pedigree with only one heterozygous WT1 variant (c.1397C>T; p.Ser466Phe), the proband and her younger brother carried an additional WT1 variant (c.1433-10G>A) and presented with a more severe phenotype and rapid progression to end-stage kidney disease. Our findings suggest the WT1 missense variant (c.1397C>T; p.Ser466Phe)-induced primary podocyte injury might contribute to the proteinuria phenotype and IgAN progression in this pedigree.
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Rong L, Chen L, Rao J, Shen Q, Li G, Liu J, Mao J, Feng C, Wang X, Wang S, Kuang X, Huang W, Ma Q, Liu X, Ling C, Fu R, Gao X, Ding G, Yang H, Han M, Huang Z, Li Q, Zhang Q, Lin Y, Jiang X, Xu H. Genetic Variations and Clinical Features of NPHS1-Related Nephrotic Syndrome in Chinese Children: A Multicenter, Retrospective Study. Front Med (Lausanne) 2021; 8:771227. [PMID: 34859019 PMCID: PMC8632042 DOI: 10.3389/fmed.2021.771227] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 10/05/2021] [Indexed: 11/16/2022] Open
Abstract
Introduction: Few studies have addressed the genetic spectrum of NPHS1 variants in Chinese children with nephrotic syndrome. In this multicenter study, the clinical manifestations and features of NPHS1 variants in Chinese children with nephrotic syndrome were researched. Method: Genotypical and phenotypical data from 30 children affected by NPHS1 variants were collected from a multicenter registration system in China and analyzed retrospectively. Results: The patients were divided into two groups: congenital nephrotic syndrome (CNS [n = 24]) and non-CNS (early onset nephrotic syndrome [n = 6]). Renal biopsy was performed on four patients in the non-CNS group, revealing minimal change disease in three and focal segmental glomerulosclerosis in one. A total of 61 NPHS1 variants were detected, involving 25 novel variants. The "recurrent variants" included c.928G>A(p.Asp310Asn) in eight patients with CNS, followed by c.616C>A(p.Pro206Thr) in four, and c.2207T>C (p.Val736Ala) in three. Steroid treatment was applied in 29.2% (7/24)of the patients in the CNS group and 50% (3/6) of the patients in the non-CNS group. One patient in each group experienced complete remission but relapsed subsequently. Immunosuppressants were administered to three patients in the non-CNS group, eliciting an effective response. In the CNS group, three patients underwent renal transplantation and six died mainly from infection. Conclusion: Variants of NPHS1 cause CNS and early childhood-onset nephrotic syndrome. NPHS1 variants in Chinese individuals with nephrotic syndrome (NS) were mainly compound heterozygous variants, and c.928G>A(p.Asp310Asn) in exon 8 may act as a recurrent variant in the Chinese population, followed by c.616C>A(p.Pro206Thr) in exon 6. Steroids and immunosuppressants may be effective in selected patients.
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Affiliation(s)
- Liping Rong
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Lizhi Chen
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Jia Rao
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Qian Shen
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Guomin Li
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Jialu Liu
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
| | - Jianhua Mao
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chunyue Feng
- Department of Nephrology, The Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Xiaowen Wang
- Department of Nephrology and Rheumatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Si Wang
- Department of Nephrology and Rheumatology, Wuhan Children's Hospital (Wuhan Maternal and Child Healthcare Hospital), Tongji Medical College, Huazhong University of Science & Technology, Wuhan, China
| | - Xinyu Kuang
- Department of Nephrology and Rheumatology, Children's Hospital of Shanghai Jiaotong University, Shanghai, China
| | - Wenyan Huang
- Department of Nephrology and Rheumatology, Children's Hospital of Shanghai Jiaotong University, Shanghai, China
| | - Qingshan Ma
- Department of Pediatric Nephrology, First Hospital, Jilin University, Changchun, China
| | - Xiaorong Liu
- Department of Nephrology, Bejing Children's Hospital Affiliated to Capital University of Medical Science, Beijing, China
| | - Chen Ling
- Department of Nephrology, Bejing Children's Hospital Affiliated to Capital University of Medical Science, Beijing, China
| | - Rong Fu
- Department of Pediatrics, Puyang Oilfield General Hospital, Puyang, China
| | - Xiaojie Gao
- Department of Nephrology, Shenzhen Children's Hospital, Shenzhen, China
| | - Guixia Ding
- Department of Nephrology, Nanjing Children's Hospital Affiliated to Nanjing Medical University, Nanjing, China
| | - Huandan Yang
- Department of Nephrology, Xuzhou Children's Hospital, Xuzhou, China
| | - Mei Han
- Department of Nephrology, Children's Hospital of Dalian Medical University, Dalian, China
| | - Zhimin Huang
- Department of Pediatrics, Affiliated Hospital of Guangdong Medical University, Zhanjiang, China
| | - Qian Li
- Department of Pediatric Nephrology, Rheumatism and Immunology, Shandong Provincial Hospital Affiliated to Shandong University, Shandong, China
| | - Qiuye Zhang
- Department of Pediatrics, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yi Lin
- Department of Pediatrics, Affiliated Hospital of Qingdao University, Qingdao, China
| | - Xiaoyun Jiang
- Department of Pediatrics, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Hong Xu
- Department of Nephrology, Children's Hospital of Fudan University, Shanghai, China
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11
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Sever S. Role of actin cytoskeleton in podocytes. Pediatr Nephrol 2021; 36:2607-2614. [PMID: 33188449 PMCID: PMC8116355 DOI: 10.1007/s00467-020-04812-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 09/14/2020] [Accepted: 10/05/2020] [Indexed: 12/11/2022]
Abstract
The selectivity of the glomerular filter is established by physical, chemical, and signaling interplay among its three core constituents: glomerular endothelial cells, the glomerular basement membrane, and podocytes. Functional impairment or injury of any of these three components can lead to proteinuria. Podocytes are injured in many forms of human and experimental glomerular disease, including minimal change disease, focal segmental glomerulosclerosis, and diabetes mellitus. One of the earliest signs of podocyte injury is loss of their distinct structure, which is driven by dysregulated dynamics of the actin cytoskeleton. The status of the actin cytoskeleton in podocytes depends on a set of actin binding proteins, nucleators and inhibitors of actin polymerization, and regulatory GTPases. Mutations that alter protein function in each category have been implicated in glomerular diseases in humans and animal models. In addition, a growing body of studies suggest that pharmacological modifications of the actin cytoskeleton have the potential to become novel therapeutics for podocyte-dependent chronic kidney diseases. This review presents an overview of the essential proteins that establish actin cytoskeleton in podocytes and studies demonstrating the feasibility of drugging actin cytoskeleton in kidney diseases.
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Affiliation(s)
- Sanja Sever
- Harvard Medical School and Massachusetts General Hospital, Boston, MA, USA.
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12
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Impaired NEPHRIN localization in kidney organoids derived from nephrotic patient iPS cells. Sci Rep 2021; 11:3982. [PMID: 33597637 PMCID: PMC7890052 DOI: 10.1038/s41598-021-83501-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 02/01/2021] [Indexed: 01/07/2023] Open
Abstract
Mutations in the NPHS1 gene, which encodes NEPHRIN, cause congenital nephrotic syndrome, resulting from impaired slit diaphragm (SD) formation in glomerular podocytes. We previously reported NEPHRIN and SD abnormalities in the podocytes of kidney organoids generated from patient-derived induced pluripotent stem cells (iPSCs) with an NPHS1 missense mutation (E725D). However, the mechanisms underlying the disease may vary depending on the mutations involved, and thus generation of iPSCs from multiple patients is warranted. Here we established iPSCs from two additional patients with different NPHS1 mutations and examined the podocyte abnormalities in kidney organoids derived from these cells. One patient had truncating mutations, and NEPHRIN was undetectable in the resulting organoids. The other patient had a missense mutation (R460Q), and the mutant NEPHRIN in the organoids failed to accumulate on the podocyte surface to form SD precursors. However, the same mutant protein behaved normally when overexpressed in heterologous cells, suggesting that NEPHRIN localization is cell context-dependent. The localization of another SD-associated protein, PODOCIN, was impaired in both types of mutant organoids in a cell domain-specific manner. Thus, the new iPSC lines and resultant kidney organoids will be useful resources for dissecting the disease mechanisms, as well as for drug development for therapies.
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13
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Gao W, Liu Y, Fan L, Zheng B, Jefferson JR, Wang S, Zhang H, Fang X, Nguyen BV, Zhu T, Roman RJ, Fan F. Role of γ-adducin in actin cytoskeleton rearrangements in podocyte pathophysiology. Am J Physiol Renal Physiol 2021; 320:F97-F113. [PMID: 33308016 PMCID: PMC7847051 DOI: 10.1152/ajprenal.00423.2020] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 11/24/2020] [Accepted: 11/24/2020] [Indexed: 12/16/2022] Open
Abstract
We recently reported that the enhanced susceptibility to chronic kidney disease (CKD) in the fawn-hooded hypertensive (FHH) rat is caused, at least in part, by a mutation in γ-adducin (ADD3) that attenuates renal vascular function. The present study explored whether Add3 contributes to the modulation of podocyte structure and function using FHH and FHH.Add3 transgenic rats. The expression of ADD3 on the membrane of primary podocytes isolated from FHH was reduced compared with FHH.Add3 transgenic rats. We found that F-actin nets, which are typically localized in the lamellipodia, replaced unbranched stress fibers in conditionally immortalized mouse podocytes transfected with Add3 Dicer-substrate short interfering RNA (DsiRNA) and primary podocytes isolated from FHH rats. There were increased F/G-actin ratios and expression of the Arp2/3 complexes throughout FHH podocytes in association with reduced synaptopodin and RhoA but enhanced Rac1 and CDC42 expression in the renal cortex, glomeruli, and podocytes of FHH rats. The expression of nephrin at the slit diaphragm and the levels of focal adhesion proteins integrin-α3 and integrin-β1 were decreased in the glomeruli of FHH rats. Cell migration was enhanced and adhesion was reduced in podocytes of FHH rats as well as in immortalized mouse podocytes transfected with Add3 DsiRNA. Mean arterial pressures were similar in FHH and FHH.Add3 transgenic rats at 16 wk of age; however, FHH rats exhibited enhanced proteinuria associated with podocyte foot process effacement. These results demonstrate that reduced ADD3 function in FHH rats alters baseline podocyte pathophysiology by rearrangement of the actin cytoskeleton at the onset of proteinuria in young animals.
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Affiliation(s)
- Wenjun Gao
- Department of Urology, Zhongshan Hospital, Fudan University, Shanghai, China
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Yedan Liu
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Letao Fan
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Baoying Zheng
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Joshua R Jefferson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Shaoxun Wang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Huawei Zhang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Xing Fang
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Bond V Nguyen
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Tongyu Zhu
- Department of Urology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Richard J Roman
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
| | - Fan Fan
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi
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14
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Yamada H, Shirata N, Makino S, Miyake T, Trejo JAO, Yamamoto-Nonaka K, Kikyo M, Empitu MA, Kadariswantiningsih IN, Kimura M, Ichimura K, Yokoi H, Mukoyama M, Hotta A, Nishimori K, Yanagita M, Asanuma K. MAGI-2 orchestrates the localization of backbone proteins in the slit diaphragm of podocytes. Kidney Int 2020; 99:382-395. [PMID: 33144214 DOI: 10.1016/j.kint.2020.09.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 08/22/2020] [Accepted: 09/10/2020] [Indexed: 01/19/2023]
Abstract
Podocytes are highly specialized cells within the glomerulus that are essential for ultrafiltration. The slit diaphragm between the foot processes of podocytes functions as a final filtration barrier to prevent serum protein leakage into urine. The slit-diaphragm consists mainly of Nephrin and Neph1, and localization of these backbone proteins is essential to maintaining the integrity of the glomerular filtration barrier. However, the mechanisms that regulate the localization of these backbone proteins have remained elusive. Here, we focused on the role of membrane-associated guanylate kinase inverted 2 (MAGI-2) in order to investigate mechanisms that orchestrate localization of slit-diaphragm backbone proteins. MAGI-2 downregulation coincided with a reduced expression of slit-diaphragm backbone proteins in human kidneys glomerular disease such as focal segmental glomerulosclerosis or IgA nephropathy. Podocyte-specific deficiency of MAGI-2 in mice abrogated localization of Nephrin and Neph1 independently of other scaffold proteins. Although a deficiency of zonula occuldens-1 downregulated the endogenous Neph1 expression, MAGI-2 recovered Neph1 expression at the cellular edge in cultured podocytes. Additionally, overexpression of MAGI-2 preserved Nephrin localization to intercellular junctions. Co-immunoprecipitation and pull-down assays also revealed the importance of the PDZ domains of MAGI-2 for the interaction between MAGI-2 and slit diaphragm backbone proteins in podocytes. Thus, localization and stabilization of Nephrin and Neph1 in intercellular junctions is regulated mainly via the PDZ domains of MAGI-2 together with other slit-diaphragm scaffold proteins. Hence, these findings may elucidate a mechanism by which the backbone proteins are maintained.
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Affiliation(s)
- Hiroyuki Yamada
- Department of Nephrology, Graduate School of Medicine, Chiba University, Chiba, Japan; Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Naritoshi Shirata
- Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharmaceutical Corporation, Saitama, Japan
| | - Shinichi Makino
- Department of Nephrology, Graduate School of Medicine, Chiba University, Chiba, Japan; Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Takafumi Miyake
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | | | - Kanae Yamamoto-Nonaka
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Mitsuhiro Kikyo
- Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Sohyaku, Innovative Research Division, Mitsubishi Tanabe Pharmaceutical Corporation, Saitama, Japan
| | - Maulana A Empitu
- Department of Nephrology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | | | - Maiko Kimura
- Department of Nephrology, Graduate School of Medicine, Chiba University, Chiba, Japan
| | - Koichiro Ichimura
- Department of Anatomy and Life Structure, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Hideki Yokoi
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan
| | - Masashi Mukoyama
- Department of Nephrology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan
| | - Akitsu Hotta
- Department of Reprogramming Science, Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto, Japan
| | - Katsuhiko Nishimori
- Department of Obesity and Inflammation Research, Fukushima Medical University, Fukushima, Japan
| | - Motoko Yanagita
- Department of Nephrology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Institute for the Advanced Study of Human Biology (ASHBi), Kyoto University, Kyoto, Japan
| | - Katsuhiko Asanuma
- Department of Nephrology, Graduate School of Medicine, Chiba University, Chiba, Japan; Medical Innovation Center, TMK Project, Graduate School of Medicine, Kyoto University, Kyoto, Japan.
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15
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Tokhmafshan F, Dickinson K, Akpa MM, Brasell E, Huertas P, Goodyer PR. A no-nonsense approach to hereditary kidney disease. Pediatr Nephrol 2020; 35:2031-2042. [PMID: 31807928 DOI: 10.1007/s00467-019-04394-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Revised: 07/05/2019] [Accepted: 10/07/2019] [Indexed: 01/12/2023]
Abstract
The advent of a new class of aminoglycosides with increased translational readthrough of nonsense mutations and reduced toxicity offers a new therapeutic strategy for a subset of patients with hereditary kidney disease. The renal uptake and retention of aminoglycosides at a high intracellular concentration makes the kidney an ideal target for this approach. In this review, we explore the potential of aminoglycoside readthrough therapy in a number of hereditary kidney diseases and discuss the therapeutic window of opportunity for subclasses of each disease, when caused by nonsense mutations.
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Affiliation(s)
- Fatima Tokhmafshan
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada
| | - Kyle Dickinson
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada.,Department of Experimental Medicine, McGill University, Montreal, Canada
| | - Murielle M Akpa
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada
| | - Emma Brasell
- Department of Human Genetics, McGill University, Montreal, Canada
| | | | - Paul R Goodyer
- Research Institute of the McGill University Health Center, 1001 Décarie Boulevard, EM1.2232, Montreal, QC, H4A 3J1, Canada. .,Department of Experimental Medicine, McGill University, Montreal, Canada. .,Department of Human Genetics, McGill University, Montreal, Canada. .,Department of Pediatrics, McGill University, Montreal, Canada.
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16
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Yıldız G, Torun Bayram M, Soylu A, Kavukçu S. A novel NPHS1 mutation associated with temporary elevation of maternal serum alfa-fetoprotein and late onset of proteinuria. Int Urol Nephrol 2020; 53:391-392. [PMID: 32944892 DOI: 10.1007/s11255-020-02645-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Accepted: 09/07/2020] [Indexed: 02/05/2023]
Affiliation(s)
- Gizem Yıldız
- Department of Pediatric Nephrology, Dokuz Eylül University Medical Faculty, Balçova, 35340, Izmir, Turkey
| | - Meral Torun Bayram
- Department of Pediatric Nephrology, Dokuz Eylül University Medical Faculty, Balçova, 35340, Izmir, Turkey
| | - Alper Soylu
- Department of Pediatric Nephrology and Rheumatology, Dokuz Eylül University Medical Faculty, Izmir, Turkey.
| | - Salih Kavukçu
- Department of Pediatric Nephrology and Rheumatology, Dokuz Eylül University Medical Faculty, Izmir, Turkey
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17
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Li G, Kidd J, Kaspar C, Dempsey S, Bhat OM, Camus S, Ritter JK, Gehr TWB, Gulbins E, Li PL. Podocytopathy and Nephrotic Syndrome in Mice with Podocyte-Specific Deletion of the Asah1 Gene: Role of Ceramide Accumulation in Glomeruli. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 190:1211-1223. [PMID: 32194052 DOI: 10.1016/j.ajpath.2020.02.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 02/20/2020] [Indexed: 12/26/2022]
Abstract
Lysosomal acid ceramidase (Ac) has been shown to be critical for ceramide hydrolysis and regulation of lysosome function and cellular homeostasis. In the present study, we generated a knockout mouse strain (Asah1fl/fl/PodoCre) with a podocyte-specific deletion of the α subunit (main catalytic subunit) of Ac. Although no significant morphologic changes in glomeruli were observed in these mice under light microscope, severe proteinuria and albuminuria were found in these podocyte-specific knockout mice compared with control genotype littermates. Transmission electron microscopic analysis showed that podocytes of the knockout mice had distinctive foot process effacement and microvillus formation. These functional and morphologic changes indicate the development of nephrotic syndrome in mice bearing the Asah1 podocyte-specific gene deletion. Ceramide accumulation determined by liquid chromatography-tandem mass spectrometry was demonstrated in isolated glomeruli of Asah1fl/fl/PodoCre mice compared with their littermates. By crossbreeding Asah1fl/fl/PodoCre mice with Smpd1-/- mice, we also produced a double knockout strain, Smpd1-/-/Asah1fl/fl/PodoCre, that also lacks Smpd1, the acid sphingomyelinase that hydrolyzes sphingomyelin to ceramide. These mice exhibited significantly lower levels of glomerular ceramide with decreased podocyte injury compared with Asah1fl/fl/PodoCre mice. These results strongly suggest that lysosomal Ac in podocytes is essential for the maintenance of the structural and functional integrity of podocytes.
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Affiliation(s)
- Guangbi Li
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Jason Kidd
- Division of Nephrology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Cristin Kaspar
- Division of Nephrology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Sara Dempsey
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Owais M Bhat
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Sarah Camus
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Joseph K Ritter
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia
| | - Todd W B Gehr
- Division of Nephrology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Erich Gulbins
- Department of Molecular Biology, University of Duisburg-Essen, Essen, Germany
| | - Pin-Lan Li
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, Virginia.
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18
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Hao GX, Song LL, Zhang DF, Su LQ, Jacqz-Aigrain E, Zhao W. Off-label use of tacrolimus in children with glomerular disease: Effectiveness, safety and pharmacokinetics. Br J Clin Pharmacol 2020; 86:274-284. [PMID: 31725919 DOI: 10.1111/bcp.14174] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/21/2019] [Accepted: 11/04/2019] [Indexed: 12/13/2022] Open
Abstract
Glomerular diseases are leading causes of end-stage renal disease in children. Tacrolimus is frequently used off-label in the treatment of glomerular diseases. The effectiveness, safety and pharmacokinetic data of tacrolimus in the treatment of glomerular diseases in children are reviewed in this paper to provide evidence to support its rational use in clinical practice. The remission rates in previously published studies were different. In 19 clinical trials on children with nephrotic syndrome, the overall remission rate was 52.6-97.6%. In four clinical trials on children with lupus nephritis, the overall remission rate was 81.8-89.5%. In a pilot study with paediatric Henoch-Schönlein purpura nephritis patients, the overall remission rate was 100.0%. Infection, nephrotoxicity, gastrointestinal symptoms and hypertension are the most common adverse events. Body weight, age, CYP3A5 genotype, cystatin-C and daily dose of tacrolimus may have significant effects on the pharmacokinetics of tacrolimus in children with glomerular disease. More prospective controlled trials with long follow-up are needed to demonstrate definitely the effectiveness, safety and pharmacokinetics of tacrolimus in children with glomerular diseases.
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Affiliation(s)
- Guo-Xiang Hao
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Shandong University, Jinan, China
| | - Lin-Lin Song
- Department of Pharmacy, Shandong Provincial Qianfoshan Hospital, the First Hospital Affiliated with Shandong First Medical University, Jinan, China
| | - Dong-Feng Zhang
- Department of Pediatric Nephrology, Children's Hospital of Hebei Province affiliated to Hebei Medical University, Shijiazhuang, China
| | - Le-Qun Su
- Department of Pharmacy, Shandong Provincial Qianfoshan Hospital, the First Hospital Affiliated with Shandong First Medical University, Jinan, China
| | - Evelyne Jacqz-Aigrain
- Department of Pediatric Pharmacology and Pharmacogenetics, Hôpital Robert Debré, APHP, Paris, France
| | - Wei Zhao
- Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Shandong University, Jinan, China.,Department of Pharmacy, Shandong Provincial Qianfoshan Hospital, the First Hospital Affiliated with Shandong First Medical University, Jinan, China
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19
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Wang M, Chun J, Genovese G, Knob AU, Benjamin A, Wilkins MS, Friedman DJ, Appel GB, Lifton RP, Mane S, Pollak MR. Contributions of Rare Gene Variants to Familial and Sporadic FSGS. J Am Soc Nephrol 2019; 30:1625-1640. [PMID: 31308072 DOI: 10.1681/asn.2019020152] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/25/2019] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Over the past two decades, the importance of genetic factors in the development of FSGS has become increasingly clear. However, despite many known monogenic causes of FSGS, single gene defects explain only 30% of cases. METHODS To investigate mutations underlying FSGS, we sequenced 662 whole exomes from individuals with sporadic or familial FSGS. After quality control, we analyzed the exome data from 363 unrelated family units with sporadic or familial FSGS and compared this to data from 363 ancestry-matched controls. We used rare variant burden tests to evaluate known disease-associated genes and potential new genes. RESULTS We validated several FSGS-associated genes that show a marked enrichment of deleterious rare variants among the cases. However, for some genes previously reported as FSGS related, we identified rare variants at similar or higher frequencies in controls. After excluding such genes, 122 of 363 cases (33.6%) had rare variants in known disease-associated genes, but 30 of 363 controls (8.3%) also harbored rare variants that would be classified as "causal" if detected in cases; applying American College of Medical Genetics filtering guidelines (to reduce the rate of false-positive claims that a variant is disease related) yielded rates of 24.2% in cases and 5.5% in controls. Highly ranked new genes include SCAF1, SETD2, and LY9. Network analysis showed that top-ranked new genes were located closer than a random set of genes to known FSGS genes. CONCLUSIONS Although our analysis validated many known FSGS-causing genes, we detected a nontrivial number of purported "disease-causing" variants in controls, implying that filtering is inadequate to allow clinical diagnosis and decision making. Genetic diagnosis in patients with FSGS is complicated by the nontrivial rate of variants in known FSGS genes among people without kidney disease.
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Affiliation(s)
- Minxian Wang
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.,Department of Medicine, Harvard Medical School, Boston, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Justin Chun
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.,Department of Medicine, Harvard Medical School, Boston, Massachusetts.,Division of Nephrology, Department of Medicine, University of Calgary, Cumming School of Medicine, Calgary, Alberta, Canada
| | - Giulio Genovese
- Stanley Center for Psychiatric Research, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Andrea U Knob
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Ava Benjamin
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Maris S Wilkins
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - David J Friedman
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.,Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Gerald B Appel
- Division of Nephrology, Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York
| | - Richard P Lifton
- Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, New York; and
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut
| | - Martin R Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts; .,Department of Medicine, Harvard Medical School, Boston, Massachusetts.,Program in Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
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20
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Dlugos CP, Picciotto C, Lepa C, Krakow M, Stöber A, Eddy ML, Weide T, Jeibmann A, P Krahn M, Van Marck V, Klingauf J, Ricker A, Wedlich-Söldner R, Pavenstädt H, Klämbt C, George B. Nephrin Signaling Results in Integrin β1 Activation. J Am Soc Nephrol 2019; 30:1006-1019. [PMID: 31097607 DOI: 10.1681/asn.2018040362] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 03/18/2019] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Patients with certain mutations in the gene encoding the slit diaphragm protein Nephrin fail to develop functional slit diaphragms and display severe proteinuria. Many adult-onset glomerulopathies also feature alterations in Nephrin expression and function. Nephrin signals from the podocyte slit diaphragm to the Actin cytoskeleton by recruiting proteins that can interact with C3G, a guanine nucleotide exchange factor of the small GTPase Rap1. Because Rap activity affects formation of focal adhesions, we hypothesized that Nephrin transmits signals to the Integrin receptor complex, which mediates podocyte adhesion to the extracellular matrix. METHODS To investigate Nephrin's role in transmitting signals to the Integrin receptor complex, we conducted genetic studies in Drosophila nephrocytes and validated findings from Drosophila in a cultured human podocyte model. RESULTS Drosophila nephrocytes form a slit diaphragm-like filtration barrier and express the Nephrin ortholog Sticks and stones (Sns). A genetic screen identified c3g as necessary for nephrocyte function. In vivo, nephrocyte-specific gene silencing of sns or c3g compromised nephrocyte filtration and caused nephrocyte diaphragm defects. Nephrocytes with impaired Sns or C3G expression displayed an altered localization of Integrin and the Integrin-associated protein Talin. Furthermore, gene silencing of c3g partly rescued nephrocyte diaphragm defects of an sns overexpression phenotype, pointing to genetic interaction of sns and c3g in nephrocytes. We also found that activated Nephrin recruited phosphorylated C3G and resulted in activation of Integrin β1 in cultured podocytes. CONCLUSIONS Our findings suggest that Nephrin can mediate a signaling pathway that results in activation of Integrin β1 at focal adhesions, which may affect podocyte attachment to the extracellular matrix.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - Christian Klämbt
- Neurobiology, Westfälische-Wilhelms University Münster, Münster, Germany
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21
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Genetic testing in steroid-resistant nephrotic syndrome: why, who, when and how? Pediatr Nephrol 2019; 34:195-210. [PMID: 29181713 PMCID: PMC6311200 DOI: 10.1007/s00467-017-3838-6] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 10/24/2017] [Accepted: 10/25/2017] [Indexed: 12/23/2022]
Abstract
Steroid-resistant nephrotic syndrome (SRNS) is a common cause of chronic kidney disease in childhood and has a significant risk of rapid progression to end-stage renal disease. The identification of over 50 monogenic causes of SRNS has revealed dysfunction in podocyte-associated proteins in the pathogenesis of proteinuria, highlighting their essential role in glomerular function. Recent technological advances in high-throughput sequencing have enabled indication-driven genetic panel testing for patients with SRNS. The availability of genetic testing, combined with the significant phenotypic variability of monogenic SRNS, poses unique challenges for clinicians when directing genetic testing. This highlights the need for clear clinical guidelines that provide a systematic approach for mutational screening in SRNS. The likelihood of identifying a causative mutation is inversely related to age at disease onset and is increased with a positive family history or the presence of extra-renal manifestations. An unequivocal molecular diagnosis could allow for a personalised treatment approach with weaning of immunosuppressive therapy, avoidance of renal biopsy and provision of accurate, well-informed genetic counselling. Identification of novel causative mutations will continue to unravel the pathogenic mechanisms of glomerular disease and provide new insights into podocyte biology and glomerular function.
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22
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Abstract
PRACTICE GAP Pediatricians must be aware of screening indications and the evaluation and management of a child with hematuria and/or proteinuria. OBJECTIVES After completing this article, readers should be able to: 1. Understand the common causes of proteinuria and hematuria and be able to differentiate between benign and serious causes. 2. Describe screening techniques for initial evaluation of hematuria and proteinuria. 3. Recognize the criteria for diagnosis of proteinuria and hematuria. 4. Plan the appropriate initial evaluation for hematuria and proteinuria and interpret laboratory findings essential for diagnosis. 5. Recognize serious causes of hematuria and proteinuria that warrant immediate referral.
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23
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Mikó Á, K Menyhárd D, Kaposi A, Antignac C, Tory K. The mutation-dependent pathogenicity of NPHS2 p.R229Q: A guide for clinical assessment. Hum Mutat 2018; 39:1854-1860. [PMID: 30260545 DOI: 10.1002/humu.23660] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 09/24/2018] [Accepted: 09/25/2018] [Indexed: 11/08/2022]
Abstract
NPHS2, encoding podocin, is the major gene implicated in steroid-resistant nephrotic syndrome. Its c.686G>A, p.R229Q variant is the first human variant with a mutation-dependent pathogenicity; it is only pathogenic when trans-associated to specific mutations. Secondary to its high allele frequency in the European, South Asian, African, and Latino populations, its benign trans-associations can be accidentally identified in affected patients. Distinguishing pathogenic and benign p.R229Q associations can be challenging. In this paper, we present the currently known pathogenic and benign associations, and show that a rare p.R229Q association can be considered pathogenic if the variant in trans meets the following criteria; it affects the 270-351 residues and alters but does not disrupt the oligomerization, its p.R229Q association is found in a family with slowly progressing focal segmental glomerulosclerosis, but is expected to be rare in the general population (<1:106 ). We show that >15% of the p.R229Q associations identified so far in patients are benign.
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Affiliation(s)
- Ágnes Mikó
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary.,Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
| | - Dóra K Menyhárd
- MTA-ELTE Protein Modeling Research Group and Laboratory of Structural Chemistry and Biology, Eötvös Loránd University, Budapest, Hungary
| | - Ambrus Kaposi
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary
| | - Corinne Antignac
- Laboratory of Hereditary Kidney Diseases, INSERM, UMR 1163, Imagine Institute, Université Paris Descartes-Sorbonne Paris Cité, Paris, France.,Assistance Publique - Hôpitaux de Paris, Hôpital Necker-Enfants Malades, Département de Génétique, Paris, France
| | - Kálmán Tory
- MTA-SE Lendület Nephrogenetic Laboratory, Budapest, Hungary.,Semmelweis University, Ist Department of Pediatrics, Budapest, Hungary
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24
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Cooper CJ, Dutta NT, Martin CE, Piscione TD, Thorner PS, Jones N. Characterization of a novel disease-associated mutation within NPHS1 and its effects on nephrin phosphorylation and signaling. PLoS One 2018; 13:e0203905. [PMID: 30212551 PMCID: PMC6136785 DOI: 10.1371/journal.pone.0203905] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 08/29/2018] [Indexed: 12/22/2022] Open
Abstract
Mutations in the transmembrane protein nephrin (encoded by NPHS1) underlie nearly half of all cases of congenital nephrotic syndrome (CNS), which is caused by aberrations in the blood filtering function of glomerular podocytes. Nephrin directly contributes to the structure of the filtration barrier, and it also serves as a signaling scaffold in podocytes, undergoing tyrosine phosphorylation on its cytoplasmic tail to recruit intracellular effector proteins. Nephrin phosphorylation is lost in several human and experimental models of glomerular disease, and genetic studies have confirmed its importance in maintenance of the filtration barrier. To date, however, the effect of CNS-associated NPHS1 variants on nephrin phosphorylation remains to be determined, which hampers genotype-phenotype correlations. Here, we have characterized a novel nephrin sequence variant, A419T, which is expressed along with C623F in a patient presenting with CNS. Nephrin localization is altered in kidney biopsies, and we further demonstrate reduced surface expression and ER retention of A419T and C623F in cultured cells. Moreover, we show that both mutations impair nephrin tyrosine phosphorylation, and they exert dominant negative effects on wildtype nephrin signaling. Our findings thus reveal that missense mutations in the nephrin extracellular region can impact nephrin signaling, and they uncover a potential pathomechanism to explain the spectrum of clinical severity seen with mild NPHS1 mutations.
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Affiliation(s)
- C. James Cooper
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Nikkita T. Dutta
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Claire E. Martin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Tino D. Piscione
- Division of Nephrology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Paul S. Thorner
- Department of Pathology and Laboratory Medicine, The Hospital for Sick Children and University of Toronto, Toronto, ON, Canada
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
- * E-mail:
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25
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Yu SMW, Nissaisorakarn P, Husain I, Jim B. Proteinuric Kidney Diseases: A Podocyte's Slit Diaphragm and Cytoskeleton Approach. Front Med (Lausanne) 2018; 5:221. [PMID: 30255020 PMCID: PMC6141722 DOI: 10.3389/fmed.2018.00221] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/18/2018] [Indexed: 01/19/2023] Open
Abstract
Proteinuric kidney diseases are a group of disorders with diverse pathological mechanisms associated with significant losses of protein in the urine. The glomerular filtration barrier (GFB), comprised of the three important layers, the fenestrated glomerular endothelium, the glomerular basement membrane (GBM), and the podocyte, dictates that disruption of any one of these structures should lead to proteinuric disease. Podocytes, in particular, have long been considered as the final gatekeeper of the GFB. This specialized visceral epithelial cell contains a complex framework of cytoskeletons forming foot processes and mediate important cell signaling to maintain podocyte health. In this review, we will focus on slit diaphragm proteins such as nephrin, podocin, TRPC6/5, as well as cytoskeletal proteins Rho/small GTPases and synaptopodin and their respective roles in participating in the pathogenesis of proteinuric kidney diseases. Furthermore, we will summarize the potential therapeutic options targeting the podocyte to treat this group of kidney diseases.
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Affiliation(s)
- Samuel Mon-Wei Yu
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States
| | | | - Irma Husain
- Department of Medicine, James J. Peters VA Medical Center, Bronx, NY, United States
| | - Belinda Jim
- Department of Medicine, Jacobi Medical Center, Bronx, NY, United States.,Renal Division, Jacobi Medical Center, Bronx, NY, United States
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26
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Hermle T, Schneider R, Schapiro D, Braun DA, van der Ven AT, Warejko JK, Daga A, Widmeier E, Nakayama M, Jobst-Schwan T, Majmundar AJ, Ashraf S, Rao J, Finn LS, Tasic V, Hernandez JD, Bagga A, Jalalah SM, El Desoky S, Kari JA, Laricchia KM, Lek M, Rehm HL, MacArthur DG, Mane S, Lifton RP, Shril S, Hildebrandt F. GAPVD1 and ANKFY1 Mutations Implicate RAB5 Regulation in Nephrotic Syndrome. J Am Soc Nephrol 2018; 29:2123-2138. [PMID: 29959197 PMCID: PMC6065084 DOI: 10.1681/asn.2017121312] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 05/24/2018] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of CKD. The discovery of monogenic causes of SRNS has revealed specific pathogenetic pathways, but these monogenic causes do not explain all cases of SRNS. METHODS To identify novel monogenic causes of SRNS, we screened 665 patients by whole-exome sequencing. We then evaluated the in vitro functional significance of two genes and the mutations therein that we discovered through this sequencing and conducted complementary studies in podocyte-like Drosophila nephrocytes. RESULTS We identified conserved, homozygous missense mutations of GAPVD1 in two families with early-onset NS and a homozygous missense mutation of ANKFY1 in two siblings with SRNS. GAPVD1 and ANKFY1 interact with the endosomal regulator RAB5. Coimmunoprecipitation assays indicated interaction between GAPVD1 and ANKFY1 proteins, which also colocalized when expressed in HEK293T cells. Silencing either protein diminished the podocyte migration rate. Compared with wild-type GAPVD1 and ANKFY1, the mutated proteins produced upon ectopic expression of GAPVD1 or ANKFY1 bearing the patient-derived mutations exhibited altered binding affinity for active RAB5 and reduced ability to rescue the knockout-induced defect in podocyte migration. Coimmunoprecipitation assays further demonstrated a physical interaction between nephrin and GAPVD1, and immunofluorescence revealed partial colocalization of these proteins in rat glomeruli. The patient-derived GAPVD1 mutations reduced nephrin-GAPVD1 binding affinity. In Drosophila, silencing Gapvd1 impaired endocytosis and caused mistrafficking of the nephrin ortholog. CONCLUSIONS Mutations in GAPVD1 and probably in ANKFY1 are novel monogenic causes of NS. The discovery of these genes implicates RAB5 regulation in the pathogenesis of human NS.
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Affiliation(s)
- Tobias Hermle
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
- Renal Division, University Medical Center Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Ronen Schneider
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - David Schapiro
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Daniela A Braun
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amelie T van der Ven
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jillian K Warejko
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ankana Daga
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eugen Widmeier
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Makiko Nakayama
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Tilman Jobst-Schwan
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amar J Majmundar
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Shazia Ashraf
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Jia Rao
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Laura S Finn
- Department of Pathology, Seattle Children's Hospital, University of Washington, Seattle, Washington
| | - Velibor Tasic
- Department of Pediatric Nephrology, Medical Faculty Skopje, University Children's Hospital, Skopje, Macedonia
| | - Joel D Hernandez
- Department of Pediatric Nephrology, Providence Sacred Heart Medical Center and Children's Hospital, Spokane, Washington
| | - Arvind Bagga
- Division of Nephrology, All India Institute of Medical Sciences, New Delhi, India
| | | | - Sherif El Desoky
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Jameela A Kari
- Pediatric Nephrology Center of Excellence and Pediatric Department, Faculty of Medicine, King Abdulaziz University, Jeddah, Kingdom of Saudi Arabia
| | - Kristen M Laricchia
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Monkol Lek
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Heidi L Rehm
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Daniel G MacArthur
- Broad Center for Mendelian Genetics, Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, Massachusetts
| | - Shrikant Mane
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut; and
| | - Richard P Lifton
- Department of Genetics, Yale University School of Medicine, New Haven, Connecticut; and
- Laboratory of Human Genetics and Genomics, The Rockefeller University, New York, New York
| | - Shirlee Shril
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Friedhelm Hildebrandt
- Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts;
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27
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Lepori N, Zand L, Sethi S, Fernandez-Juarez G, Fervenza FC. Clinical and pathological phenotype of genetic causes of focal segmental glomerulosclerosis in adults. Clin Kidney J 2018; 11:179-190. [PMID: 29644057 PMCID: PMC5888331 DOI: 10.1093/ckj/sfx143] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 11/17/2017] [Indexed: 02/07/2023] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a histologic lesion resulting from a variety of pathogenic processes that cause injury to the podocytes. Recently, mutations in more than 50 genes expressed in podocyte or glomerular basement membrane were identified as causing genetic forms of FSGS, the majority of which are characterized by onset in childhood. The prevalence of adult-onset genetic FSGS is likely to be underestimated and its clinical and histological features have not been clearly described. A small number of studies of adult-onset genetic FSGS showed that there is heterogeneity in clinical and histological findings, with a presentation ranging from sub-nephrotic proteinuria to full nephrotic syndrome. A careful evaluation of adult-onset FSGS that do not have typical features of primary or secondary FSGS (familial cases, resistance to immunosuppression and absence of evident cause of secondary FSGS) should include a genetic evaluation. Indeed, recognizing genetic forms of adult-onset FSGS is of the utmost importance, given that this diagnosis will have major implications on treatment strategies, selecting of living-related kidney donor and renal transplantation success.
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Affiliation(s)
- Nicola Lepori
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
- Division of Nephrology and Dialysis, Azienda Ospedaliera G. Brotzu, Cagliari, Italy
| | - Ladan Zand
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
| | - Sanjeev Sethi
- Division of Anatomic Pathology, Mayo Clinic, Rochester, MN, USA
| | - Gema Fernandez-Juarez
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, USA
- Nephrology Division, Hospital Universitario Fundacion Alcorcon, Madrid, Spain
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28
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Levi M, Myakala K, Wang X. SRGAP2a: A New Player That Modulates Podocyte Cytoskeleton and Injury in Diabetes. Diabetes 2018; 67:550-551. [PMID: 29559512 PMCID: PMC5860859 DOI: 10.2337/dbi17-0050] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 12/28/2017] [Indexed: 11/13/2022]
Affiliation(s)
- Moshe Levi
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC
| | - Komuraiah Myakala
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC
| | - Xiaoxin Wang
- Department of Biochemistry and Molecular & Cellular Biology, Georgetown University, Washington, DC
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29
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Cil O, Perwad F. Monogenic Causes of Proteinuria in Children. Front Med (Lausanne) 2018; 5:55. [PMID: 29594119 PMCID: PMC5858124 DOI: 10.3389/fmed.2018.00055] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 02/15/2018] [Indexed: 01/02/2023] Open
Abstract
Glomerular disease is a common cause for proteinuria and chronic kidney disease leading to end-stage renal disease requiring dialysis or kidney transplantation in children. Nephrotic syndrome in children is diagnosed by the presence of a triad of proteinuria, hypoalbuminemia, and edema. Minimal change disease is the most common histopathological finding in children and adolescents with nephrotic syndrome. Focal segmental sclerosis is also found in children and is the most common pathological finding in patients with monogenic causes of nephrotic syndrome. Current classification system for nephrotic syndrome is based on response to steroid therapy as a majority of patients develop steroid sensitive nephrotic syndrome regardless of histopathological diagnosis or the presence of genetic mutations. Recent studies investigating the genetics of nephrotic syndrome have shed light on the pathophysiology and mechanisms of proteinuria in nephrotic syndrome. Gene mutations have been identified in several subcellular compartments of the glomerular podocyte and play a critical role in mitochondrial function, actin cytoskeleton dynamics, cell-matrix interactions, slit diaphragm, and podocyte integrity. A subset of genetic mutations are known to cause nephrotic syndrome that is responsive to immunosuppressive therapy but clinical data are limited with respect to renal prognosis and disease progression in a majority of patients. To date, more than 50 genes have been identified as causative factors in nephrotic syndrome in children and adults. As genetic testing becomes more prevalent and affordable, we expect rapid advances in our understanding of mechanisms of proteinuria and genetic diagnosis will help direct future therapy for individual patients.
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Affiliation(s)
- Onur Cil
- Department of Pediatrics, Division of Nephrology, University of California San Francisco, San Francisco, CA, United States
| | - Farzana Perwad
- Department of Pediatrics, Division of Nephrology, University of California San Francisco, San Francisco, CA, United States
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30
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31
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Sen ES, Dean P, Yarram-Smith L, Bierzynska A, Woodward G, Buxton C, Dennis G, Welsh GI, Williams M, Saleem MA. Clinical genetic testing using a custom-designed steroid-resistant nephrotic syndrome gene panel: analysis and recommendations. J Med Genet 2017; 54:795-804. [PMID: 28780565 PMCID: PMC5740557 DOI: 10.1136/jmedgenet-2017-104811] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Revised: 06/27/2017] [Accepted: 06/29/2017] [Indexed: 01/16/2023]
Abstract
BACKGROUND There are many single-gene causes of steroid-resistant nephrotic syndrome (SRNS) and the list continues to grow rapidly. Prompt comprehensive diagnostic testing is key to realising the clinical benefits of a genetic diagnosis. This report describes a bespoke-designed, targeted next-generation sequencing (NGS) diagnostic gene panel assay to detect variants in 37 genes including the ability to identify copy number variants (CNVs). METHODS This study reports results of 302 patients referred for SRNS diagnostic gene panel analysis. Phenotype and clinical impact data were collected using a standard proforma. Candidate variants detected by NGS were confirmed by Sanger sequencing/Multiplex Ligation-dependent Probe Amplification with subsequent family segregation analysis where possible. RESULTS Clinical presentation was nephrotic syndrome in 267 patients and suspected Alport syndrome (AS) in 35. NGS panel testing determined a likely genetic cause of disease in 44/220 (20.0%) paediatric and 10/47 (21.3%) adult nephrotic cases, and 17/35 (48.6%) of haematuria/AS patients. Of 71 patients with genetic disease, 32 had novel pathogenic variants without a previous disease association including two with deletions of one or more exons of NPHS1 or NPHS2. CONCLUSION Gene panel testing provides a genetic diagnosis in a significant number of patients presenting with SRNS or suspected AS. It should be undertaken at an early stage of the care pathway and include the ability to detect CNVs as an emerging mechanism for genes associated with this condition. Use of clinical genetic testing after diagnosis of SRNS has the potential to stratify patients and assist decision-making regarding management.
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Affiliation(s)
- Ethan S Sen
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
- Bristol Royal Hospital for Children, Bristol, UK
| | - Philip Dean
- Bristol Genetics Laboratory, Southmead Hospital, Bristol, UK
| | | | | | - Geoff Woodward
- Bristol Genetics Laboratory, Southmead Hospital, Bristol, UK
| | - Chris Buxton
- Bristol Genetics Laboratory, Southmead Hospital, Bristol, UK
| | - Gemma Dennis
- Bristol Genetics Laboratory, Southmead Hospital, Bristol, UK
| | - Gavin I Welsh
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
| | - Maggie Williams
- Bristol Genetics Laboratory, Southmead Hospital, Bristol, UK
| | - Moin A Saleem
- Bristol Renal, School of Clinical Sciences, University of Bristol, Bristol, UK
- Bristol Royal Hospital for Children, Bristol, UK
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32
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Li Y, Wang Y, He Q, Dang X, Cao Y, Wu X, Mo S, He X, Yi Z. Genetic mutational testing of Chinese children with familial hematuria with biopsy‑proven FSGS. Mol Med Rep 2017; 17:1513-1526. [PMID: 29138824 PMCID: PMC5780091 DOI: 10.3892/mmr.2017.8023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 08/31/2017] [Indexed: 12/27/2022] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) is a pathological lesion rather than a disease, with a diverse etiology. FSGS may result from genetic and non‑genetic factors. FSGS is considered a podocyte disease due to the fact that in the majority of patients with proven‑FSGS, the lesion results from defects in the podocyte structure or function. However, FSGS does not result exclusively from podocyte‑associated genes, however also from other genes including collagen IV‑associated genes. Patients who carry the collagen type IVA3 chain (COL4A3) or COL4A4 mutations usually exhibit Alport Syndrome (AS), thin basement membrane neuropathy or familial hematuria (FH). Previous studies revealed that long‑time persistent microscopic hematuria may lead to FSGS. A case of a family is presented here where affected individuals exhibited FH with FSGS‑proven, or chronic kidney disease. Renal biopsies were unhelpful and failed to demonstrate glomerular or basement membrane defects consistent with an inherited glomerulopathy, and therefore a possible underlying genetic cause for a unifying diagnosis was pursued. Genomic DNA of the siblings affected by FH with biopsy‑proven FSGS was analyzed, and their father was screened for 18 gene mutations associated with FSGS [nephrin, podocin, CD2 associated protein, phospholipase C ε, actinin α 4, transient receptor potential cation channel subfamily C member 6, inverted formin, FH2 and WH2 domain containing, Wilms tumor 1, LIM homeobox transcription factor 1 β, laminin subunit β 2, laminin subunit β 3, galactosida α, integrin subunit β 4, scavenger receptor class B member 2, coenzyme Q2, decaprenyl diphosphate synthase subunit 2, mitochondrially encoded tRNA leucine 1 (UUA/G; TRNL1) and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a like 1] using matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry technology. Then whole exome sequencing (WES) was performed in the two probands to ascertain whether there were other known or unknown gene mutations that segregated with the disease. Using mass array technology, a TRNL1 missense homozygous mutation (m. 3290T>C) was identified in the probands diagnosed with FH and manifested as FSGS on biopsy. In addition, a COL4A4 missense mutation c. 4195A>T (p. M1399L) in heterozygous pattern was identified using WES. None of these variants were detected in their father. In the present study, a mutation in TRNL1 (m. 3290T>C) was identified, which was the first reported variant associated with FSGS. The COL4A4 (c. 4195A>T) may co‑segregate with FSGS. Screening for COL4A mutations in familial FSGS patients is suggested in the present study. Genetic investigations of families with similar clinical phenotypes should be a priority for nephrologists. The combination of mass array technology and WES may improve the detection rate of genetic mutation with a high level of accuracy.
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Affiliation(s)
- Yongzhen Li
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Ying Wang
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Qingnan He
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiqiang Dang
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Yan Cao
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiaochuan Wu
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Shuanghong Mo
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Xiaoxie He
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
| | - Zhuwen Yi
- Division of Pediatric Nephrology, Children's Medical Center of The Second Xiangya Hospital, Central South University, Changsha, Hunan 410011, P.R. China
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Zhang H, Wang F, Liu X, Zhong X, Yao Y, Xiao H. Steroid-resistant nephrotic syndrome caused by co-inheritance of mutations at NPHS1 and ADCK4 genes in two Chinese siblings. Intractable Rare Dis Res 2017; 6:299-303. [PMID: 29259860 PMCID: PMC5735285 DOI: 10.5582/irdr.2017.01037] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Hereditary nephrotic syndrome often presents with steroid-resistance and onset within the first year of life. Mutations in genes highly expressed in podocytes have been found in two thirds of these patients, especially NPHS1 and NPHS2 among at least 29 genetic causes that have been discovered. We reported two siblings with steroid-resistant nephrotic syndrome caused by co-inheritance of mutations at NPHS1 (c.1339G>A, p.E447K) and ACDK4 (c.748G>C, p.D250H) genes. The siblings presented with steroid-resistant nephrotic syndrome and pathological lesions of focal segmental glomerulosclerosis (FSGS), while the elder sister also developed hypertension, renal failure and cardiac dysfunction.
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Affiliation(s)
- Hongwen Zhang
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Fang Wang
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Xiaoyu Liu
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Xuhui Zhong
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Yong Yao
- Department of Pediatric, Peking University First Hospital, Beijing, China
| | - Huijie Xiao
- Department of Pediatric, Peking University First Hospital, Beijing, China
- Address correspondence to: Dr. Huijie Xiao, Department of Pediatric, Peking University First Hospital, No.1 Xi An Men Da Jie, Beijing 100034, China. E-mail:
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34
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Three Novel Mutations in the NPHS1 Gene in Vietnamese Patients with Congenital Nephrotic Syndrome. Case Rep Genet 2017; 2017:2357282. [PMID: 28392951 PMCID: PMC5368377 DOI: 10.1155/2017/2357282] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Revised: 12/26/2016] [Accepted: 02/13/2017] [Indexed: 11/17/2022] Open
Abstract
Congenital nephrotic syndrome, a rare and severe disease, is inherited as an autosomal recessive trait. The disease manifests shortly after birth and occurs predominantly in families of Finnish origin but has now been observed in all countries and races. Mutations in the NPHS1 gene, which encodes nephrin, are the main causes of congenital nephrotic syndrome in patients. In this study, we report the first mutational analysis of the NPHS1 gene in three unrelated children from three different Vietnamese families. These patients were examined and determined to be suffering from congenital nephrotic syndrome in the Department of Pediatrics, Vietnam National Hospital of Pediatrics. All 29 exons and exon-intron boundaries of NPHS1 were analyzed by PCR and DNA sequencing. Genetic analysis of the NPHS1 gene revealed one compound heterozygous variant p.Glu117Lys, one heterozygous missense mutation p.Asp310Asn, and one heterozygous frame-shifting mutation (c.3250_3251insG causing p.Val1084Glyfs⁎12) in patient 1. In patient 2, one heterozygous variant p.Glu117Lys and one novel heterozygous missense mutation p.Ser324Ala were identified. Finally, a novel missense mutation p.Arg802Leu and a novel nonsense mutation (c.2442C>G causing p.K792⁎) were identified in patient 3.
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Ni J, Bao S, Johnson RI, Zhu B, Li J, Vadaparampil J, Smith CM, Campbell KN, Grahammer F, Huber TB, He JC, D'Agati VD, Chan A, Kaufman L. MAGI-1 Interacts with Nephrin to Maintain Slit Diaphragm Structure through Enhanced Rap1 Activation in Podocytes. J Biol Chem 2016; 291:24406-24417. [PMID: 27707879 PMCID: PMC5114397 DOI: 10.1074/jbc.m116.745026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/05/2016] [Indexed: 12/15/2022] Open
Abstract
MAGI-1 is a multidomain cytosolic scaffolding protein that in the kidney is specifically located at the podocyte slit diaphragm, a specialized junction that is universally injured in proteinuric diseases. There it interacts with several essential molecules, including nephrin and neph1, which are required for slit diaphragm formation and as an intracellular signaling hub. Here, we show that diminished MAGI-1 expression in cultured podocytes reduced nephrin and neph1 membrane localization and weakened tight junction integrity. Global magi1 knock-out mice, however, demonstrated normal glomerular histology and function into adulthood. We hypothesized that a second mild but complementary genetic insult might induce glomerular disease susceptibility in these mice. To identify such a gene, we utilized the developing fly eye to test for functional complementation between MAGI and its binding partners. In this way, we identified diminished expression of fly Hibris (nephrin) or Roughest (neph1) as dramatically exacerbating the effects of MAGI depletion. Indeed, when these combinations were studied in mice, the addition of nephrin, but not neph1, heterozygosity to homozygous deletion of MAGI-1 resulted in spontaneous glomerulosclerosis. In cultured podocytes, MAGI-1 depletion reduced intercellular contact-induced Rap1 activation, a pathway critical for proper podocyte function. Similarly, magi1 knock-out mice showed diminished glomerular Rap1 activation, an effect dramatically enhanced by concomitant nephrin haploinsufficiency. Finally, combined overexpression of MAGI-1 and nephrin increased Rap1 activation, but not when substituting a mutant MAGI-1 that cannot bind nephrin. We conclude that the interaction between nephrin and MAGI-1 regulates Rap1 activation in podocytes to maintain long term slit diaphragm structure.
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Affiliation(s)
- Jie Ni
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029,; the Division of Nephrology, First Affiliated Hospital of Harbin Medical University, Harbin, China 150001
| | - Sujin Bao
- the Saint James School of Medicine, Saint Vincent and the Grenadines
| | - Ruth I Johnson
- the Biology Department, Wesleyan University, Middletown, Connecticut, 06459
| | - Bingbing Zhu
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029,; the Department of Nephrology, Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China 200062
| | - Jianhua Li
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Justin Vadaparampil
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Christopher M Smith
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Kirk N Campbell
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Florian Grahammer
- the Department of Medicine IV, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany
| | - Tobias B Huber
- the Department of Medicine IV, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, 79106 Freiburg, Germany,; the BIOSS Center for Biological Signaling Studies, Albert-Ludwigs-University Freiburg, 79104 Freiburg, Germany,; FRIAS, Freiburg Institute for Advanced Studies and Center for Systems Biology (ZBSA), Albert-Ludwigs-University, 79104 Freiburg, Germany
| | - John C He
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Vivette D D'Agati
- the Department of Pathology, Columbia University Medical Center, New York, New York 10032, and
| | - Andrew Chan
- the School of Biomedical Sciences, Chinese University of Hong Kong, Hong Kong, China
| | - Lewis Kaufman
- From the Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York 10029,.
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Romagnani P, Giglio S, Angelotti ML, Provenzano A, Becherucci F, Mazzinghi B, Müller S, Amann K, Weidenbusch M, Romoli S, Lazzeri E, Anders HJ. Next generation sequencing and functional analysis of patient urine renal progenitor-derived podocytes to unravel the diagnosis underlying refractory lupus nephritis. Nephrol Dial Transplant 2016; 31:1541-5. [PMID: 27325253 DOI: 10.1093/ndt/gfw234] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Accepted: 05/16/2016] [Indexed: 11/13/2022] Open
Abstract
Often the cause of refractory lupus nephritis (RLN) remains unclear. We performed next-generation sequencing for podocyte genes in an RLN patient and identified compound heterozygosity for APOL1 risk alleles G1 and G2 and a novel homozygous c.[1049C>T]+[1049C>T] NPHS1 gene variant of unknown significance. To test for causality renal progenitor cells isolated from urine of this patient were differentiated into podocytes in vitro. Podocytes revealed aberrant nephrin trafficking, cytoskeletal structure and lysosomal leakage, and increased detachment as compared with podocytes isolated from controls. Thus, lupus podocytopathy can be confirmed as a cause of RLN by functional genetics on patient-derived podocytes.
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Affiliation(s)
- Paola Romagnani
- Department of Biomedical Experimental and Clinical Sciences 'Mario Serio', Florence, Italy Nephrology and Dialysis Unit, Meyer Children's University Hospital, Florence, Italy
| | - Sabrina Giglio
- Department of Biomedical Experimental and Clinical Sciences 'Mario Serio', Florence, Italy Medical Genetic Unit, Meyer Children's University Hospital, Florence, Italy
| | - Maria Lucia Angelotti
- Excellence Centre for Research, Transfer and High Education for the Development of De Novo Therapies (DENOTHE), University of Florence, Florence, Italy
| | - Aldesia Provenzano
- Medical Genetic Unit, Meyer Children's University Hospital, Florence, Italy
| | - Francesca Becherucci
- Nephrology and Dialysis Unit, Meyer Children's University Hospital, Florence, Italy
| | - Benedetta Mazzinghi
- Nephrology and Dialysis Unit, Meyer Children's University Hospital, Florence, Italy
| | - Susanna Müller
- Pathologisches Institut, Ludwig-Maximilians Universität, München, Germany
| | - Kerstin Amann
- Department of Nephropathology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Marc Weidenbusch
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Innenstadt, Munich, Germany
| | - Simone Romoli
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Innenstadt, Munich, Germany
| | - Elena Lazzeri
- Excellence Centre for Research, Transfer and High Education for the Development of De Novo Therapies (DENOTHE), University of Florence, Florence, Italy
| | - Hans-Joachim Anders
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der LMU München, Innenstadt, Munich, Germany
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37
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Sampson MG, Pollak MR. Opportunities and Challenges of Genotyping Patients With Nephrotic Syndrome in the Genomic Era. Semin Nephrol 2016. [PMID: 26215859 DOI: 10.1016/j.semnephrol.2015.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Both targeted and genome-wide linkage and association studies have identified a number of genes and genetic variants associated with nephrotic syndrome (NS). Genotype-phenotype studies of patients with these variants have identified correlations of clear clinical significance. Combined with improved genomic technologies, this has resulted in increasing, and justifiable, enthusiasm for incorporating our patients' genomic information into our clinical management decisions. Here, we summarize our understanding of NS-associated genetic factors, namely rare causal mutations or common risk alleles in apolipoprotein L1. We discuss the complexities inherent in trying to ascribe risk or causality to these variants, particularly as we seek to extend genetic testing to a broader group of patients, including many with sporadic disease. Overall, the thoughtful application and interpretation of these genetic tests will maximize the benefits to our patients with NS in the form of more precise clinical care.
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Affiliation(s)
- Matthew G Sampson
- Department of Pediatrics, Division of Nephrology, University of Michigan School of Medicine, Ann Arbor, MI.
| | - Martin R Pollak
- Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA
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38
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Chen YM, Liapis H. Focal segmental glomerulosclerosis: molecular genetics and targeted therapies. BMC Nephrol 2015; 16:101. [PMID: 26156092 PMCID: PMC4496884 DOI: 10.1186/s12882-015-0090-9] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 06/16/2015] [Indexed: 12/18/2022] Open
Abstract
Recent advances show that human focal segmental glomerulosclerosis (FSGS) is a primary podocytopathy caused by podocyte-specific gene mutations including NPHS1, NPHS2, WT-1, LAMB2, CD2AP, TRPC6, ACTN4 and INF2. This review focuses on genes discovered in the investigation of complex FSGS pathomechanisms that may have implications for the current FSGS classification scheme. It also recounts recent recommendations for clinical management of FSGS based on translational studies and clinical trials. The advent of next-generation sequencing promises to provide nephrologists with rapid and novel approaches for the diagnosis and treatment of FSGS. A stratified and targeted approach based on the underlying molecular defects is evolving.
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Affiliation(s)
- Ying Maggie Chen
- Renal Division, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO, 63110, USA.
| | - Helen Liapis
- , Nephropath, Little Rock, Arkansas
- Pathology & Immunology, Washington University School of Medicine, St. Louis, MO, USA
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39
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Pharmacological targeting of actin-dependent dynamin oligomerization ameliorates chronic kidney disease in diverse animal models. Nat Med 2015; 21:601-9. [PMID: 25962121 PMCID: PMC4458177 DOI: 10.1038/nm.3843] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 03/18/2015] [Indexed: 12/11/2022]
Abstract
Dysregulation of the actin cytoskeleton in podocytes represents a common pathway in the pathogenesis of proteinuria across a spectrum of chronic kidney diseases (CKD). The GTPase dynamin has been implicated in the maintenance of cellular architecture in podocytes through its direct interaction with actin. Furthermore, the propensity of dynamin to oligomerize into higher-order structures in an actin-dependent manner and to crosslink actin microfilaments into higher order structures have been correlated with increased actin polymerization and global organization of the actin cytoskeleton in the cell. We found that use of the small molecule Bis-T-23, which promotes actin-dependent dynamin oligomerization and thus increased actin polymerization in injured podocytes, was sufficient to improve renal health in diverse models of both transient kidney disease and of CKD. In particular, administration of Bis-T-23 in these renal disease models restored the normal ultrastructure of podocyte foot processes, lowered proteinuria, lowered collagen IV deposits in the mesangial matrix, diminished mesangial matrix expansion and extended lifespan. These results further establish that alterations in the actin cytoskeleton of kidney podocytes is a common hallmark of CKD, while also underscoring the significant regenerative potential of injured glomeruli and that targeting the oligomerization cycle of dynamin represents an attractive potential therapeutic target to treat CKD.
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40
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Genetic causes of proteinuria and nephrotic syndrome: impact on podocyte pathobiology. Pediatr Nephrol 2015; 30:221-33. [PMID: 24584664 PMCID: PMC4262721 DOI: 10.1007/s00467-014-2753-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 12/31/2013] [Accepted: 01/02/2014] [Indexed: 12/11/2022]
Abstract
In the past 20 years, multiple genetic mutations have been identified in patients with congenital nephrotic syndrome (CNS) and both familial and sporadic focal segmental glomerulosclerosis (FSGS). Characterization of the genetic basis of CNS and FSGS has led to the recognition of the importance of podocyte injury to the development of glomerulosclerosis. Genetic mutations induce injury due to effects on the podocyte's structure, actin cytoskeleton, calcium signaling, and lysosomal and mitochondrial function. Transgenic animal studies have contributed to our understanding of podocyte pathobiology. Podocyte endoplasmic reticulum stress response, cell polarity, and autophagy play a role in maintenance of podocyte health. Further investigations related to the effects of genetic mutations on podocytes may identify new pathways for targeting therapeutics for nephrotic syndrome.
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41
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Bińczak-Kuleta A, Rubik J, Litwin M, Ryder M, Lewandowska K, Taryma-Leśniak O, Clark JS, Grenda R, Ciechanowicz A. Retrospective mutational analysis of NPHS1, NPHS2, WT1 and LAMB2 in children with steroid-resistant focal segmental glomerulosclerosis - a single-centre experience. Bosn J Basic Med Sci 2015; 14:89-93. [PMID: 24856380 DOI: 10.17305/bjbms.2014.2270] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
The aim of our study was to examine NPHS1, NPHS2, WT1 and LAMB2 mutations, previously reported in two thirds of patients with nephrotic syndrome with onset before the age of one year old. Genomic DNA samples from Polish children (n=33) with Steroid-Resistant Nephrotic Syndrome (SRNS) due to focal segmental glomerulosclerosis (FSGS), manifesting before the age of 13 years old, underwent retrospective analysis of NPHS1, NPHS2, WT1 (exons 8, 9 and adjacent exon/intron boundaries) and LAMB2. No pathogenic NPHS1 or LAMB2 mutations were found in our FSGS cohort. SRNS-causing mutations of NPHS2 and WT1 were detected in 7 of 33 patients (21%), including those with nephrotic syndrome manifesting before one year old: five of seven patients. Four patients had homozygous c.413G>A (p.Arg138Gln) NPHS2 mutations; one subject was homozygous for c.868G>A (p.Val290Met) NPHS2. A phenotypic female had C>T transition at position +4 of the WT1 intron 9 (c.1432+4C>T) splice-donor site, and another phenotypic female was heterozygous for G>A transition at position +5 (c.1432+5G>A). Genotyping revealed a female genotypic gender (46, XX) for the first subject and male (46, XY) for the latter. In addition, one patient was heterozygous for c.104dup (p.Arg36Profs*34) NPHS2; two patients carried a c.686G>A (p.Arg229Gln) NPHS2 non-neutral variant. Results indicate possible clustering of causative NPHS2 mutations in FSGS-proven SRNS with onset before age one year old, and provide additional evidence that patients with childhood steroid-resistant nephrotic syndrome due to focal segmental glomerulosclerosis should first undergo analysis of NPHS2 coding sequence and WT1 exons 8 and 9 and surrounding exon/intron boundary sequences, followed by gender genotyping.
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Affiliation(s)
- Agnieszka Bińczak-Kuleta
- Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, al. Powstańców Wlkp. 72, 70-111 Szczecin, Poland
| | - Jacek Rubik
- Department of Nephrology, Kidney Transplantation and Hypertension, Children`s Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland
| | - Mieczysław Litwin
- Department of Nephrology, Kidney Transplantation and Hypertension, Children`s Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland
| | - Małgorzata Ryder
- Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, al. Powstańców Wlkp. 72, 70-111 Szczecin, Poland
| | - Klaudyna Lewandowska
- Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, al. Powstańców Wlkp. 72, 70-111 Szczecin, Poland
| | - Olga Taryma-Leśniak
- Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, al. Powstańców Wlkp. 72, 70-111 Szczecin, Poland
| | - Jeremy S Clark
- Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, al. Powstańców Wlkp. 72, 70-111 Szczecin, Poland
| | - Ryszard Grenda
- Department of Nephrology, Kidney Transplantation and Hypertension, Children`s Memorial Health Institute, Al. Dzieci Polskich 20, 04-730 Warsaw, Poland
| | - Andrzej Ciechanowicz
- Department of Clinical and Molecular Biochemistry, Pomeranian Medical University, al. Powstańców Wlkp. 72, 70-111 Szczecin, Poland
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Slavotinek A, Kaylor J, Pierce H, Cahr M, DeWard S, Schneidman-Duhovny D, Alsadah A, Salem F, Schmajuk G, Mehta L. CRB2 mutations produce a phenotype resembling congenital nephrosis, Finnish type, with cerebral ventriculomegaly and raised alpha-fetoprotein. Am J Hum Genet 2015; 96:162-9. [PMID: 25557780 DOI: 10.1016/j.ajhg.2014.11.013] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 11/21/2014] [Indexed: 12/17/2022] Open
Abstract
We report five fetuses and a child from three families who shared a phenotype comprising cerebral ventriculomegaly and echogenic kidneys with histopathological findings of congenital nephrosis. The presenting features were greatly elevated maternal serum alpha-fetoprotein (MSAFP) or amniotic fluid alpha-fetoprotein (AFAFP) levels or abnormalities visualized on ultrasound scan during the second trimester of pregnancy. Exome sequencing revealed deleterious sequence variants in Crumbs, Drosophila, Homolog of, 2 (CRB2) consistent with autosomal-recessive inheritance. Two fetuses with cerebral ventriculomegaly and renal microcysts were compound heterozygotes for p.Asn800Lys and p.Trp759Ter, one fetus with renal microcysts was a compound heterozygote for p.Glu643Ala and p.Asn800Lys, and one child with cerebral ventriculomegaly, periventricular heterotopias, echogenic kidneys, and renal failure was homozygous for p.Arg633Trp in CRB2. Examination of the kidneys in one fetus showed tubular cysts at the corticomedullary junction and diffuse effacement of the epithelial foot processes and microvillous transformation of the renal podocytes, findings that were similar to those reported in congenital nephrotic syndrome, Finnish type, that is caused by mutations in nephrin (NPHS1). Loss of function for crb2b and nphs1 in Danio rerio were previously shown to result in loss of the slit diaphragms of the podocytes, leading to the hypothesis that nephrosis develops from an inability to develop a functional glomerular barrier. We conclude that the phenotype associated with CRB2 mutations is pleiotropic and that the condition is an important consideration in the evaluation of high MSAFP/AFAFP where a renal cause is suspected.
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43
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Bullich G, Trujillano D, Santín S, Ossowski S, Mendizábal S, Fraga G, Madrid Á, Ariceta G, Ballarín J, Torra R, Estivill X, Ars E. Targeted next-generation sequencing in steroid-resistant nephrotic syndrome: mutations in multiple glomerular genes may influence disease severity. Eur J Hum Genet 2014; 23:1192-9. [PMID: 25407002 PMCID: PMC4538209 DOI: 10.1038/ejhg.2014.252] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2014] [Revised: 10/14/2014] [Accepted: 10/16/2014] [Indexed: 01/26/2023] Open
Abstract
Genetic diagnosis of steroid-resistant nephrotic syndrome (SRNS) using Sanger sequencing is complicated by the high genetic heterogeneity and phenotypic variability of this disease. We aimed to improve the genetic diagnosis of SRNS by simultaneously sequencing 26 glomerular genes using massive parallel sequencing and to study whether mutations in multiple genes increase disease severity. High-throughput mutation analysis was performed in 50 SRNS and/or focal segmental glomerulosclerosis (FSGS) patients, a validation cohort of 25 patients with known pathogenic mutations, and a discovery cohort of 25 uncharacterized patients with probable genetic etiology. In the validation cohort, we identified the 42 previously known pathogenic mutations across NPHS1, NPHS2, WT1, TRPC6, and INF2 genes. In the discovery cohort, disease-causing mutations in SRNS/FSGS genes were found in nine patients. We detected three patients with mutations in an SRNS/FSGS gene and COL4A3. Two of them were familial cases and presented a more severe phenotype than family members with mutation in only one gene. In conclusion, our results show that massive parallel sequencing is feasible and robust for genetic diagnosis of SRNS/FSGS. Our results indicate that patients carrying mutations in an SRNS/FSGS gene and also in COL4A3 gene have increased disease severity.
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Affiliation(s)
- Gemma Bullich
- 1] Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain [2] Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Daniel Trujillano
- 1] Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Catalonia, Spain [2] Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain [3] Hospital del Mar Medical Research Institute (IMIM), Barcelona, Catalonia, Spain [4] CIBER in Epidemiology and Public Health (CIBERESP), Barcelona, Catalonia, Spain
| | - Sheila Santín
- Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Stephan Ossowski
- 1] Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain [2] Genomic and Epigenomic Variation in Disease Group, Centre for Genomic Regulation (CRG), Barcelona, Catalonia, Spain
| | - Santiago Mendizábal
- Pediatric Nephrology Department, Hospital Universitario La Fe, Valencia, Spain
| | - Gloria Fraga
- Pediatric Nephrology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, Catalonia, Spain
| | - Álvaro Madrid
- Pediatric Nephrology Department, Hospital Vall d'Hebron, Barcelona, Spain
| | - Gema Ariceta
- Pediatric Nephrology Department, Hospital Vall d'Hebron, Barcelona, Spain
| | - José Ballarín
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Roser Torra
- Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
| | - Xavier Estivill
- 1] Genomics and Disease Group, Bioinformatics and Genomics Programme, Centre for Genomic Regulation (CRG), Barcelona, Catalonia, Spain [2] Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Catalonia, Spain [3] Hospital del Mar Medical Research Institute (IMIM), Barcelona, Catalonia, Spain [4] CIBER in Epidemiology and Public Health (CIBERESP), Barcelona, Catalonia, Spain
| | - Elisabet Ars
- 1] Molecular Biology Laboratory, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain [2] Nephrology Department, Fundació Puigvert, Instituto de Investigaciones Biomédicas Sant Pau (IIB-Sant Pau), Universitat Autònoma de Barcelona, REDinREN, Instituto de Investigación Carlos III, Barcelona, Catalonia, Spain
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44
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Pollak MR. Familial FSGS. Adv Chronic Kidney Dis 2014; 21:422-5. [PMID: 25168831 DOI: 10.1053/j.ackd.2014.06.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Revised: 05/31/2014] [Accepted: 06/02/2014] [Indexed: 12/12/2022]
Abstract
Focal segmental glomerulosclerosis (FSGS) and nephrotic syndrome can be caused by rare highly penetrant mutations in number of genes. FSGS can follow both recessive and dominant inheritance patterns. In general, recessive forms present early, whereas the autosomal dominant forms present in adolescence or adulthood. Many of the genes found to be mutated in FSGS and nephrotic syndrome patients encode proteins essential for normal podocyte structure and/or function. An exception appears to be APOL1, which harbors common variants responsible for the high rate of FSGS and other nephropathies in people of recent African ancestry. Familial FSGS should be regarded as part of a spectrum of inherited glomerulopathies where the precise histologic presentation may depend on the age of onset, function of the responsible gene and gene products, and other factors.
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45
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Abstract
Glomerular disorders in infancy can include nephrotic and nephritic syndromes. Congenital nephrotic syndrome (CNS) is most commonly caused by single gene mutations in kidney proteins, but may also be due to congenital infections or passive transfer of maternal antibodies that target kidney proteins. Prenatal findings of increased maternal serum α-fetoprotein and enlarged placenta suggest CNS. Neonatal nephritis is rare; its causes may overlap with those of CNS and include primary glomerulonephritis, systemic disease, infections, and transplacental transfer of maternal antibodies. These syndromes in the neonate can cause significant morbidity and mortality, making urgent diagnosis and treatment necessary.
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Affiliation(s)
- Michelle N Rheault
- Division of Pediatric Nephrology, University of Minnesota Children's Hospital, 2450 Riverside Avenue, MB680, Minneapolis, MN 55454, USA.
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46
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Hall G, Gbadegesin RA, Lavin P, Wu G, Liu Y, Oh EC, Wang L, Spurney RF, Eckel J, Lindsey T, Homstad A, Malone AF, Phelan PJ, Shaw A, Howell DN, Conlon PJ, Katsanis N, Winn MP. A novel missense mutation of Wilms' Tumor 1 causes autosomal dominant FSGS. J Am Soc Nephrol 2014; 26:831-43. [PMID: 25145932 DOI: 10.1681/asn.2013101053] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
FSGS is a clinical disorder characterized by focal scarring of the glomerular capillary tuft, podocyte injury, and nephrotic syndrome. Although idiopathic forms of FSGS predominate, recent insights into the molecular and genetic causes of FSGS have enhanced our understanding of disease pathogenesis. Here, we report a novel missense mutation of the transcriptional regulator Wilms' Tumor 1 (WT1) as the cause of nonsyndromic, autosomal dominant FSGS in two Northern European kindreds from the United States. We performed sequential genome-wide linkage analysis and whole-exome sequencing to evaluate participants from family DUK6524. Subsequently, whole-exome sequencing and direct sequencing were performed on proband DNA from family DUK6975. We identified multiple suggestive loci on chromosomes 6, 11, and 13 in family DUK6524 and identified a segregating missense mutation (R458Q) in WT1 isoform D as the cause of FSGS in this family. The identical mutation was found in family DUK6975. The R458Q mutation was not found in 1600 control chromosomes and was predicted as damaging by in silico simulation. We depleted wt1a in zebrafish embryos and observed glomerular injury and filtration defects, both of which were rescued with wild-type but not mutant human WT1D mRNA. Finally, we explored the subcellular mechanism of the mutation in vitro. WT1(R458Q) overexpression significantly downregulated nephrin and synaptopodin expression, promoted apoptosis in HEK293 cells and impaired focal contact formation in podocytes. Taken together, these data suggest that the WT1(R458Q) mutation alters the regulation of podocyte homeostasis and causes nonsyndromic FSGS.
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Affiliation(s)
- Gentzon Hall
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute
| | | | - Peter Lavin
- Department of Transplant, Urology and Nephrology, Beaumont Hospital, Dublin, Ireland
| | | | - Yangfan Liu
- Cell Biology, Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Edwin C Oh
- Cell Biology, Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | | | | | - Jason Eckel
- Division of Nephrology, Departments of Medicine
| | | | | | - Andrew F Malone
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute
| | - Paul J Phelan
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute
| | - Andrey Shaw
- Department of Pathology and Immunology, Washington University School of Medicine in St. Louis, St. Louis, Missouri; and
| | | | - Peter J Conlon
- Department of Transplant, Urology and Nephrology, Beaumont Hospital, Dublin, Ireland
| | - Nicholas Katsanis
- Departments of Medicine, Cell Biology, Center for Human Disease Modeling, Duke University Medical Center, Durham, North Carolina
| | - Michelle P Winn
- Division of Nephrology, Departments of Medicine, Duke Molecular Physiology Institute,
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Novel and known nephrin gene (NPHS1) mutations in two Greek cases with congenital nephrotic syndrome including a complex genotype. J Genet 2014; 92:577-81. [PMID: 24371179 DOI: 10.1007/s12041-013-0290-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Bonomo JA, Ng MCY, Palmer ND, Keaton JM, Larsen CP, Hicks PJ, Langefeld CD, Freedman BI, Bowden DW. Coding variants in nephrin (NPHS1) and susceptibility to nephropathy in African Americans. Clin J Am Soc Nephrol 2014; 9:1434-40. [PMID: 24948143 DOI: 10.2215/cjn.00290114] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
BACKGROUND AND OBJECTIVES Presumed genetic risk for diabetic and nondiabetic end stage renal disease is strong in African Americans. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Exome sequencing data from African Americans with type 2 diabetic end stage renal disease and nondiabetic, non-nephropathy controls in the T2D-GENES study (Discovery, n=529 patients and n=535 controls) were evaluated, focusing on missense variants in NPHS1. Associated variants were then evaluated in independent type 2 diabetic end stage renal disease (Replication, n=1305 patients and n=760 controls), nondiabetic end stage renal disease (n=1705), and type 2 diabetes-only, non-nephropathy samples (n=503). All participants were recruited from dialysis facilities and internal medicine clinics across the southeastern United States from 1991 to present. Additional NPHS1 missense variants were identified from exome sequencing resources, genotyped, and sequence kernel association testing was then performed. RESULTS Initial analysis identified rs35238405 (T233A; minor allele frequency=0.0096) as associated with type 2 diabetic end stage renal disease (adjustment for admixture P=0.042; adjustment for admixture+APOL1 P=0.080; odds ratio, 2.89 and 2.36, respectively); with replication in independent type 2 diabetic end stage renal disease samples (P=0.018; odds ratio, 4.30) and nondiabetic end stage renal disease samples (P=0.016; odds ratio, 4.48). In a combined analysis (all patients with end stage renal disease versus all controls), T233A was associated with all-cause end stage renal disease (P=0.0038; odds ratio, 2.82; n=3270 patients and n=1187 controls). A P-value of <0.001 was obtained after adjustment for admixture and APOL1 in sequence kernel association testing. Two additional variants (H800R and Y1174H) were nominally associated with protection from end stage renal disease (P=0.036; odds ratio, 0.44; P=0.0084; odds ratio, 0.040, respectively) in the locus-wide single-variant association tests. CONCLUSIONS Coding variants in NPHS1 are associated with both risk for and protection from common forms of nephropathy in African Americans.
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Affiliation(s)
- Jason A Bonomo
- Departments of Molecular Medicine and Translational Science, Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and
| | - Maggie C Y Ng
- Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and Biochemistry
| | - Nicholette D Palmer
- Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and Biochemistry
| | - Jacob M Keaton
- Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and
| | | | - Pamela J Hicks
- Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and
| | | | - Carl D Langefeld
- Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and Biostatistical Sciences, and
| | | | - Donald W Bowden
- Center for Human Genomics and Personalized Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina; and Biochemistry,
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Brown EJ, Pollak MR, Barua M. Genetic testing for nephrotic syndrome and FSGS in the era of next-generation sequencing. Kidney Int 2014; 85:1030-8. [PMID: 24599252 PMCID: PMC4118212 DOI: 10.1038/ki.2014.48] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Revised: 01/07/2014] [Accepted: 01/09/2014] [Indexed: 12/11/2022]
Abstract
The haploid human genome is composed of three billion base pairs, about one percent of which consists of exonic regions, the coding sequence for functional proteins, also now known as the “exome”. The development of next-generation sequencing makes it possible from a technical and economic standpoint to sequence an individual’s exome but at the cost of generating long lists of gene variants that are not straightforward to interpret. Various public consortiums such as the 1000 Genomes Project and the NHLBI Exome Sequencing Project have sequenced the exomes and a subset of entire genomes of over 2500 control individuals with ongoing efforts to further catalogue genetic variation in humans.1 The use of these public databases facilitates the interpretation of these variant lists produced by exome sequencing and, as a result, novel genetic variants linked to disease are being discovered and reported at a record rate. However, the interpretation of these results and their bearing on diagnosis, prognosis, and treatment is becoming ever more complicated. Here, we discuss the application of genetic testing to individuals with focal and segmental glomerulosclerosis (FSGS), taking a historical perspective on gene identification and its clinical implications along with the growing potential of next-generation sequencing.
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Affiliation(s)
- Elizabeth J Brown
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Martin R Pollak
- Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | - Moumita Barua
- 1] Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA [2] Department of Medicine, Toronto General Hospital, Toronto, Ontario, Canada
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50
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Sethi S, Glassock RJ, Fervenza FC. Focal segmental glomerulosclerosis: towards a better understanding for the practicing nephrologist. Nephrol Dial Transplant 2014; 30:375-84. [PMID: 24589721 DOI: 10.1093/ndt/gfu035] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Focal and segmental glomerulosclerosis (FSGS) is a common histopathological lesion that can represent a primary podocytopathy, or occur as an adaptive phenomenon consequent to nephron mass reduction, a scar from a healing vasculitic lesion, direct drug toxicity or viral infection among other secondary causes. Thus, the presence of an FSGS lesion in a renal biopsy does not confer a disease diagnosis, but rather represents the beginning of an exploratory process, hopefully leading ultimately to identification of a specific etiology and its appropriate treatment. We define primary FSGS as a 'primary' podocytopathy characterized clinically by the presence of nephrotic syndrome in a patient with an FSGS lesion on light microscopy and widespread foot process effacement on electron microscopy (EM). Secondary FSGS is commonly characterized by the absence of nephrotic syndrome and the presence of segmental foot process effacement on EM. Failure to accurately differentiate between the primary and secondary forms of FSGS has resulted in many patients undergoing unnecessary immunosuppressive treatment. Here, we review some key points that may assist the practicing nephrologist to distinguish between primary and secondary FSGS.
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Affiliation(s)
- Sanjeev Sethi
- Division of Anatomic Pathology, Mayo Clinic College of Medicine, Rochester, MN, USA
| | | | - Fernando C Fervenza
- Division of Nephrology and Hypertension, Mayo Clinic College of Medicine, Rochester, MN, USA
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