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Bonilla M, Efe O, Selvaskandan H, Lerma EV, Wiegley N. A Review of Focal Segmental Glomerulosclerosis Classification With a Focus on Genetic Associations. Kidney Med 2024; 6:100826. [PMID: 38765809 PMCID: PMC11099322 DOI: 10.1016/j.xkme.2024.100826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/22/2024] Open
Abstract
Focal segmental glomerulosclerosis (FSGS) defines a distinct histologic pattern observed in kidney tissue that is linked to several distinct underlying causes, all converging on the common factor of podocyte injury. It presents a considerable challenge in terms of classification because of its varied underlying causes and the limited correlation between histopathology and clinical outcomes. Critically, precise nomenclature is key to describe and delineate the pathogenesis, subsequently guiding the selection of suitable and precision therapies. A proposed pathomechanism-based approach has been suggested for FSGS classification. This approach differentiates among primary, secondary, genetic, and undetermined causes, aiming to provide clarity. Genetic FSGS from monogenic mutations can emerge during childhood or adulthood, and it is advisable to conduct genetic testing in cases in which there is a family history of chronic kidney disease, nephrotic syndrome, or resistance to treatment. Genome-wide association studies have identified several genetic risk variants, such as those in apolipoprotein L1 (APOL1), that play a role in the development of FSGS. Currently, no specific treatments have been approved to treat genetic FSGS; however, interventions targeting underlying cofactor deficiencies have shown potential in some cases. Furthermore, encouraging results have emerged from a phase 2 trial investigating inaxaplin, a novel small molecule APOL1 channel inhibitor, in APOL1-associated FSGS.
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Affiliation(s)
- Marco Bonilla
- Section of Nephrology, Department of Medicine, University of Chicago, Chicago, IL
| | - Orhan Efe
- Division of Nephrology, Massachusetts General Hospital, Boston, MA
- Harvard Medical School, Boston, MA
| | - Haresh Selvaskandan
- IgA Mayer Nephropathy Laboratories, Department of Cardiovascular Sciences, University of Leicester, Leicester, United Kingdom
- John Walls Renal Unit, University Hospitals of Leicester NHS Trust, Leicester, United Kingdom
| | - Edgar V. Lerma
- Section of Nephrology, University of Illinois at Chicago/Advocate Christ Medical Center, Oak Lawn, IL
| | - Nasim Wiegley
- University of California Davis School of Medicine, Division of Nephrology, Sacramento, CA
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2
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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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3
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Mirioglu S, Daniel-Fischer L, Berke I, Ahmad SH, Bajema IM, Bruchfeld A, Fernandez-Juarez GM, Floege J, Frangou E, Goumenos D, Griffith M, Moran SM, van Kooten C, Steiger S, Stevens KI, Turkmen K, Willcocks LC, Kronbichler A. Management of adult patients with podocytopathies: an update from the ERA Immunonephrology Working Group. Nephrol Dial Transplant 2024; 39:569-580. [PMID: 38341276 PMCID: PMC11024823 DOI: 10.1093/ndt/gfae025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Indexed: 02/12/2024] Open
Abstract
The histopathological lesions, minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) are entities without immune complex deposits which can cause podocyte injury, thus are frequently grouped under the umbrella of podocytopathies. Whether MCD and FSGS may represent a spectrum of the same disease remains a matter of conjecture. Both frequently require repeated high-dose glucocorticoid therapy with alternative immunosuppressive treatments reserved for relapsing or resistant cases and response rates are variable. There is an unmet need to identify patients who should receive immunosuppressive therapies as opposed to those who would benefit from supportive strategies. Therapeutic trials focusing on MCD are scarce, and the evidence used for the 2021 Kidney Disease: Improving Global Outcomes (KDIGO) guideline for the management of glomerular diseases largely stems from observational and pediatric trials. In FSGS, the differentiation between primary forms and those with underlying genetic variants or secondary forms further complicates trial design. This article provides a perspective of the Immunonephrology Working Group (IWG) of the European Renal Association (ERA) and discusses the KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases focusing on the management of MCD and primary forms of FSGS in the context of recently published evidence, with a special emphasis on the role of rituximab, cyclophosphamide, supportive treatment options and ongoing clinical trials in the field.
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Affiliation(s)
- Safak Mirioglu
- Division of Nephrology, Bezmialem Vakif University School of Medicine, Istanbul, Turkey
- Department of Immunology, Aziz Sancar Institute of Experimental Medicine, Istanbul University, Istanbul, Turkey
| | - Lisa Daniel-Fischer
- Division of Pediatric Nephrology and Gastroenterology, Department of Pediatrics and Adolescent Medicine, Comprehensive Center for Pediatrics, Medical University of Vienna, Vienna, Austria
| | - Ilay Berke
- Division of Nephrology, Marmara University School of Medicine, Istanbul, Turkey
| | - Syed Hasan Ahmad
- Department of Renal Medicine, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
| | - Ingeborg M Bajema
- Department of Pathology and Medical Biology, University of Groningen, University Medical Center Groningen, The Netherlands
| | - Annette Bruchfeld
- Department of Health, Medicine and Caring Sciences, Linköping University, Linköping, Sweden
- Department of Renal Medicine, Karolinska University Hospital and CLINTEC Karolinska Institutet, Stockholm, Sweden
| | | | - Jürgen Floege
- Division of Nephrology, RWTH Aachen University Hospital, Aachen, Germany
| | - Eleni Frangou
- Department of Nephrology, Limassol General Hospital, Limassol, Cyprus; University of Nicosia Medical School, Nicosia, Cyprus
| | - Dimitrios Goumenos
- Department of Nephrology and Renal Transplantation, Patras University Hospital, Patras, Greece
| | - Megan Griffith
- Imperial College Healthcare NHS Trust Renal and Transplant Centre, Hammersmith Hospital, London, United Kingdom
| | - Sarah M Moran
- Cork University Hospital, University College Cork, Cork, Ireland
| | - Cees van Kooten
- Division of Nephrology and Transplant Medicine, Department of Medicine, Leiden University Medical Center, Leiden, The Netherlands
| | - Stefanie Steiger
- Division of Nephrology, Department of Internal Medicine IV, Hospital of the Ludwig-Maximilians-University, Munich, Germany
| | - Kate I Stevens
- Glasgow Renal and Transplant Unit, Queen Elizabeth University Hospital, Glasgow, UK
| | - Kultigin Turkmen
- Division of Nephrology, Department of Internal Medicine, Necmettin Erbakan University, Konya, Turkey
| | - Lisa C Willcocks
- Department of Renal Medicine, Addenbrooke's Hospital, Cambridge University Hospitals, Cambridge, UK
| | - Andreas Kronbichler
- Department of Internal Medicine IV, Nephrology and Hypertension, Medical University Innsbruck, Innsbruck, Austria
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Shirai Y, Miura K, Ishizuka K, Ando T, Kanda S, Hashimoto J, Hamasaki Y, Hotta K, Ito N, Honda K, Tanabe K, Takano T, Hattori M. A multi-institutional study found a possible role of anti-nephrin antibodies in post-transplant focal segmental glomerulosclerosis recurrence. Kidney Int 2024; 105:608-617. [PMID: 38110152 DOI: 10.1016/j.kint.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 11/07/2023] [Accepted: 11/10/2023] [Indexed: 12/20/2023]
Abstract
Possible roles of anti-nephrin antibodies in post-transplant recurrent focal segmental glomerulosclerosis (FSGS) have been reported recently. To confirm these preliminary results, we performed a multi-institutional study of 22 Japanese pediatric kidney transplant recipients with FSGS including eight genetic FSGS and 14 non-genetic (presumed primary) FSGS. Eleven of the 14 non-genetic FSGS patients had post-transplant recurrent FSGS. Median (interquartile range) plasma levels of anti-nephrin antibodies in post-transplant recurrent FSGS measured using ELISA were markedly high at 899 (831, 1292) U/mL (cutoff 231 U/mL) before transplantation or during recurrence. Graft biopsies during recurrence showed punctate IgG deposition co-localized with nephrin that had altered localization with increased nephrin tyrosine phosphorylation and Src homology and collagen homology A expressions. Graft biopsies after remission showed no signals for IgG and a normal expression pattern of nephrin. Anti-nephrin antibody levels decreased to 155 (53, 367) U/mL in five patients with samples available after remission. In patients with genetic FSGS as in those with non-genetic FSGS without recurrence, anti-nephrin antibody levels were comparable to those of 30 control individuals, and graft biopsies had no signals for IgG and a normal expression pattern of nephrin. Thus, our results suggest that circulating anti-nephrin antibodies are a possible candidate for circulating factors involved in the pathogenesis of post-transplant recurrent FSGS and that this may be mediated by nephrin phosphorylation. Larger studies including other ethnicities are required to confirm this finding.
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Affiliation(s)
- Yoko Shirai
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | - Kenichiro Miura
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | - Kiyonobu Ishizuka
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | - Taro Ando
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan
| | | | - Junya Hashimoto
- Department of Nephrology, Toho University Faculty of Medicine, Tokyo, Japan
| | - Yuko Hamasaki
- Department of Nephrology, Toho University Faculty of Medicine, Tokyo, Japan
| | - Kiyohiko Hotta
- Department of Urology, Hokkaido University, Graduate School of Medicine, Hokkaido, Japan
| | - Naoko Ito
- Department of Surgical Pathology, Tokyo Women's Medical University, Tokyo, Japan
| | - Kazuho Honda
- Department of Anatomy, Showa University School of Medicine, Tokyo, Japan
| | - Kenji Tanabe
- Medical Research Institute, Tokyo Women's Medical University, Tokyo, Japan
| | - Tomoko Takano
- Division of Nephrology, McGill University Health Centre, Montreal, Québec, Canada
| | - Motoshi Hattori
- Department of Pediatric Nephrology, Tokyo Women's Medical University, Tokyo, Japan.
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Tato AM, Carrera N, García-Murias M, Shabaka A, Ávila A, Mora Mora MT, Rabasco C, Soto K, de la Prada Alvarez FJ, Fernández-Lorente L, Rodríguez-Moreno A, Huerta A, Mon C, García-Carro C, González Cabrera F, Navarro JAM, Romera A, Gutiérrez E, Villacorta J, de Lorenzo A, Avilés B, Garca-González MA, Fernández-Juárez G. Genetic testing in focal segmental glomerulosclerosis: in whom and when? Clin Kidney J 2023; 16:2011-2022. [PMID: 37915894 PMCID: PMC10616495 DOI: 10.1093/ckj/sfad193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Indexed: 11/03/2023] Open
Abstract
Background Genetic causes are increasingly recognized in patients with focal segmental glomerulosclerosis (FSGS), but it remains unclear which patients should undergo genetic study. Our objective was to determine the frequency and distribution of genetic variants in steroid-resistant nephrotic syndrome FSGS (SRNS-FSGS) and in FSGS of undetermined cause (FSGS-UC). Methods We performed targeted exome sequencing of 84 genes associated with glomerulopathy in patients with adult-onset SRNS-FSGS or FSGS-UC after ruling out secondary causes. Results Seventy-six patients met the study criteria; 24 presented with SRNS-FSGS and 52 with FSGS-UC. We detected FSGS-related disease-causing variants in 27/76 patients (35.5%). There were no differences between genetic and non-genetic causes in age, proteinuria, glomerular filtration rate, serum albumin, body mass index, hypertension, diabetes or family history. Hematuria was more prevalent among patients with genetic causes. We found 19 pathogenic variants in COL4A3-5 genes in 16 (29.3%) patients. NPHS2 mutations were identified in 6 (16.2%) patients. The remaining cases had variants affecting INF2, OCRL, ACTN4 genes or APOL1 high-risk alleles. FSGS-related genetic variants were more common in SRNS-FSGS than in FSGS-UC (41.7% vs 32.7%). Four SRNS-FSGS patients presented with NPHS2 disease-causing variants. COL4A variants were the most prevalent finding in FSGS-UC patients, with 12 patients carrying disease-causing variants in these genes. Conclusions FSGS-related variants were detected in a substantial number of patients with SRNS-FSGS or FSGS-UC, regardless of age of onset of disease or the patient's family history. In our experience, genetic testing should be performed in routine clinical practice for the diagnosis of this group of patients.
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Affiliation(s)
- Ana María Tato
- Department of Nephrology, Hospital Universitario Fundación Alcorcón, Alcorcón, Spain
| | - Noa Carrera
- Laboratorio de Nefroloxía (No. 11), Grupo de Xenética e Bioloxía do Desenvolvemento das Enfermidades Renais, Instituto de investigación sanitaria de Santiago de Compostela – IDIS, Santiago de Compostela, Spain
| | - Maria García-Murias
- Laboratorio de Nefroloxía (No. 11), Grupo de Xenética e Bioloxía do Desenvolvemento das Enfermidades Renais, Instituto de investigación sanitaria de Santiago de Compostela – IDIS, Santiago de Compostela, Spain
| | - Amir Shabaka
- Department of Nephrology, Hospital Universitario Fundación Alcorcón, Alcorcón, Spain
| | - Ana Ávila
- Department of Nephrology, Hospital Universitario Doctor Peset, Valencia, Spain
| | | | - Cristina Rabasco
- Department of Nephrology, Hospital Universitario Reina Sofía, Córdoba, Spain
| | - Karina Soto
- Department of Nephrology, Hospital Fernando Fonseca, Lisbon, Portugal
| | | | | | | | - Ana Huerta
- Department of Nephrology, Hospital Universitario Puerta de Hierro, Majadahonda, Spain
| | - Carmen Mon
- Department of Nephrology, Hospital Universitario Severo Ochoa, Leganés, Spain
| | | | - Fayna González Cabrera
- Department of Nephrology, Hospital Universitario de Gran Canaria Doctor Negrín, Gran Canaria, Spain
| | | | - Ana Romera
- Department of Nephrology, Hospital de Ciudad Real, Ciudad Real, Spain
| | - Eduardo Gutiérrez
- Department of Nephrology, Hospital Universitario Doce de Octubre, Madrid, Spain
| | - Javier Villacorta
- Department of Nephrology, Hospital Universitario Ramón y Cajal, Madrid, Spain
| | | | - Beatriz Avilés
- Department of Nephrology, Hospital Costa del Sol, Marbella, Spain
| | - Miguel Angel Garca-González
- Laboratorio de Nefroloxía (No. 11), Grupo de Xenética e Bioloxía do Desenvolvemento das Enfermidades Renais, Instituto de investigación sanitaria de Santiago de Compostela – IDIS, Santiago de Compostela, Spain
- Fundación Pública Galega de Medicina Xenómica-SERGAS, Complexo Hospitalario de Santiago de Compostela, Santiago de Compostela, Spain
| | - Gema Fernández-Juárez
- Department of Nephrology, Hospital Universitario La Paz, Madrid, Spain
- Instituto de Investigación de la Paz (IdIPAZ), Madrid, Spain
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Gauckler P, Zitt E, Regele H, Eller K, Säemann MD, Lhotta K, Neumann I, Rudnicki M, Odler B, Kronbichler A, Zschocke J, Windpessl M. [Diagnosis and treatment of focal-segmental glomerulosclerosis-2023]. Wien Klin Wochenschr 2023; 135:638-647. [PMID: 37728649 PMCID: PMC10511576 DOI: 10.1007/s00508-023-02260-x] [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] [Accepted: 07/24/2023] [Indexed: 09/21/2023]
Abstract
The histopathological term focal-segmental glomerulosclerosis comprises different pathogenic processes with the unifying features of a high proteinuria and the name-giving glomerular lesion pattern seen on light microscopy. A differentiation according to the underlying cause into primary, secondary and genetic forms is therefore of utmost importance. The pathogenesis of primary focal-segmental glomerulosclerosis remains unknown but, like minimal-change disease, an autoimmune-mediated process leading to podocyte damage is assumed. Consequently, the unifying term "podocytopathy" is increasingly being used for both entities. Supportive treatment measures to preserve kidney function are important in all subtypes. In contrast, immunosuppressive treatment is only indicated in primary focal-segmental glomerulosclerosis. Steroid-dependence, steroid-resistance and frequently relapsing disease often complicate disease management and necessitate alternative treatment strategies. Here, the Austrian Society of Nephrology (ÖGN) provides consensus recommendations on how to best diagnose and manage patients with focal-segmental glomerulosclerosis.
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Affiliation(s)
- Philipp Gauckler
- Department Innere Medizin IV (Nephrologie und Hypertensiologie), Medizinische Universität Innsbruck, Innsbruck, Österreich
| | - Emanuel Zitt
- Abteilung für Innere Medizin III (Nephrologie, Dialyse und Hypertensiologie), Akademisches Lehrkrankenhaus Feldkirch, Feldkirch, Österreich
| | - Heinz Regele
- Klinisches Institut für Pathologie, Medizinische Universität Wien, Wien, Österreich
| | - Kathrin Eller
- Klinische Abteilung für Nephrologie, Abteilung für Innere Medizin III (Nephrologie, Dialyse und Hypertensiologie), Medizinische Universität Graz, Graz, Österreich
| | - Marcus D. Säemann
- 6.Medizinische Abteilung mit Nephrologie & Dialyse, Klinik Ottakring, Wien, Österreich
- Medizinische Fakultät, SFU, Wien, Österreich
| | - Karl Lhotta
- Abteilung für Innere Medizin III (Nephrologie, Dialyse und Hypertensiologie), Akademisches Lehrkrankenhaus Feldkirch, Feldkirch, Österreich
| | - Irmgard Neumann
- Vasculitis.at, Wien, Österreich
- Immunologiezentrum Zürich (IZZ), Zürich, Schweiz
| | - Michael Rudnicki
- Department Innere Medizin IV (Nephrologie und Hypertensiologie), Medizinische Universität Innsbruck, Innsbruck, Österreich
| | - Balazs Odler
- Klinische Abteilung für Nephrologie, Abteilung für Innere Medizin III (Nephrologie, Dialyse und Hypertensiologie), Medizinische Universität Graz, Graz, Österreich
| | - Andreas Kronbichler
- Department Innere Medizin 4 (Nephrologie und Hypertensiologie), Medizinische Universität Innsbruck, Innsbruck, Österreich
| | - Johannes Zschocke
- Institut für Humangenetik, Medizinische Universität Innsbruck, Innsbruck, Österreich
| | - Martin Windpessl
- Abteilung für Innere Medizin IV, Klinikum Wels-Grieskirchen, Wels, Österreich
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Precise clinicopathologic findings for application of genetic testing in pediatric kidney transplant recipients with focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome. Pediatr Nephrol 2023; 38:417-429. [PMID: 35655039 DOI: 10.1007/s00467-022-05604-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023]
Abstract
BACKGROUND Establishing a molecular genetic diagnosis of focal segmental glomerulosclerosis (FSGS)/steroid-resistant nephrotic syndrome (SRNS) can be useful for predicting post-transplant recurrence. Monogenic causes are reportedly present in approximately 20-30% of patients with FSGS/SRNS. However, the characteristics of patients who are likely to have a monogenic cause remain to be determined. METHODS Pediatric recipients with SRNS and/or biopsy-proven FSGS who underwent their first kidney transplantation at our center between 1999 and 2019 were analyzed. Patients with secondary FSGS/SRNS were excluded. The recipients were divided into three groups: familial/syndromic, presumed primary, and undetermined FSGS/SRNS. Patients who met all of the following criteria were categorized as having presumed primary FSGS/SRNS: (i) nephrotic syndrome, (ii) complete or partial remission with initial steroid therapy and/or additional immunosuppressive therapies, and (iii) diffuse foot process effacement on electron microscopy in the native kidney biopsy. All patients underwent genetic testing using next-generation sequencing. RESULTS Twenty-four patients from 23 families were analyzed in this study. Pathogenic or likely pathogenic variants in FSGS/SRNS-related genes were identified in four of four families, zero of eight families, and 10 of 11 families with familial/syndromic, presumed primary, and undetermined FSGS/SRNS, respectively. Post-transplant recurrence only occurred in patients with presumed primary FSGS/SRNS. CONCLUSIONS Our systematic approach based on precise clinicopathological findings including nephrotic syndrome, treatment responses, and diffuse foot process effacement might be useful to differentiate pediatric kidney transplant recipients with FSGS/SRNS who are likely to have a monogenic cause from patients who are not, and to predict post-transplant recurrence. A higher resolution version of the Graphical abstract is available as Supplementary information.
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8
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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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9
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Watanabe Y, Fujinaga S, Sakuraya K, Ikeda H, Nozu K. Clinical, pathological, and genetic characteristics of cases with asymptomatic proteinuria not manifesting nephrotic syndrome at onset: a single-center retrospective study. Clin Exp Nephrol 2022; 26:453-459. [PMID: 35113255 DOI: 10.1007/s10157-021-02174-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 12/13/2021] [Indexed: 11/26/2022]
Abstract
BACKGROUND Cases with asymptomatic proteinuria (ASP) not manifesting nephrotic syndrome often pathologically show focal segmental glomerulosclerosis (FSGS). However, characteristics of those cases had not been intensively studied so far. METHODS We retrospectively reviewed clinical, pathological, and genetic characteristics of 37 children (median age, 9.3 years) who underwent renal biopsy for persistent isolated proteinuria (urine protein-to-creatinine ratio: UP/C, > 0.2 g/g) between 2003 and 2019. Targeted next-generation sequencing (NGS) was utilized for all patients with FSGS, excluding those with secondary FSGS. RESULTS At biopsy, all patients with FSGS (N = 14) had UP/C ≥ 0.5 g/g and the median UP/C was significantly higher in those with FSGS than those with minor glomerular abnormalities (MGA) (N = 23) (1.49 vs. 0.53 g/g, P < 0.001). Causative variants were found in seven patients with FSGS (TRPC6, WT1, ACTN4, and INF2 in 3, 2, 1, and 1 patient, respectively): all gene variants were in genes manifesting autosomal dominant inheritance mode. The proportion of the perihilar variant was significantly higher in the genetic FSGS patients than in the non-genetic FSGS patients (4/7 vs. 0/7, P < 0.05). Kaplan-Meier analysis showed that the renal survival rate after ASP diagnosis was significantly lower in the genetic FSGS patients than in the non-genetic FSGS and the MGA patients (P < 0.001). CONCLUSIONS UP/C was a simple and useful predictive parameter for the diagnosis of FSGS. APS without nephrotic syndrome at onset may be associated with autosomal dominant causes of FSGS, especially in those with the perihilar variant.
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Affiliation(s)
- Yoshitaka Watanabe
- Division of Nephrology, Saitama Children's Medical Center, 1-2 Shintoshin, Chuo-ku, Saitama-city Saitama, 330-8777, Japan
- Children's Medical Center, Showa University Northern Yokohama Hospital, Yokohama, Kanagawa, Japan
| | - Shuichiro Fujinaga
- Division of Nephrology, Saitama Children's Medical Center, 1-2 Shintoshin, Chuo-ku, Saitama-city Saitama, 330-8777, Japan.
| | - Koji Sakuraya
- Division of Nephrology, Saitama Children's Medical Center, 1-2 Shintoshin, Chuo-ku, Saitama-city Saitama, 330-8777, Japan
| | - Hirokazu Ikeda
- Children's Medical Center, Showa University Northern Yokohama Hospital, Yokohama, Kanagawa, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Kobe, Hyogo, Japan
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10
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Rovin BH, Adler SG, Barratt J, Bridoux F, Burdge KA, Chan TM, Cook HT, Fervenza FC, Gibson KL, Glassock RJ, Jayne DR, Jha V, Liew A, Liu ZH, Mejía-Vilet JM, Nester CM, Radhakrishnan J, Rave EM, Reich HN, Ronco P, Sanders JSF, Sethi S, Suzuki Y, Tang SC, Tesar V, Vivarelli M, Wetzels JF, Floege J. KDIGO 2021 Clinical Practice Guideline for the Management of Glomerular Diseases. Kidney Int 2021; 100:S1-S276. [PMID: 34556256 DOI: 10.1016/j.kint.2021.05.021] [Citation(s) in RCA: 673] [Impact Index Per Article: 224.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 12/13/2022]
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