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Mitrotti A, Giliberti M, Di Leo V, di Bari I, Pontrelli P, Gesualdo L. Hidden genetics behind glomerular scars: an opportunity to understand the heterogeneity of focal segmental glomerulosclerosis? Pediatr Nephrol 2024; 39:1685-1707. [PMID: 37728640 PMCID: PMC11026212 DOI: 10.1007/s00467-023-06046-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Revised: 05/02/2023] [Accepted: 05/30/2023] [Indexed: 09/21/2023]
Abstract
Focal segmental glomerulosclerosis (FSGS) is a complex disease which describes different kinds of kidney defects, not exclusively linked with podocyte defects. Since nephrin mutation was first described in association with early-onset nephrotic syndrome (NS), many advancements have been made in understanding genetic patterns associated with FSGS. New genetic causes of FSGS have been discovered, displaying unexpected genotypes, and recognizing possible site of damage. Many recent large-scale sequencing analyses on patients affected by idiopathic chronic kidney disease (CKD), kidney failure (KF) of unknown origin, or classified as FSGS, have revealed collagen alpha IV genes, as one of the most frequent sites of pathogenic mutations. Also, recent interest in complex and systemic lysosomal storage diseases, such as Fabry disease, has highlighted GLA mutations as possible causes of FSGS. Tubulointerstitial disease, recently classified by KDIGO based on genetic subtypes, when associated with UMOD variants, may phenotypically gain FSGS features, as well as ciliopathy genes or others, otherwise leading to completely different phenotypes, but found carrying pathogenic variants with associated FSGS phenotype. Thus, glomerulosclerosis may conceal different heterogeneous conditions. When a kidney biopsy is performed, the principal objective is to provide an accurate diagnosis. The broad spectrum of phenotypic expression and genetic complexity is demonstrating that a combined path of management needs to be applied. Genetic investigation should not be reserved only to selected cases, but rather part of medical management, integrating with clinical and renal pathology records. FSGS heterogeneity should be interpreted as an interesting opportunity to discover new pathways of CKD, requiring prompt genotype-phenotype correlation. In this review, we aim to highlight how FSGS represents a peculiar kidney condition, demanding multidisciplinary management, and in which genetic analysis may solve some otherwise unrevealed idiopathic cases. Unfortunately there is not a uniform correlation between specific mutations and FSGS morphological classes, as the same variants may be identified in familial cases or sporadic FSGS/NS or manifest a variable spectrum of the same disease. These non-specific features make diagnosis challenging. The complexity of FSGS genotypes requires new directions. Old morphological classification does not provide much information about the responsible cause of disease and misdiagnoses may expose patients to immunosuppressive therapy side effects, mistaken genetic counseling, and misguided kidney transplant programs.
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Affiliation(s)
- Adele Mitrotti
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy.
| | - Marica Giliberti
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Vincenzo Di Leo
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Ighli di Bari
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Paola Pontrelli
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
| | - Loreto Gesualdo
- Precision and Regenerative Medicine and Ionian Area, Nephrology, Dialysis and Transplantation Unit, Department of Emergency and Organ Transplantation, University of Bari Aldo Moro, Bari, Italy
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Riedhammer KM, Simmendinger H, Tasic V, Putnik J, Abazi-Emini N, Stajic N, Berutti R, Weidenbusch M, Patzer L, Lungu A, Milosevski-Lomic G, Günthner R, Braunisch MC, Ćomić J, Hoefele J. Is there a dominant-negative effect in individuals with heterozygous disease-causing variants in COL4A3/COL4A4? Clin Genet 2024; 105:406-414. [PMID: 38214412 DOI: 10.1111/cge.14471] [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: 10/29/2023] [Revised: 12/01/2023] [Accepted: 12/04/2023] [Indexed: 01/13/2024]
Abstract
Alport syndrome (AS) shows a broad phenotypic spectrum ranging from isolated microscopic hematuria (MH) to end-stage kidney disease (ESKD). Monoallelic disease-causing variants in COL4A3/COL4A4 have been associated with autosomal dominant AS (ADAS) and biallelic variants with autosomal recessive AS (ARAS). The aim of this study was to analyze clinical and genetic data regarding a possible genotype-phenotype correlation in individuals with disease-causing variants in COL4A3/COL4A4. Eighty-nine individuals carrying at least one COL4A3/COL4A4 variant classified as (likely) pathogenic according to the American College of Medical Genetics guidelines and current amendments were recruited. Clinical data concerning the prevalence and age of first reported manifestation of MH, proteinuria, ESKD, and extrarenal manifestations were collected. Individuals with monoallelic non-truncating variants reported a significantly higher prevalence and earlier diagnosis of MH and proteinuria than individuals with monoallelic truncating variants. Individuals with biallelic variants were more severely affected than those with monoallelic variants. Those with biallelic truncating variants were more severely affected than those with compound heterozygous non-truncating/truncating variants or individuals with biallelic non-truncating variants. In this study an association of heterozygous non-truncating COL4A3/COL4A4 variants with a more severe phenotype in comparison to truncating variants could be shown indicating a potential dominant-negative effect as an explanation for this observation. The results for individuals with ARAS support the, still scarce, data in the literature.
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Affiliation(s)
- Korbinian M Riedhammer
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
| | - Hannes Simmendinger
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
| | - Velibor Tasic
- Medical Faculty of Skopje, University Children's Hospital, Macedonia
| | - Jovana Putnik
- Institute for Mother and Child Health Care of Serbia "Dr Vukan Čupić", Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Nora Abazi-Emini
- Medical Faculty of Skopje, University Children's Hospital, Macedonia
| | - Natasa Stajic
- Institute for Mother and Child Health Care of Serbia "Dr Vukan Čupić", Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Riccardo Berutti
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
| | - Marc Weidenbusch
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Ludwig-Maximilians University, Munich, Germany
| | - Ludwig Patzer
- Department of Pediatric Nephrology, Children's Hospital St. Elisabeth and St. Barbara, Halle/Saale, Germany
| | - Adrian Lungu
- Pediatric Nephrology Department, Fundeni Clinical Institute, Bucharest, Romania
| | - Gordana Milosevski-Lomic
- Institute for Mother and Child Health Care of Serbia "Dr Vukan Čupić", Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Roman Günthner
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
| | - Matthias C Braunisch
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
| | - Jasmina Ćomić
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, TUM School of Medicine and Health, Munich, Germany
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3
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Ćomić J, Riedhammer KM, Günthner R, Schaaf CW, Richthammer P, Simmendinger H, Kieffer D, Berutti R, Tasic V, Abazi-Emini N, Nushi-Stavileci V, Putnik J, Stajic N, Lungu A, Gross O, Renders L, Heemann U, Braunisch MC, Meitinger T, Hoefele J. The multifaceted phenotypic and genotypic spectrum of type-IV-collagen-related nephropathy—A human genetics department experience. Front Med (Lausanne) 2022; 9:957733. [PMID: 36117978 PMCID: PMC9470833 DOI: 10.3389/fmed.2022.957733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 07/29/2022] [Indexed: 11/28/2022] Open
Abstract
Disease-causing variants in COL4A3-5 are associated with type-IV-collagen-related nephropathy, a genetically and phenotypically multifaceted disorder comprising Alport syndrome (AS) and thin basement membrane nephropathy (TBMN) and autosomal, X-linked and a proposed digenic inheritance. Initial symptoms of individuals with AS are microscopic hematuria followed by proteinuria leading to kidney failure (90% on dialysis < age 40 years). In contrast, individuals with TBMN, an outdated histology-derived term, present with microscopic hematuria, only some of them develop kidney failure (>50 years of age). An early diagnosis of type-IV-collagen-related nephropathy is essential for optimized therapy and slowing of the disease. Sixty index cases, in whom exome sequencing had been performed and with disease-causing variant(s) in COL4A3-5, were evaluated concerning their clinical tentative diagnosis and their genotype. Of 60 reevaluated individuals with type-IV-collagen-related nephropathy, 72% had AS, 23% TBMN and 5% focal segmental glomerulosclerosis (FSGS) as clinical tentative diagnosis. The FSGS cases had to be re-classified as having type-IV-collagen-related nephropathy. Twelve percent of cases had AS as clinical tentative diagnosis and a monoallelic disease-causing variant in COL4A3/4 but could not be classified as autosomal dominant AS because of limited or conflicting clinical data. This study illustrates the complex clinical and genetic picture of individuals with a type IV-collagen-related nephropathy indicating the need of a refined nomenclature and the more interdisciplinary teamwork of clinicians and geneticists as the key to optimized patient care.
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Affiliation(s)
- Jasmina Ćomić
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Korbinian M. Riedhammer
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Roman Günthner
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Christian W. Schaaf
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Patrick Richthammer
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Hannes Simmendinger
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Donald Kieffer
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Riccardo Berutti
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Velibor Tasic
- University Children's Hospital, Medical Faculty of Skopje, Skopje, North Macedonia
| | - Nora Abazi-Emini
- University Children's Hospital, Medical Faculty of Skopje, Skopje, North Macedonia
| | | | - Jovana Putnik
- Institute for Mother and Child Health Care of Serbia “Dr. Vukan Čupić”, Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Nataša Stajic
- Institute for Mother and Child Health Care of Serbia “Dr. Vukan Čupić”, Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Adrian Lungu
- University Children's Hospital, Medical Faculty of Skopje, Skopje, North Macedonia
| | - Oliver Gross
- Clinic of Nephrology and Rheumatology, University Medical Center Göttingen, University of Göttingen, Göttingen, Germany
| | - Lutz Renders
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Uwe Heemann
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Matthias C. Braunisch
- Department of Nephrology, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum rechts der Isar, Technical University of Munich, School of Medicine, Munich, Germany
- *Correspondence: Julia Hoefele
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Gyarmati G, Shroff UN, Izuhara A, Hou X, Da Sacco S, Sedrakyan S, Lemley KV, Amann K, Perin L, Peti-Peterdi J. Intravital imaging reveals glomerular capillary distension and endothelial and immune cell activation early in Alport syndrome. JCI Insight 2021; 7:152676. [PMID: 34793332 PMCID: PMC8765042 DOI: 10.1172/jci.insight.152676] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 11/17/2021] [Indexed: 11/17/2022] Open
Abstract
Alport syndrome (AS) is a genetic disorder caused by mutations in type IV collagen that lead to defective glomerular basement membrane, glomerular filtration barrier (GFB) damage, and progressive chronic kidney disease. While the genetic basis of AS is well known, the molecular and cellular mechanistic details of disease pathogenesis have been elusive, hindering the development of mechanism-based therapies. Here, we performed intravital multiphoton imaging of the local kidney tissue microenvironment in a X-linked AS mouse model to directly visualize the major drivers of AS pathology. Severely distended glomerular capillaries and aneurysms were found accompanied by numerous microthrombi, increased glomerular endothelial surface layer (glycocalyx) and immune cell homing, GFB albumin leakage, glomerulosclerosis, and interstitial fibrosis by 5 months of age, with an intermediate phenotype at 2 months. Renal histology in mouse or patient tissues largely failed to detect capillary aberrations. Treatment of AS mice with hyaluronidase or the ACE inhibitor enalapril reduced the excess glomerular endothelial glycocalyx and blocked immune cell homing and GFB albumin leakage. This study identified central roles of glomerular mechanical forces and endothelial and immune cell activation early in AS, which could be therapeutically targeted to reduce mechanical strain and local tissue inflammation and improve kidney function.
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Affiliation(s)
- Georgina Gyarmati
- Department of Physiology and Neuroscience, University of Southern California, Los Angeles, United States of America
| | - Urvi Nikhil Shroff
- Department of Physiology and Neuroscience, University of Southern California, Los Angeles, United States of America
| | - Audrey Izuhara
- Department of Physiology and Neuroscience, University of Southern California, Los Angeles, United States of America
| | - Xiaogang Hou
- Division of Urology, Children's Hospital Los Angeles, Los Angeles, United States of America
| | - Stefano Da Sacco
- Division of Urology, Children's Hospital Los Angeles, Los Angeles, United States of America
| | - Sargis Sedrakyan
- Division of Urology, Children's Hospital Los Angeles, Los Angeles, United States of America
| | - Kevin V Lemley
- Department of Pediatics, Children's Hospital Los Angeles, Los angeles, United States of America
| | - Kerstin Amann
- Department of Nephropathology, Friedrich Alexander University, Erlangen, Germany
| | - Laura Perin
- Division of Urology, Children's Hospital Los Angeles, Los Angeles, United States of America
| | - János Peti-Peterdi
- Department of Physiology and Neuroscience, University of Southern California, Los Angeles, United States of America
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Sienes Bailo P, Bancalero Flores JL, Lahoz Alonso R, Santamaría González M, Gutiérrez Dalmau A, Álvarez de Andrés S, Izquierdo Álvarez S. A novel variant in the COL4A3 gene: etiology of Alport syndrome type 2 in a 38-year-old male with suspected hereditary kidney disease. ADVANCES IN LABORATORY MEDICINE 2021; 2:451-462. [PMID: 37362409 PMCID: PMC10197298 DOI: 10.1515/almed-2021-0058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/12/2021] [Indexed: 06/28/2023]
Abstract
Objectives Patients with Alport syndrome develop progressive kidney function deterioration, sensorineural hearing loss, and ocular abnormalities. This condition is caused by mutations in COL4A5 (X-linked inheritance), COL4A3 and COL4A4 (autosomal dominant or recessive inheritance), and encoding type IV collagen α3, α4, and α5, respectively. If left untreated, clinical symptoms progress from microscopic hematuria to proteinuria, progressive kidney failure, and end-stage kidney disease. At present, kidney transplantation is the only effective approach. Next-generation sequencing is the method of choice for the diagnosis of this condition. Case presentation We report the case of a young man with chronic kidney disease who eventually underwent transplantation. Molecular testing made it possible to determine the etiology of his clinical symptoms and autosomal recessive Alport syndrome type 2. The patient was found to be a compound heterozygote for two missense variants (trans configuration) in the COL4A3 gene: A likely pathogenic variant c.4981C>T (p.Arg1661Cys) in exon 52 inherited from the mother (described elsewhere), and another variant of uncertain significance, c.943G>A (p.Gly315Ser), in exon 17 inherited from the father that has not been previously reported in the literature or found in relevant databases. Conclusions Following genetic confirmation, genetic counseling was provided to the patient and his direct relatives.
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Affiliation(s)
- Paula Sienes Bailo
- Department of Clinical Biochemistry, Hospital Universitario Miguel Servet, Zaragoza, Spain
| | | | - Raquel Lahoz Alonso
- Department of Clinical Biochemistry, Hospital Universitario Miguel Servet, Zaragoza, Spain
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Genotype-phenotype correlations and nephroprotective effects of RAAS inhibition in patients with autosomal recessive Alport syndrome. Pediatr Nephrol 2021; 36:2719-2730. [PMID: 33772369 PMCID: PMC8370956 DOI: 10.1007/s00467-021-05040-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 02/20/2021] [Accepted: 03/02/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Autosomal recessive Alport syndrome (ARAS) is caused by pathogenic variants in both alleles of either COL4A3 or COL4A4 genes. Reports on ARAS are rare due to small patient numbers and there are no reports on renin-angiotensin-aldosterone system (RAAS) inhibition therapy in ARAS. METHODS Retrospective study in 101 patients with ARAS from Chinese Registry Database of Hereditary Kidney Diseases and European Alport Registry. Genotype-phenotype correlations and nephroprotective effects of RAAS inhibition in ARAS were evaluated. RESULTS Median age was 15 years (range 1.5-46 years). Twelve patients progressed to stage 5 chronic kidney disease (CKD5) at median age 20.5 years. Patients without missense variants had both higher prevalence and earlier onset age of hearing loss, nephrotic-range proteinuria, more rapid decline of eGFR, and earlier onset age of CKD5 compared to patients with 1 or 2 missense variants. Most patients (79/101, 78%) currently are treated with RAAS inhibitors; median age at therapy initiation was 10 years and mean duration 6.5 ± 6.0 years. Median age at CKD5 for untreated patients was 24 years. RAAS inhibition therapy delayed CKD5 onset in those with impaired kidney function (T-III) to median age 35 years, but is undefined in treated patients with proteinuria (T-II) due to low number of events. No treated patients with microalbuminuria (T-I) progressed to CKD5. ARAS patients with 1 or 2 missense variants showed better response to treatment than patients with non-missense-variants. CONCLUSIONS Our study provides the first evidence for early use of RAAS inhibition therapy in patients with ARAS. Furthermore, genotype in ARAS correlates with response to therapy in favor of missense variants.
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Matthaiou A, Poulli T, Deltas C. Prevalence of clinical, pathological and molecular features of glomerular basement membrane nephropathy caused by COL4A3 or COL4A4 mutations: a systematic review. Clin Kidney J 2020; 13:1025-1036. [PMID: 33391746 PMCID: PMC7769542 DOI: 10.1093/ckj/sfz176] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Accepted: 11/06/2019] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Patients heterozygous for COL4A3 or COL4A4 mutations show a wide spectrum of disease, extending from familial isolated microscopic haematuria, as a result of thin basement membranes (TBMs), to autosomal dominant Alport syndrome (ADAS) and end-stage renal disease (ESRD). Many patients are mentioned in the literature under the descriptive diagnosis of TBM nephropathy (TBMN), in which case it actually describes a histological finding that represents the carriers of autosomal recessive Alport syndrome (ARAS), a severe glomerulopathy, as most patients reach ESRD at a mean age of 25 years. METHODS We performed a systematic literature review for patients with heterozygous COL4A3/A4 mutations with the aim of recording the spectrum and frequency of pathological features. We searched three databases (PubMed, Embase and Scopus) using the keywords 'Autosomal Dominant Alport Syndrome' OR 'Thin Basement Membrane Disease' OR 'Thin Basement Membrane Nephropathy'. We identified 48 publications reporting on 777 patients from 258 families. RESULTS In total, 29% of the patients developed chronic kidney disease (CKD) and 15.1% reached ESRD at a mean age of 52.8 years. Extrarenal features and typical Alport syndrome (AS) findings had a low prevalence in patients as follows: hearing loss, 16%; ocular lesions, 3%; basement membrane thickening, 18.4%; and podocyte foot process effacement, 6.9%. Data for 76 patients from 54 families emphasize extensive inter- and intrafamilial heterogeneity, with age at onset of ESRD ranging between 21 and 84 years (mean 52.8). CONCLUSIONS The analysis enabled a comparison of the clinical course of patients with typical ARAS or X-linked AS with those with heterozygous COL4A mutations diagnosed with TBMN or ADAS. Despite the consequence of a potential ascertainment bias, an important outcome is that TBM poses a global high risk of developing severe CKD, over a long follow-up, with a variable spectrum of other findings. The results are useful to practicing nephrologists for better evaluation of patients.
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Affiliation(s)
| | | | - Constantinos Deltas
- Molecular Medicine Research Center and Laboratory of Molecular and Medical Genetics, Department of Biological Sciences, University of Cyprus, Nicosia, Cyprus
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8
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Braunisch MC, Riedhammer KM, Herr PM, Draut S, Günthner R, Wagner M, Weidenbusch M, Lungu A, Alhaddad B, Renders L, Strom TM, Heemann U, Meitinger T, Schmaderer C, Hoefele J. Identification of disease-causing variants by comprehensive genetic testing with exome sequencing in adults with suspicion of hereditary FSGS. Eur J Hum Genet 2020; 29:262-270. [PMID: 32887937 PMCID: PMC7868362 DOI: 10.1038/s41431-020-00719-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 07/15/2020] [Accepted: 08/11/2020] [Indexed: 11/21/2022] Open
Abstract
In about 30% of infantile, juvenile, or adolescent patients with steroid-resistant nephrotic syndrome (SRNS), a monogenic cause can be identified. The histological finding in SRNS is often focal segmental glomerulosclerosis (FSGS). Genetic data on adult patients are scarce with low diagnostic yields. Exome sequencing (ES) was performed in patients with adult disease onset and a high likelihood for hereditary FSGS. A high likelihood was defined if at least one of the following criteria was present: absence of a secondary cause, ≤25 years of age at initial manifestation, kidney biopsy with suspicion of a hereditary cause, extrarenal manifestations, and/or positive familial history/reported consanguinity. Patients were excluded if age at disease onset was <18 years. In 7/24 index patients with adult disease onset, a disease-causing variant could be identified by ES leading to a diagnostic yield of 29%. Eight different variants were identified in six known genes associated with monogenic kidney diseases. Six of these variants had been described before as disease-causing. In patients with a disease-causing variant, the median age at disease onset and end-stage renal disease was 26 and 38 years, respectively. The overall median time to a definite genetic diagnosis was 9 years. In 29% of patients with adult disease onset and suspected hereditary FSGS, a monogenic cause could be identified. The long delay up to the definite genetic diagnosis highlights the importance of obtaining an early genetic diagnosis to allow for personalized treatment options including weaning of immunosuppressive treatment, avoidance of repeated renal biopsy, and provision of accurate genetic counseling.
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Affiliation(s)
- Matthias Christoph Braunisch
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.,Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Korbinian Maria Riedhammer
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.,Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Pierre-Maurice Herr
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Sarah Draut
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Roman Günthner
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.,Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Matias Wagner
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany.,Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Marc Weidenbusch
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Ludwig-Maximilians University, Munich, Germany
| | - Adrian Lungu
- Pediatric Nephrology Department, Fundeni Clinical Institute, Bucharest, Romania
| | - Bader Alhaddad
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Lutz Renders
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Tim M Strom
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Uwe Heemann
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Thomas Meitinger
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.,Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Christoph Schmaderer
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.
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Riedhammer KM, Braunisch MC, Günthner R, Wagner M, Hemmer C, Strom TM, Schmaderer C, Renders L, Tasic V, Gucev Z, Nushi-Stavileci V, Putnik J, Stajić N, Weidenbusch M, Uetz B, Montoya C, Strotmann P, Ponsel S, Lange-Sperandio B, Hoefele J. Exome Sequencing and Identification of Phenocopies in Patients With Clinically Presumed Hereditary Nephropathies. Am J Kidney Dis 2020; 76:460-470. [PMID: 32359821 DOI: 10.1053/j.ajkd.2019.12.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2019] [Accepted: 12/15/2019] [Indexed: 12/11/2022]
Abstract
RATIONALE & OBJECTIVE Hereditary nephropathies are clinically and genetically heterogeneous disorders. For some patients, the clinical phenotype corresponds to a specific hereditary disease but genetic testing reveals that the expected genotype is not present (phenocopy). The aim of this study was to evaluate the spectrum and frequency of phenocopies identified by using exome sequencing in a cohort of patients who were clinically suspected to have hereditary kidney disorders. STUDY DESIGN Cross-sectional cohort study. SETTING & PARTICIPANTS 174 unrelated patients were recruited for exome sequencing and categorized into 7 disease groups according to their clinical presentation. They included autosomal dominant tubulointerstitial kidney disease, Alport syndrome, congenital anomalies of the kidney and urinary tract, ciliopathy, focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome, VACTERL association, and "other." RESULTS A genetic diagnosis (either likely pathogenic or pathogenic variant according to the guidelines of the American College of Medical Genetics) was established using exome sequencing in 52 of 174 (30%) cases. A phenocopy was identified for 10 of the 52 exome sequencing-solved cases (19%), representing 6% of the total cohort. The most frequent phenocopies (n=5) were associated with genetic Alport syndrome presenting clinically as focal segmental glomerulosclerosis/steroid-resistant nephrotic syndrome. Strictly targeted gene panels (<25 kilobases) did not identify any of the phenocopy cases. LIMITATIONS The spectrum of described phenocopies is small. Selection bias may have altered the diagnostic yield within disease groups in our study population. The study cohort was predominantly of non-Finnish European descent, limiting generalizability. Certain hereditary kidney diseases cannot be diagnosed by using exome sequencing (eg, MUC1-autosomal dominant tubulointerstitial kidney disease). CONCLUSIONS Phenocopies led to the recategorization of disease and altered clinical management. This study highlights that exome sequencing can detect otherwise occult genetic heterogeneity of kidney diseases.
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Affiliation(s)
- Korbinian M Riedhammer
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany; Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Matthias C Braunisch
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany; Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Roman Günthner
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany; Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Matias Wagner
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany; Institute of Neurogenomics, Helmholtz Zentrum München, Neuherberg, Germany; Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Clara Hemmer
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Tim M Strom
- Institute of Human Genetics, Helmholtz Zentrum München, Neuherberg, Germany
| | - Christoph Schmaderer
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Lutz Renders
- Department of Nephrology, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany
| | - Velibor Tasic
- University Children's Hospital, Medical Faculty of Skopje, Macedonia
| | - Zoran Gucev
- University Children's Hospital, Medical Faculty of Skopje, Macedonia
| | | | - Jovana Putnik
- Institute for Mother and Child Health Care of Serbia "Dr Vukan Čupić", Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Nataša Stajić
- Institute for Mother and Child Health Care of Serbia "Dr Vukan Čupić", Department of Nephrology, University of Belgrade, Faculty of Medicine, Belgrade, Serbia
| | - Marc Weidenbusch
- Nephrologisches Zentrum, Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Ludwig-Maximilians University, Munich, Germany
| | - Barbara Uetz
- München-Klinik Schwabing, Klinikum rechts der Isar, Technical University of Munich, Children's Hospital, Pediatric Nephrology, Munich, Germany; KfH-Kindernierenzentrum, Munich, Germany
| | | | - Peter Strotmann
- München-Klinik Schwabing, Klinikum rechts der Isar, Technical University of Munich, Children's Hospital, Pediatric Nephrology, Munich, Germany
| | - Sabine Ponsel
- Division of Pediatric Nephrology, Dr. v. Hauner Children's Hospital, Ludwig-Maximilians University, Munich, Germany
| | - Baerbel Lange-Sperandio
- Division of Pediatric Nephrology, Dr. v. Hauner Children's Hospital, Ludwig-Maximilians University, Munich, Germany
| | - Julia Hoefele
- Institute of Human Genetics, Klinikum rechts der Isar, School of Medicine, Technical University of Munich, Munich, Germany.
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Davis J, Tjipto A, Hegerty K, Mallett A. The use of electron microscopy in the diagnosis of focal segmental glomerulosclerosis: are current pathological techniques missing important abnormalities in the glomerular basement membrane? F1000Res 2019; 8:1204. [PMID: 31781368 PMCID: PMC6854873 DOI: 10.12688/f1000research.19997.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/04/2019] [Indexed: 01/15/2023] Open
Abstract
Background: There is an increasing appreciation that variants of the
COL4A genes may be associated with the development of focal segmental glomerulosclerosis (FSGS). On electron microscopy, such variants may produce characteristic changes within the glomerular basement membrane (GBM). These changes may be missed if glomerular lesions histologically diagnosed as FSGS on light microscopy are not subjected to electron microscopy. Methods: We conducted a retrospective cohort analysis of all patients presenting to two hospitals who received a primary histological diagnosis of FSGS to see if these samples underwent subsequent electron microscopy. Each such sample was also scrutinised for the presence of characteristic changes of an underlying type IV collagen disorder Results: A total of 43 patients were identified. Of these, only 30 underwent electron microscopy. In two samples there were histological changes detected that might have suggested the underlying presence of a type IV collagen disorder. Around one in three biopsy samples that had a histological diagnosis of FSGS were not subjected to electron microscopy. Conclusion: Renal biopsy samples that have a histological diagnosis of primary FSGS not subjected to subsequent electron microscopy may potentially miss ultrastructural changes in the GBM that could signify an underlying type IV collagen disorder as the patient’s underlying disease process. This could potentially affect both them and their families’ investigative and management decisions given potential for implications for transplant, heritability and different disease pathogenesis. This represents a gap in care which should be reflected upon and rectified via iterative standard care and unit-level quality assurance initiatives.
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Affiliation(s)
- Justin Davis
- Department of Nephrology, Barwon Health, Geelong, Victoria, 3220, Australia
| | - Alwie Tjipto
- Department of Nephrology, Barwon Health, Geelong, Victoria, 3220, Australia
| | - Katharine Hegerty
- Department of Nephrology, Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
| | - Andrew Mallett
- Department of Nephrology, Royal Brisbane and Women's Hospital, Herston, Queensland, Australia
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11
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Shang S, Peng F, Wang T, Wu X, Li P, Li Q, Chen XM. Genotype-phenotype correlation and prognostic impact in Chinese patients with Alport Syndrome. Mol Genet Genomic Med 2019; 7:e00741. [PMID: 31144478 PMCID: PMC6625365 DOI: 10.1002/mgg3.741] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Revised: 04/12/2019] [Accepted: 04/15/2019] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Alport Syndrome (AS) is a progressive hereditary glomerular disease. It is often accompanied by sensorineural hearing loss and ocular abnormalities and can sometimes develop into end stage renal disease (ESRD), which is caused by mutations in the genes encoding the collagen type IV family of proteins. METHODS This study analyzed the association between the clinical data of seven AS families and genes and the disease progression of different mutation types, including COL4A3 (OMIM 120070),COL4A4 (OMIM 120131), and COL4A5 (OMIM303630). RESULTS A total of six new pathogenic mutation sites, one complex heterozygous mutation at COL4A3, and a combined mutation of COL4A5 and INF2 (OMIM 610982) were identified in this study. It was revealed that the clinical manifestations of X-linked AS caused by mutations in the COL4A5 gene were more severe in males than in females. In addition, the difference in patient phenotype can be attributed to the location of gene mutations affecting the protein domain or functional domain. Our data suggested that the gene deletion and nonsense mutations had a high risk for progression to ESRD. CONCLUSION Our results revealed the spectrum of type IV collagen genes, which contribute to the enrichment of database resources and has important implications in the diagnosis, prognosis, and guiding treatment of AS.
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Affiliation(s)
- Shunlai Shang
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China
| | - Fei Peng
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China.,School of Medicine, Nankai University, Tianjin, China
| | - Tao Wang
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China
| | - Xiaoyuan Wu
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China
| | - Ping Li
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China
| | - Qinggang Li
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China
| | - Xiang M Chen
- Department of Nephrology, State Key Laboratory of Kidney Diseases, National Clinical Research Center for Kidney Diseases, Chinese PLA General Hospital, Medical School of Chinese PLA, Chinese PLA Institute of Nephrology, Beijing, China
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12
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Features of Autosomal Recessive Alport Syndrome: A Systematic Review. J Clin Med 2019; 8:jcm8020178. [PMID: 30717457 PMCID: PMC6406612 DOI: 10.3390/jcm8020178] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2018] [Revised: 01/27/2019] [Accepted: 01/31/2019] [Indexed: 01/16/2023] Open
Abstract
Alport syndrome (AS) is one of the most frequent hereditary nephritis leading to end-stage renal disease (ESRD). Although X-linked (XLAS) inheritance is the most common form, cases with autosomal recessive inheritance with mutations in COL4A3 or COL4A4 are being increasingly recognized. A systematic review was conducted on autosomal recessive Alport syndrome (ARAS). Electronic databases were searched using related terms (until Oct 10th, 2018). From 1601 articles searched, there were 26 eligible studies with 148 patients. Female and male patients were equally affected. About 62% of patients had ESRD, 64% had sensorineural hearing loss (SNHL) and 17% had ocular manifestation. The median at onset was 2.5 years for hematuria (HU), 21 years for ESRD, and 13 years for SNHL. Patients without missense mutations had more severe outcomes at earlier ages, while those who had one or two missense mutations had delayed onset and lower prevalence of extrarenal manifestations. Of 49 patients with kidney biopsy available for electron microscopy (EM) pathology, 42 (86%) had typical glomerular basement membrane (GBM) changes, while 5 (10%) patients showed GBM thinning only. SNHL developed earlier than previously reported. There was a genotype phenotype correlation according to the number of missense mutations. Patients with missense mutations had delayed onset of hematuria, ESRD, and SNHL and lower prevalence of extrarenal manifestations.
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Yao T, Udwan K, John R, Rana A, Haghighi A, Xu L, Hack S, Reich HN, Hladunewich MA, Cattran DC, Paterson AD, Pei Y, Barua M. Integration of Genetic Testing and Pathology for the Diagnosis of Adults with FSGS. Clin J Am Soc Nephrol 2019; 14:213-223. [PMID: 30647093 PMCID: PMC6390925 DOI: 10.2215/cjn.08750718] [Citation(s) in RCA: 89] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 11/27/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND AND OBJECTIVES FSGS and nephrotic syndrome studies have shown that single gene causes are more likely to be found in pediatric cases than adults. Consequently, many studies have examined limited gene panels in largely pediatric cohorts. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Whole-exome sequencing was performed in adults with FSGS diagnosed between 1976 and 2017 in the Toronto GN Registry. An expanded panel of 109 genes linked to FSGS, glomerular basement membrane abnormalities, as well as causes of pediatric ESKD including congenital abnormalities of the kidney and urinary tract (CAKUT) and nephronophthisis, were examined. RESULTS The cohort was composed of 193 individuals from 179 families. Nearly half (49%) developed ESKD at a mean age of 47±17 years. The genetic diagnostic rate was 11%. Of definitely pathogenic variants, 55% were in COL4A (A3/A4/A5), 40% were in podocyte genes, and 5% were in CAKUT genes. Many, but not all individuals with COL4A definitely pathogenic variants had some evidence of glomerular basement membrane abnormalities. The estimated mean survival/age of kidney failure for individuals with COL4A definitely pathogenic variants was 58 years (95% confidence interval, 49 to 69), far later than what has been reported in the literature. Likely pathogenic variants were identified in an additional 9% of the cohort, with most in COL4A. Correlation with glomerular basement membrane morphology suggested a causal role for at least some of these likely pathogenic variants. CONCLUSIONS Even with an expanded gene panel, we find that COL4A disorders are the leading monogenic cause in adults diagnosed with FSGS. PODCAST This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2019_01_15_CJASNPodcast_19_02_.mp3.
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Affiliation(s)
- Tony Yao
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada
| | - Khalil Udwan
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada
| | - Rohan John
- Department of Pathology, University Health Network, Toronto, Canada
| | - Akanchaya Rana
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada.,Institute of Medical Sciences
| | | | | | - Saidah Hack
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada
| | - Heather N Reich
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada.,Institute of Medical Sciences.,Department of Medicine, and
| | | | - Daniel C Cattran
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada.,Institute of Medical Sciences.,Department of Medicine, and
| | - Andrew D Paterson
- Institute of Medical Sciences.,Department of Medicine, and.,Genetics and Genome Biology, Research Institute at Hospital for Sick Children, Toronto, Canada; and.,Division of Epidemiology and Biostatistics, Dalla Lana School of Public Health, Toronto, Ontario, Canada
| | - York Pei
- Division of Nephrology and.,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada.,Institute of Medical Sciences.,Department of Medicine, and
| | - Moumita Barua
- Division of Nephrology and .,Toronto General Hospital Research Institute, Toronto General Hospital, Toronto, Canada.,Institute of Medical Sciences.,Department of Medicine, and
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