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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Kalmár T, Turkevi-Nagy S, Bitó L, Kaiser L, Maróti Z, Jakab D, Letoha A, Légrády P, Iványi B. Phenotype-Genotype Correlations in Three Different Cases of Adult-Onset Genetic Focal Segmental Glomerulosclerosis. Int J Mol Sci 2023; 24:17489. [PMID: 38139322 PMCID: PMC10743622 DOI: 10.3390/ijms242417489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Revised: 12/08/2023] [Accepted: 12/12/2023] [Indexed: 12/24/2023] Open
Abstract
This study highlights the importance of a combined diagnostic approach in the diagnosis of rare diseases, such as adult-onset genetic FSGS. We present three adult patient cases evaluated with kidney biopsy for proteinuria, chronic kidney disease, and hypertension, which were suggestive of adult-onset genetic FSGS. Renal biopsy samples and formalin-fixed, paraffin-embedded fetal kidneys were evaluated using standard light microscopical stainings, direct immunofluorescence on cryostat sections, and electron microscopy. Clinical exome sequencing was performed for each case, and 45 FSGS-related genes were analyzed. Identifying mutations in the PAX2, ACTN4, and COL4A5 genes have prompted a re-evaluation of the previous histopathological examinations. The PAX2 mutation led to a thinner nephrogenic zone and decreased number of glomeruli, resulting in oligohydramnios during fetal development and oligomeganephronia and adaptive focal-segmental glomerulosclerosis in adulthood. The ACTN4 mutation caused distinct electron-dense aggregates in podocyte cell bodies, while the COL4A5 mutation led to segmental sclerosis of glomeruli with marked interstitial fibrosis and tubular atrophy. The identification of specific mutations and their histopathological consequences can lead to a better understanding of the disease and its progression, as well as potential treatment options.
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Affiliation(s)
- Tibor Kalmár
- Department of Pediatrics, Albert Szent-Györgyi Health Centre, University of Szeged, Temesvari krt 35-37, 6726 Szeged, Hungary (Z.M.)
| | - Sándor Turkevi-Nagy
- Department of Pediatrics, Albert Szent-Györgyi Health Centre, University of Szeged, Temesvari krt 35-37, 6726 Szeged, Hungary (Z.M.)
| | - László Bitó
- Department of Internal Medicine, Albert Szent-Györgyi Health Centre, University of Szeged, 6726 Szeged, Hungary
| | - László Kaiser
- Department of Pediatrics, Albert Szent-Györgyi Health Centre, University of Szeged, Temesvari krt 35-37, 6726 Szeged, Hungary (Z.M.)
| | - Zoltán Maróti
- Department of Pediatrics, Albert Szent-Györgyi Health Centre, University of Szeged, Temesvari krt 35-37, 6726 Szeged, Hungary (Z.M.)
| | - Dániel Jakab
- Department of Pediatrics, Albert Szent-Györgyi Health Centre, University of Szeged, Temesvari krt 35-37, 6726 Szeged, Hungary (Z.M.)
| | - Annamária Letoha
- Department of Internal Medicine, Centre of Clinical Infectology and Acute Internal Medicine, Albert Szent-Györgyi Health Centre, University of Szeged, 6726 Szeged, Hungary
| | - Péter Légrády
- Department of Internal Medicine, Albert Szent-Györgyi Health Centre, University of Szeged, 6726 Szeged, Hungary
| | - Béla Iványi
- Department of Pediatrics, Albert Szent-Györgyi Health Centre, University of Szeged, Temesvari krt 35-37, 6726 Szeged, Hungary (Z.M.)
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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: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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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